Automotive A-Z: Terminology Guide

Have you ever felt like you need a translator while reading about vehicles or discussing them with a mechanic? The automotive world can be full of technical jargon and industry-specific terms that could leave even car enthusiasts scratching their heads.

Whether you’re a first-time car owner, an aspiring mechanic, a car enthusiast, or even an experienced driver, understanding automotive terminology can be a daunting task. This industry, like many others, is full of specific terms and phrases that can sound like a foreign language to the uninitiated.

That’s why we’ve put together this automotive glossary. It’s designed to help you navigate through the complex language of the automotive world with ease. This glossary aims to break down the terminology barrier, allowing you to confidently converse about vehicles, understand auto repair processes, and make informed decisions about your own vehicle’s needs.

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Accelerator: Also known as the gas pedal, it regulates the amount of fuel delivered to the engine, controlling the vehicle’s speed.

Accessory Belt (or Drive Belt): This is either a V-shaped or flat serpentine belt that’s propelled by the crankshaft pulley, transferring this force to various components such as the alternator, air conditioning compressor, fan, power-steering pump, and water pump.

Adaptive Cruise Control: An enhanced form of cruise control that can be programmed to keep a safe distance from the vehicle ahead. It also provides precautionary measures if a collision appears imminent.

Additives: These are substances added to gasoline, diesel fuel, coolant, or engine oil. They perform various functions, such as cleaning gasoline and diesel fuel injectors, adding water pump lubricant and corrosion preventers to coolant, and enhancing the viscosity of engine oil.

Aftermarket: Refers to products or parts that are not installed on or provided with the vehicle at the time of purchase. These are typically items purchased post-purchase from sources other than the vehicle manufacturer.

Air Bag: An inflatable bladder designed to deploy from the dashboard, steering wheel, or side panels during a collision to safeguard the vehicle’s occupants.

Air Cleaner: Also known as the cold air collector box in modern vehicles, it is positioned on or in the air inlet duct to the fuel injection system or carburetor. It contains an air filter, which eliminates dust and dirt from the air before it enters the engine.

Air Filter: A crucial component in a vehicle’s intake system. Its primary purpose is to filter out dust, dirt, and other airborne debris from the air before it enters the engine. By doing so, the air filter ensures that the engine receives clean air, which is essential for the combustion process. Clean air helps in achieving optimal fuel efficiency, performance, and extends the lifespan of the engine. Typically made of pleated paper or foam, the air filter is housed in a plastic or metal container near the engine. Regular inspection and replacement of the air filter are vital to maintain the engine’s health and performance. While most air filters are disposable, certain aftermarket types can be cleaned and reused.

Air Inlet Duct (or Air Intake Hose): The passage through which air travels to the air cleaner and the intake manifold.

Air Springs: Computer-controlled rubber bladders filled with air that absorb the bumps and vibrations of driving. See also: Suspension System.

Air-Cooled Engine: An engine that utilizes air, instead of water, for its cooling system.

Alignment: Refers to the position of the car’s wheels relative to the car body. Correct wheel alignment enhances handling, performance, and reduces tire wear.

Allen Wrench: Also known as a hex wrench, it is an L-shaped rod designed to remove specific screws and fasteners with hexagonal holes.

Alloy Wheels: Decorative wheels typically made of aluminum or another metal alloy, usually featuring spokes radiating out from a central hub to the outer rim.

All-Wheel Drive: A drive system where power is delivered to all wheels, rather than just the front or rear, which can improve handling even on dry pavement.

Alternative Fuel: Any substance other than gasoline or diesel fuel used to power vehicles, such as electricity, compressed natural gas (CNG), liquid hydrogen, ethanol, or gaseous hydrogen for fuel cells.

Alternatively Fueled Vehicles: Vehicles designed to reduce air pollution, global warming, and dependence on fossil fuels by replacing or augmenting the traditional internal combustion engine (ICE). These include hybrids, clean diesels, vehicles powered by ethanol or hydrogen, natural gas vehicles (NGVs), and electric vehicles (EVs).

Alternator: This device creates an electrical current, which is stored in the vehicle’s battery and utilized to start the car and run its electrical equipment.

Anti-lock Braking System (ABS): This system has gained popularity due to its enhanced traction in slippery conditions and the ability to maintain vehicle control even during skidding.

Automatic Transmission: It selects the gear shifts automatically using a hydraulic converter and a set of bands and clutches or an electronic transmission controller.

Axle: This is the robust metal shaft where the vehicle’s wheels are attached.

Ball Joint: This movable joint in the vehicle’s steering linkage and suspension system allows rotation in any direction between the parts that it joins.

Ball Joints: Ball joints are a type of flexible joint that consist of a bearing stud and socket enclosed in a casing. They are pivotal in the suspension of your car and are used to connect the control arms to the steering knuckles. Ball joints provide a point of pivot between the wheels and the suspension, and allow free rotation in two axes simultaneously, enabling the front wheels to move up and down over bumps and turn left or right, regardless of the vertical movement. Like all car parts, ball joints can wear out over time and may need to be replaced.

Bands: Used in older automatic transmissions, bands are adjusted externally as part of regular transmission service without disassembling the transmission.

Battery: A car battery is an essential component of a vehicle’s electrical system. It is a rechargeable battery that supplies electrical energy to a motor vehicle. Its primary function is to power the starter motor, the lights, and the ignition system of a vehicle’s engine. A car battery is also known as an SLI (Starting-Lighting-Ignition) battery. It is designed to provide a quick burst of high energy to start the engine and is then recharged by the vehicle’s alternator.

Most car batteries are lead-acid batteries and are made up of plates of lead and separate plates of lead dioxide, which are submerged in an electrolyte solution of about 35% sulfuric acid and 65% water. This combination results in a chemical reaction that releases electrons, allowing them to flow through conductors to produce electricity.

As the battery discharges, it converts chemical energy into electrical energy, powering your car’s various systems. When you start the car, the alternator provides the battery with a fresh supply of electrons to replenish the ones lost during the discharge, effectively recharging the battery for the next use.

In addition to starting the car, the battery also stabilizes the voltage to keep the engine running. It is crucial for powering electronic devices in the car when the engine is not running as well. Regular maintenance and timely replacement of a car battery ensure that your vehicle is reliable and performs optimally.

Bearings: These are anti-friction devices usually found between two moving parts to reduce friction and ensure smooth operation.

Belt: In the context of an automobile, a belt is a loop of flexible material used to mechanically link two or more rotating shafts. It may be made of rubber, leather, or fabric. The most common types in cars are the serpentine belt, which drives multiple accessories, and the timing belt, which synchronizes the rotation of the crankshaft and camshaft(s).

Bike rack: A bike rack for cars is a device or attachment designed to securely hold one or more bicycles on a vehicle. This accessory enables safe and convenient transportation of bikes over long distances or during trips where riding the bike is not feasible. Different types include roof-mounted, hitch-mounted, and trunk-mounted racks, each with its own set of advantages and disadvantages for different vehicle types, usage scenarios, and personal preferences.

Biocide: This product eradicates any fungus or microbes that may contaminate diesel fuel.

Biodiesel: This is diesel fuel derived from agricultural and other waste products. It reduces dependence on crude oil and does not emit carcinogenic substances.

Bleed: This is the process of removing air bubbles from systems like brake, fuel injection, or cooling system.

Blend door: A movable flap or mechanism within a vehicle’s HVAC (Heating, Ventilation, and Air Conditioning) system that adjusts the mix of heated and cooled air sent into the cabin. By controlling the position of the blend door, the system can modulate the temperature of the air being blown into the vehicle’s interior, allowing occupants to achieve their desired comfort level. A malfunctioning blend door or its actuator can result in improper cabin temperatures or a lack of temperature control.

Block Heaters: These are devices that keep the engine warm when a vehicle is unused in extremely cold weather, crucial for starting diesel engines.

Blow-by: These are combustion products that leak past the piston rings during the piston’s power stroke, forming acid and sludge in the crankcase.

Blower Motor: An electric motor that powers a fan in a vehicle’s HVAC (Heating, Ventilation, and Air Conditioning) system. This fan circulates air through the system and into the vehicle’s cabin, either directly or after passing through components like the heater core or evaporator. The blower motor’s speed can typically be adjusted, allowing occupants to control the volume of air flow and, indirectly, the temperature and distribution of air within the vehicle’s interior. A malfunctioning blower motor can lead to reduced or absent airflow in the cabin.

Blue Books: These are listings of current prices for new and used cars based on their age, condition, and optional equipment.

Bolt: In the realm of automotive maintenance and tire changing, a bolt typically refers to the threaded fastener used to secure the wheel to the hub of the vehicle. These are commonly known as lug bolts or wheel bolts and are designed to withstand high levels of torque and stress. The bolts are tightened in place using a lug wrench or an impact wrench, and they are loosened for the removal of the tire. Proper torque must be applied to these bolts to ensure the wheel is safely attached, and they are often removed and re-tightened in a specific sequence to distribute force evenly across the wheel.

Boots: These are covers located at either end of a spark-plug cable to insulate the connections, or the protective cover of ball joints and constant velocity joints that holds the grease.

Bore: This is the width or diameter of the cylinder hole in an engine.

Brand Loyalty: The tendency of consumers to consistently choose and favor a particular automobile brand over others, often based on positive past experiences, emotional connection, perceived value, or brand reputation.

Brake Assist: This is a system that electronically amplifies braking power.

Brake Backing Plate: This is a metal plate, located inside the brake drum, on which various brake parts are mounted.

Brake Booster: This device is used in vehicles with power brakes, located between the brake pedal and the master cylinder, to amplify the force applied to the pistons in the master cylinder.

Brake Discs: Also known as rotors, these are utilized universally on front braking systems and on some rear braking systems.

Brake Drums: These are metal drums mounted at the rear wheels on some cars. The brake shoes press against the inner surfaces of the drums to slow or stop the car.

Brake Fluid: This is the liquid used in the hydraulic brake system to slow down or stop the car.

Brake Lines: This is a system of hoses and metal tubes through which the brake fluid flows from the master cylinder to the brakes at each wheel.

Brake Lining: This is a high-friction material attached to the brake pad or brake shoe. When pressed against the disc or the inside of the drum, it stops the wheel and the car.

Coolant (Antifreeze): This is a liquid that circulates through the engine block, radiator, and heating system to dissipate heat and keep the engine running cool. It prevents the engine from freezing in cold temperatures (hence the name “antifreeze”) and boiling over in high temperatures.

Cylinder Head: A cylinder head is a key component of an internal combustion engine. It sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This component is essential for controlling airflow in and out of the cylinders and housing components such as valves, spark plugs, and fuel injectors. In most engines, the cylinder head also includes passages for the engine’s coolant and oil to help maintain optimal operating temperatures.

Flushing the Cooling System (Backflushing): This is a maintenance procedure that involves removing old coolant from the vehicle’s cooling system and replacing it with new coolant to prevent buildup of rust and scale deposits, thereby keeping the engine cool and preventing overheating.

Brake Pads: These components consist of a friction material mounted on a metal backing plate. During braking, they are squeezed against a brake disc by brake caliper pistons to slow or stop the wheel. They are integral parts of the brake system and interact with the brake fluid.

Brake Shoes: These are curved metal pieces bonded with high-friction brake linings. They are pushed against the brake drums to decelerate or halt the vehicle.

Brake System: This system employs hydraulic pressure to ensure your vehicle can slow down and stop safely. It includes the master cylinder, brake lines, and either disc brakes or drum brakes at each wheel.

Bumper: A protective device attached to the front and rear ends of a vehicle. Its primary purpose is to absorb impact in minor collisions, thereby reducing damage to the vehicle’s frame and safety systems. Bumpers are typically constructed from materials such as steel, aluminum, rubber, or plastic that are designed to withstand force. They often house other safety and functional components like fog lights, parking sensors, and air intakes. While bumpers are an integral part of a vehicle’s safety features, they are also frequently styled to enhance the vehicle’s aesthetic appeal.

Bumpy ride: A vehicular experience where passengers feel frequent and often abrupt vertical motions, typically due to an uneven road surface, vehicle suspension limitations, or inflated tire conditions.

Bushing: This is a protective lining that provides a cushion between moving metal parts, reducing wear and vibration.

Cabin Air Filter: A component commonly found in modern vehicles designed to clean the air that enters the passenger compartment. The cabin air filter helps trap pollen, dust, and other airborne contaminants, ensuring a healthier and more pleasant environment for the vehicle’s occupants. It is typically located behind the vehicle’s dashboard or under the hood near the windshield. Regular replacement or cleaning of the cabin air filter is essential to maintain optimal air quality inside the car and ensure the efficient operation of the vehicle’s HVAC (Heating, Ventilation, and Air Conditioning) system.

Calipers: In disc brakes, these devices hold the brake pads. They use hydraulic pressure to press the pads against the brake disc to slow or halt the vehicle.

Cam: This is a metal disc with unevenly shaped lobes used in a camshaft to activate valve openings. In pre-1975 distributors, it forces the points to open.

Cam Lobes: These are the protrusions on a camshaft that interact with and activate cylinder head intake and exhaust valves, either directly or through devices like camshaft lifters or push rods.

Camber: This term refers to the inward or outward tilt at the top of a wheel, as seen from the front of the car. Proper camber is crucial for handling and minimizing tire wear.

Campervan: A campervan, also known as a recreational vehicle (RV), is a motorized vehicle outfitted with living quarters for camping and travel. These versatile vehicles merge transportation and recreational accommodation, providing amenities such as sleeping spaces, a kitchenette, and occasionally onboard bathroom facilities. Campervans vary from basic models, equipped with essential sleeping and cooking gear, to elaborate versions that include permanent fixtures, water supply, and electricity. They are favored by those who enjoy the leisure and adventure of travel without sacrificing the comforts of home.

Camshaft: A shaft with cam lobes that open and close the valves.

Camshaft Sensor: This device in electronic ignition systems lets the engine control unit (ECU) synchronize fuel injector operation with the spark plug firing sequence of the correct cylinder.

Car Dealership: A business establishment that specializes in the sale of new or used automobiles, typically representing one or multiple automobile manufacturers. Dealerships may also offer additional services such as vehicle maintenance, repair, parts sales, and financing options.

Car floor mat: protective covering specifically designed to fit on the floor of an automobile. Its primary purpose is to shield the car’s carpeting from dirt, mud, spills, and general wear and tear. Car floor mats can be made from various materials such as rubber, carpet, vinyl, or a combination of these. They can be generic or custom-designed to fit the specific make and model of a vehicle. Some floor mats also come with additional features like anti-slip backing or ridges to trap dirt and water. They are generally easy to install, remove, and clean, making them a practical accessory to maintain the cleanliness and longevity of a vehicle’s interior.

Car Wrap: A car wrap refers to a series of vinyl decals that are applied over the paint of a car, effectively covering the exterior surface. These wraps are used for various purposes, including advertising (commercial wraps), changing the vehicle’s appearance (color change wraps), or adding protective layers to the car’s surface. Car wraps can be applied to the entire vehicle or to specific sections, depending on the desired outcome. They are designed to be removable, allowing the car owner to revert to the vehicle’s original color or change its look again. The quality and durability of car wraps can vary, with high-quality wraps lasting several years if properly maintained.

Carburetor: An obsolete device that used to vaporize fuel and mix it with air in the correct proportions for the engine’s needs. Most vehicles built since 1990 use fuel-injection systems instead.

Caster: This is a wheel alignment adjustment that correctly positions the wheels so the tires naturally track in a straight line when moving forward. After a turn, the wheels tend to realign when the steering wheel is released.

Catalytic Converter: This is a pollution-control device that acts similar to an afterburner, consuming unburnt gas in the tailpipe and reducing nitrogen oxide emissions.

Cellulosic Ethanol: Also known as ethanol, this biofuel is produced from various forms of cellulose such as straw, wood, and plant stalks.

Cetane Rating: This is a measurement of diesel fuel quality, determined by the delay between fuel injection and ignition. It assesses how readily the fuel ignites and how quickly it burns.

Charging System: This system uses an accessory belt driven by the engine to enable the alternator (or generator) to generate electrical current. The current is stored in the battery and supplied to the electrically operated parts of the vehicle.

Chassis: The structural framework of a truck or SUV that remains after the body and fenders are removed.

Cherry Condition: A term used to describe a vehicle that has been maintained in or restored to perfect condition.

Circuit: In the context of automotive electronics, this refers to the path through which electrical current flows in an electrical system.

Classic Car: Typically refers to a vehicle model widely regarded as one of the finest of its time. Classic cars aren’t necessarily extremely old – for instance, Ford Mustangs and Volkswagen Beetles from the late 1960s have been considered classics for years.

Clean Diesel: This term refers to a diesel engine that has been engineered to produce fewer harmful emissions. It can also refer to types of diesel fuel that burn cleaner, like biodiesel or low-sulfur diesel.

Clear Coat: A finishing layer applied to modern vehicles that protects the paintwork and helps prevent rust.

Clip and retainer: Clips in the automotive context refer to various types of fastening devices used to hold components together within a vehicle. They are commonly used to secure panels, trims, liners, and other parts in both the interior and exterior of a vehicle. These clips are designed for quick and easy assembly and disassembly, allowing for maintenance or replacement without causing damage to the components they hold together. Automotive clips come in various shapes and sizes, including push-in clips, screw clips, and snap clips, each designed for specific applications and strength requirements. Retainers are mechanical components used to securely hold a part in place on a car or truck. They are often used in conjunction with fasteners such as bolts, screws, or clips to prevent movement or loosening. Retainers can be found in multiple applications within a vehicle, such as holding brake pads in place, securing electrical connectors, or maintaining the position of underbody shielding. They are typically made of metal or plastic and are chosen based on the demands of the environment in which they will operate, such as temperature extremes, vibration, and exposure to automotive fluids.

Clock spring: A clock spring, in automotive context, is a special type of electrical connector that allows a vehicle’s steering wheel to turn while maintaining a continuous electrical connection to components housed within the steering wheel. These components often include the airbag, horn, and various control buttons for vehicle systems.

Cloud Point: This term refers to the lowest temperature at which diesel fuel starts to solidify and become cloudy.

Clutch: In vehicles with manual transmissions, this device disengages the engine from the transmission to allow gear changes, and then reconnects them to operate at a new speed.

Clutch Disk: In a manual transmission, this is a spinning plate at the end of the driveshaft, facing the engine flywheel, and covered with a friction surface. When the clutch is engaged, the clutch disk is forced against the flywheel, synchronizing the engine and transmission speeds.

Clutch Pedal: In vehicles with manual transmissions, this pedal is situated on the floor to the left of the brake pedal. Pressing it disengages the clutch, allowing the engine and the transmission to rotate independently and enabling gear changes.

Coil: This term refers to the ignition coil, a key component in the ignition system of a vehicle.

Coil Springs: These are large metal coils that support the weight of the vehicle and absorb shocks and bumps as the vehicle is driven. They’re often found near the front wheels, but many vehicles also have them at the rear. Shock absorbers frequently run through the center of the coil springs.

Cold Air Collector Box: A box that houses the air filter, performing the same function as an air cleaner.

Combustion: The intense burning of the fuel-air mixture in the combustion chamber of an engine.

Combustion Chamber: The section of the engine cylinder where the fuel-air mixture is compressed by the piston and ignited by a spark from the spark plug.

Common Rail Fuel Injection: This is a fuel system found in diesel engines where diesel fuel is pumped at high pressure into a distributor tube (the “rail”), which then delivers fuel to all the fuel injectors.

Compressed Natural Gas (CNG): An alternative fuel source that’s designed to replace gasoline for powering vehicles. It’s used in Natural Gas Vehicles (NGVs).

Compression Gauge: A device used to measure the pressure generated in an engine cylinder when the piston is at its highest point and the fuel/air mixture is compressed into the smallest possible space. A low reading can indicate the need for engine repairs.

Compression Ratio: This is the ratio of the volume of an engine cylinder and its combustion chamber when the piston is at its lowest point to its highest point. It is a measure of how much the fuel/air mixture is compressed.

Connecting Rod: The metal rod that connects the piston to the crankshaft, converting the piston’s up-and-down motion into the crankshaft’s rotational motion. “Throwing a rod” refers to a situation where a broken connecting rod pierces the engine block.

Constant Velocity Joints (CV Joints): These are ball-and-socket joints that transmit engine power from the transaxle to the wheels. They allow for engine torque transmission while accommodating full steering and suspension movement.

Continuously Variable Transmission (CVT): This is a type of automatic transmission that doesn’t have a set number of gears. Instead, it can continuously vary the gear ratio for optimal performance and fuel economy.

Control Arms: These are upper or lower suspension components, shaped like the letter A, that are mounted on the frame and support the ball joints and steering knuckles.

Coolant: Also known as antifreeze, this is a solution (usually ethylene glycol or propylene glycol) that raises the boiling point and lowers the freezing point of water in the vehicle’s cooling system. It also helps prevent rust, corrosion, and lubricates the water pump.

Coolant Recovery System: This is a reservoir that collects coolant expelled from the cooling system and then returns it when it cools down. It requires a special radiator pressure cap. When part of the original equipment, the system is sometimes referred to as a closed cooling system.

Cooling System: This is the system that stores, circulates, and cools a mixture of water and coolant. The coolant flows through the engine block and cylinder heads, and then through the radiator, to prevent the engine from overheating.

Core Charge: “Core” stands for “Cash On Return”. It refers to a deposit you pay when you purchase a part and it is refunded when you return the old part. This is common for parts like alternators or starters.

Core Plugs: Metal plugs on the sides of the engine block designed to prevent damage by popping out under excessive pressure, such as from ice formation. Also called freeze plugs.

Corrosion: In the automotive context, corrosion refers to the process by which metal parts of a vehicle deteriorate as a result of chemical reactions between the metal and substances in the environment, such as water, salt, or pollutants. This is a naturally occurring process that can lead to serious problems if not addressed promptly.

Corrosion typically appears as rust (in the case of iron and steel), a flaky, reddish-brown substance. However, other metals commonly used in vehicles, such as aluminum and copper, can also corrode, albeit with different visual indications. There are several key areas where corrosion often occurs in vehicles:

• Body Panels and Frame: The car’s body panels and frame are the most susceptible to rust, particularly in regions that use road salt in winter. Over time, rust can weaken these structures, potentially leading to structural failures.
• Exhaust System: The exhaust system is exposed to both high temperatures and a corrosive environment, making it a common place for rust to form.
• Brake Lines and Fuel Lines: These are critical systems where corrosion can lead to serious safety issues if leaks develop.
• Electrical Connections: Corrosion can also impact the vehicle’s electrical systems, leading to poor connections and malfunctioning components.

To protect against corrosion, vehicles are typically treated with rust-proofing and regular washing can also help remove corrosive substances. Regular inspections and maintenance can help identify and address corrosion before it leads to serious issues.

Cotter Pin: A pin that is split in the middle and used as a locking device. It is typically inserted into a hole drilled through a nut and bolt to prevent the nut from unscrewing.

Crankcase: The lower portion of the engine where the crankshaft is housed. The oil pan is located at the bottom of the crankcase.

Cranking: The act of engaging the starter by turning the key in the ignition switch, causing the engine to turn over.

Crankshaft: The primary rotating shaft inside an engine. It transforms the linear motion of the pistons into rotational motion that is transferred to the wheels of the vehicle.

Crankshaft Position Sensor: A device that provides information to the powertrain control module about the position of the crankshaft. This information allows for proper timing of ignition and fuel injection.

Crankshaft Pulley: A grooved wheel attached to the front end of the crankshaft. It’s linked by accessory belts to various devices like the alternator, water pump, etc. Also called a harmonic balance wheel.

Creeper: A low, wheeled platform that a mechanic lies on to move around easily while working under a vehicle.

Cross-Shaft Lug Wrench: Another name for a lug wrench, a type of wrench used to remove lug nuts from the wheels of vehicles.

Cruise Control: A feature in vehicles that maintains a preset speed until overridden by the driver, usually by stepping on the brake pedal.

Cylinder: A hollow tube-shaped component in the engine block where the piston moves up and down, compressing the fuel/air mixture that powers the engine.

Cylinder Block: Also known as the engine block, this is the main part of the engine where the cylinders are located.

Cylinder Head: The part of the engine that sits above the engine block and houses the combustion chambers and the valves. Spark plugs are usually inserted into the cylinder head.

Cylinder Sequence: The arrangement of cylinders in an engine. This order is crucial for locating the first cylinder when adjusting timing with a timing light.

Detailing: The comprehensive cleaning and restoration process of both the interior and exterior of a vehicle to produce a show-quality level of detail. It goes beyond the standard cleaning procedures to ensure deep cleaning, rejuvenation, and protection of various parts of a vehicle.

Diesel Engine: An engine that burns diesel fuel instead of gasoline. The fuel is directly injected into the combustion chamber and ignited by the heat caused by intense compression, not by a spark from a spark plug.

Diesel Fuel: Fuel used in diesel engines. It is similar to home heating oil, kerosene, and jet fuel.

Dieseling: A term used to describe when an engine on older, carbureted vehicles continues to run after the ignition switch has been turned off.

Differential: A gearbox, usually located between the rear wheels in rear-wheel-drive vehicles, that turns the rotational motion of the driveshaft 90 degrees to drive the rear axles and wheels. It also allows each wheel to turn at different speeds while cornering.

Dipstick: A metal rod inserted into a reservoir to check the fluid level. Common dipsticks check engine oil, transmission fluid, and power steering fluid levels.

Disc Brakes: Brakes that have calipers with high-friction brake pads, which squeeze a brake disc (or rotor) attached to the wheel to stop the car.

Displacement: The total volume of all the cylinders in an engine. It indicates the amount of fuel and air the cylinders can hold before compression occurs.

Distributor: Part of the ignition system that sends the appropriate amount of electrical voltage to each spark plug in the correct sequence. In distributorless ignition systems, this task is performed electronically.

Distributor Cap: A protective cap that covers the distributor. It has outlets for each spark plug wire and an additional outlet for the wire from the ignition coil. The cap prevents dirt and moisture from getting into the distributor.

Downshifting: The act of manually shifting to a lower gear to accelerate, climb a steep hill, or use the engine to slow down on a decline.

Drag Racing: A type of motor racing in which two competitors race their vehicles from a standing start over a straight, measured distance, typically a quarter-mile or an eighth-mile. The primary objective is to complete the distance in the shortest possible time. Drag racing involves high-powered vehicles, often specially modified, accelerating rapidly in a straight line. The race usually takes place on a drag strip, a specialized track for this type of racing. Reaction times, engine power, and traction are critical factors in determining the winner.

Drivetrain: The components that transmit power from the engine to the drive wheels. This includes the clutch, transmission, driveshaft, differential, and axles. In front-wheel-drive vehicles, the transmission and differential are combined into one unit called a transaxle, which connects directly to the drive wheels.

Engine: In the automotive context, an engine, also known as an internal combustion engine, is a machine designed to convert one form of energy into mechanical energy. It serves as the heart of a vehicle, creating the power necessary to move the car by burning fuel (typically gasoline or diesel) in a controlled manner.

Car engines operate using a four-stroke combustion cycle: intake, compression, combustion (power), and exhaust. Here’s a brief description of each phase:

• Intake: The intake valve opens to let in a mixture of air and fuel into the cylinder while the piston moves downwards.
• Compression: The intake valve closes and the piston moves upwards, compressing the air-fuel mixture.
• Combustion (Power): The spark plug ignites the compressed air-fuel mixture, creating a small explosion that pushes the piston down. This generates the power to turn the car’s wheels.
• Exhaust: The exhaust valve opens to let out the combustion gases (exhaust), and the piston moves upwards to push the gases out of the cylinder.

This cycle repeats many times per minute, with each repetition contributing to the engine’s power output. The efficiency, power output, and performance characteristics of a car’s engine greatly affect the vehicle’s overall performance, fuel economy, and reliability. Different vehicles utilize different types of engines, including inline, V-type, boxer, and more recently, electric motors in electric vehicles.

Engine Block: The engine block, also known as a cylinder block, is the core structure of an internal combustion engine. It is a robust, cast structure that houses the cylinders and other components of an engine, such as the crankshaft. The engine block contains the cylinders where the pistons move up and down, and it often includes pathways for coolant and oil to circulate, aiding in temperature regulation. The engine block forms the lower portion of the engine and provides the foundation to which other critical engine components are attached, including the cylinder head.

Exhaust System: An assembly of components in an internal combustion engine vehicle that guides waste exhaust gases away from the engine, treats these gases to reduce harmful emissions, and muffles engine noise. Its primary components include the exhaust manifold, oxygen sensors, catalytic converter, resonator, muffler, and tailpipe. The exhaust system is critical for safe operation, environmental compliance, and efficient performance of the vehicle.

Exhaust Manifold: A component of the exhaust system in an internal combustion engine that collects exhaust gases from multiple engine cylinders and funnels them into one pipe, leading towards the catalytic converter and ultimately out the tailpipe. The exhaust manifold is typically made of cast iron or stainless steel to withstand high temperatures and corrosive gases, and is designed to promote smooth and efficient exit of exhaust gases to optimize engine performance.

Extreme temperature: Temperature conditions beyond a vehicle’s standard operating ranges, potentially affecting performance, safety, and comfort.

High Extreme Temperature: Typically above 104°F (40°C). Can lead to:

• Engine overheating.
• Fluid degradation.
• AC system inefficiency.

Low Extreme Temperature: Typically below 14°F (-10°C). Results in:

• Reduced battery efficiency.
• Fluid thickening.
• Difficulty in engine start.

Fan: This is usually electrically driven and mounted in front of the radiator, or in older vehicles, driven by an accessory belt and located between the radiator and the engine. The fan draws air through the radiator to cool the liquid in the cooling system when the car is stationary or operating at low speeds.

Fan Belt: On older vehicles, this is a single flexible rubber belt that connects the fan, the water pump, and the alternator. The operation of the engine turns the fan, which turns the belt, driving the alternator and enabling it to generate electric current.

Feeler Gauge: A device for measuring the distance or gap between two surfaces. A wire or taper feeler gauge is used to gap spark plugs.

Fender: A component of a vehicle located over the wheel well. Its primary function is to prevent sand, mud, rocks, liquids, and other road spray from being thrown into the air by the rotating tire. Fenders are rigid and can be made from metal, plastic, or composite materials. They are shaped to fit snugly around the wheel well and can be attached to the vehicle through various methods, including bolts, clips, adhesives, or welding. In the event of a collision or damage, fenders serve to protect the wheel well and other vehicle components from further impact.

Firewall: The insulated partition that runs from the windshield down between the interior of the vehicle and the engine compartment. It protects the driver and passengers from engine fires, noise, and fumes.

Firing Order: The sequence in which the cylinders fire on a particular engine to distribute the shock of combustion evenly and reduce engine vibrations.

Flash Point: The temperature at which diesel fuel ignites.

Flat Rate Manual: A listing of almost every repair and maintenance job that can be done on a particular vehicle, along with the average time required for a technician to complete it. It is used by service facilities to estimate labor charges.

Flex-Fuel Vehicles: Vehicles that can operate on more than one type of fuel. Also known as dual-fuel or multi-fuel vehicles.

Fluid Levels: Fluid levels refer to the quantities of various liquids that are crucial for the efficient and safe operation of a vehicle’s systems. These fluids are typically housed in clear, marked reservoirs or can be checked using dipsticks or gauges. Maintaining appropriate fluid levels is essential for vehicle longevity and reliability. Various fluids play critical roles, such as engine oil which lubricates to prevent wear, coolant that regulates engine temperature, transmission fluid for smooth gear shifts, brake fluid to ensure effective stopping, power steering fluid for easier steering, windshield washer fluid for clear visibility, and differential fluid for gear lubrication. Maintaining these fluid levels is vital to prevent mechanical failures due to overheating or corrosion. Checking these fluids involves visual inspections of reservoir indicators, dipsticks, or dashboard gauges. Regular monitoring and timely servicing, as recommended by the manufacturer, are essential to avoid leaks and depletion. While handling these fluids, particularly used engine oil and brake fluid, care must be taken due to their hazardous nature, and proper disposal is crucial to protect the environment.

Flushing the Cooling System: The process of circulating water through the cooling system to remove old fluid and clean the system of rust and dirt.

Fossil Fuels: Fuels derived from petroleum, such as gasoline and diesel fuel. Because of their contribution to global warming and their dwindling supply, vehicles running on fossil fuels are increasingly being replaced by alternatively fueled vehicles.

Four-Stroke Power Cycle: Refers to the four movements of the piston – down and up, down and up – that draw the fuel/air mixture into the combustion chamber (intake stroke), compress the mixture (compression stroke), transmit the power created by the combustion to the crankshaft (power stroke), and expel the exhaust gases from the cylinder (exhaust stroke).

Four-Wheel Drive: This allows a driver to adjust a vehicle to operate in difficult terrain; how this is accomplished differs from one model to another. Four-wheel drive should only be used when needed because it doesn’t work efficiently under normal road conditions.

Friction: This refers to the resistance that one surface or object encounters when moving over another. In cars, friction creates heat and wears down moving parts. Lubrication systems use oil to reduce this friction and prolong the life of your vehicle.

Front-End Alignment: See alignment. This refers to the adjustment of a vehicle’s front-end suspension parts to ensure that the tires are properly aligned. Proper alignment affects the lifespan of the tires and the vehicle’s handling and fuel efficiency.

Front-Wheel Drive: A system in which the vehicle is propelled by its front wheels, eliminating the need for a long driveshaft and a center floor hump found in cars with rear-wheel drive.

Fuel/Air Mixture: This is a vaporized, mist-like combination of fuel and air that’s compressed in the cylinders and ignited to produce the power that drives the engine and the vehicle.

Fuel Cell: A device that generates electrical power through a chemical reaction by converting a fuel (typically hydrogen) into electricity.

Fuel Filter: A device that removes impurities from the fuel before it enters the engine. It can be found either in the fuel line under the car or mounted on the firewall.

Fuel Gauge: An instrument on a vehicle’s dashboard that indicates the amount of fuel in the fuel tank.

Fuel Injection: A fuel system that delivers a specific amount of fuel to each combustion chamber in response to changes in engine speed and driving conditions. It replaces the carburetor in modern vehicles.

Fuel Injection Pump: Mostly found on diesel engines, it sends fuel under high pressure to the fuel injector nozzles.

Fuel Injector: A device that sprays fuel into each combustion chamber of an engine. The amount of fuel sprayed is controlled by the engine control unit (ECU).

Fuel Lines: The hoses or pipes that carry fuel from the fuel tank to the engine.

Fuel Pressure Regulator: A device that maintains the correct pressure in the fuel system and sends unused fuel back to the fuel tank.

Fuel Pump: A device that moves fuel from the fuel tank and sends it through the fuel lines to the fuel injectors.

Fuel Rail Assembly: A pipe in a fuel injection system that supplies fuel to the set of fuel injectors connected to it.

Fuel Supply Pump: See fuel transfer pump. This refers to the pump that transfers fuel from the fuel tank to the engine.

Fuel System: A system that stores, cleans, and delivers fuel to the engine in appropriate quantities to meet the varying needs as you drive. It includes components such as the fuel tank, fuel lines, fuel pump, fuel filter, and fuel injectors (or the carburetor on older vehicles without fuel injection).

Fuel Tank: The storage compartment, usually located under the trunk in most cars, that holds the vehicle’s fuel.

Fuel Transfer Pump: A mini-pump on diesel engines, each responsible for delivering fuel from the fuel injection pump to one of the fuel injector nozzles at a high pressure, usually over 1,000 psi (pounds per square inch). It’s also found on gasoline engines.

Fuses: Devices that protect the electrical components and wiring in your vehicle, located in a fuse box or boxes often found under or near the dashboard or under the hood.

Gap: The space between the spark plug electrodes. Adjusting this space is referred to as “gapping.”

Gapper: See feeler gauge. A tool used for measuring and adjusting the gap in a spark plug.

Gas Gauge: See fuel gauge.

Gas Tank: See fuel tank.

Gasket: A seal, often made from rubber, cork, paper, or metal, that is placed between two parts to prevent the leakage of gases, fluids, or compression.

Gasohol: See ethanol. A blend of gasoline and ethanol, typically containing 90% gasoline and 10% ethanol.

Gauge: In the automotive context, a gauge is an instrument used to measure and display various operational parameters of a vehicle. These parameters can include speed, fuel level, engine RPM (revolutions per minute), oil pressure, coolant temperature, and battery voltage, among others. Gauges are integral to a vehicle’s dashboard and provide the driver with crucial information necessary for safe and efficient vehicle operation. There are several types of automotive gauges, including analog gauges, which display information using a needle or dial, and digital gauges, which show data in numerical or graphical formats on an LCD or other types of displays. Some modern vehicles incorporate a combination of both analog and digital gauges or use fully digital instrument clusters that can be customized to display a variety of information according to the driver’s preferences.

Gear Ratio: The ratio of the rotational speeds of the first and second gears. It determines the speed of the engine compared to the output speed of the transmission and/or the differential in a given gear.

Gear oil: Specialized lubricant designed for use in vehicle transmissions, differentials, and transfer cases. It protects gears from wear, handles high-pressure conditions, and maintains performance across a range of temperatures.

Gear Selector: A gearshift for vehicles with automatic transmissions. Its location can vary: it might be on the side of the steering column, in a console, on the dashboard, or on the floor between the front seats.

Gears: Devices in the transmission that allow the vehicle to move forward and backward at various speeds.

Gearshift: A lever in vehicles with manual transmissions that the driver uses to select and change transmission gears.

Generator: See alternator. An electrical device for converting mechanical energy into electrical energy.

Glow Plug: An electrical component located in the combustion chamber of a diesel engine that helps heat up the air in the chamber, allowing the diesel fuel to ignite more quickly.

Governor: On diesel engines, this device controls the exact amount of fuel sent to the fuel injector nozzles and ensures the engine doesn’t run so fast that it causes damage due to excessive heat and pressure.

GPS Tracker: A GPS tracker in the automotive context is a device that uses the Global Positioning System to determine and track the precise location of a vehicle. This information is typically collected and transmitted to a central database or accessible via software over the internet, allowing real-time or historical navigation of the vehicle. GPS trackers are widely used for a variety of purposes, including theft prevention, fleet management, parental control over a teen driver’s car, and personal vehicle tracking for efficiency and safety.

Grease: In the automotive world, grease refers to a semi-solid lubricant used to reduce the friction between moving mechanical parts. It consists of an oil base combined with a thickener to give it its characteristic consistency. Grease is commonly used in areas like wheel bearings, suspensions, and universal joints to protect them from wear and tear, reduce heat buildup, and prevent rust and corrosion. It’s also resistant to being squeezed out or washed away, which makes it a good choice for parts exposed to harsh conditions or heavy loads.

Grease Fitting: A device that retains grease to cushion two moving parts, allowing them to move freely and preventing them from wearing each other out. It is commonly found in components such as ball joints, steering knuckles, and tie rods.

Grease Seal: A circular, metal-backed, rubber device that prevents grease from leaking out and protects parts like wheel bearings from dust and water.

Ground: In an electrical context, ground refers to a conductive body, often the earth, used as a common return path for electric current in a circuit.

Guarantee: A promise by the manufacturer to fix or replace a specific part if it fails within a specific time period or distance. Similar to a warranty.

Handbrake: A handbrake, also known as a parking brake, emergency brake, or e-brake, is a device in a vehicle used to keep it stationary. It functions independently of the main hydraulic brake system and is typically engaged by a mechanical lever or an electronic switch. While most commonly located between the front seats, the handbrake can also be found under the dashboard or to the right of the driver in some vehicle designs. Its primary purpose is to prevent the vehicle from rolling when parked and to provide an auxiliary means of stopping the vehicle in case of main brake system failure.

Harmonic Balance Wheel: See crankshaft pulley. It helps reduce engine vibration and serves as a pulley for drive belts.

Head Gasket: The seal between the cylinder head and the engine block. This gasket prevents coolant from entering the cylinders and prevents contamination by exhaust gases. A “blown” head gasket can cause a serious loss of compression.

Headlight: A headlight is a critical component of automotive vehicles, consisting of an electric lamp with a reflective surface and often a lens, housed within an assembly. It is mounted on the front end of a vehicle with the primary purpose of illuminating the road ahead during low-light conditions, such as at night or in adverse weather. Headlights enable the driver to see the roadway and help the vehicle to be seen by others, thereby playing a vital role in road safety. Automotive headlights come in various technologies, including halogen, LED (Light-Emitting Diode), HID (High-Intensity Discharge), and laser, each differing in brightness, color temperature, energy efficiency, and lifespan.

Headliner: The fabric or vinyl material that covers the interior roof of a vehicle.

Heater Core: A component of the car’s heating system that heats the passenger compartment. Hot coolant from the engine circulates through it, heating the air that is then blown by an interior fan into the vehicle.

Heating System: The heating system refers to the assembly of components that collectively generate, circulate, and regulate warm air inside the vehicle cabin. This system is usually integrated with the vehicle’s cooling system and often shares components such as the radiator, coolant, and blower motor.

Hex Wrench: Also known as an Allen wrench. A tool used to drive bolts and screws with hexagonal sockets.

High Intensity Discharge Lamps (HID): Headlamps filled with halogen or xenon gas that are brighter and use less power than traditional sealed beam units.

Horn: A device in a vehicle that emits a loud warning sound, typically activated by the driver pressing a button on the steering wheel or when the vehicle is locked using a remote control. Used primarily to alert other drivers or pedestrians of the vehicle’s approach or presence, or to signal potential hazards.

Horsepower: A unit of power that equates to the energy required to lift 550 pounds one foot in one second, or 33,000 foot-pounds per minute.

Hose: A hose is a flexible tube designed to carry fluids from one location to another in a vehicle. Hoses in automobiles are often made of reinforced rubber to hold up under the high pressure and temperature conditions they encounter. They are used for various purposes, including the transportation of coolant, fuel, or brake fluid.

Hose Clamps: Adjustable metal rings placed around a hose where it connects to another part to prevent leaks and keep the hose in place.

Hubcap: See wheel cover and alloy wheels. A decorative disk that covers the hub of a car’s wheel.

Humidity Levels: The concentration of water vapor present in the air within or surrounding a vehicle. In the automotive world, humidity levels can influence various aspects of vehicle performance, comfort, and durability. High humidity can lead to issues such as fogging of windows, corrosion of certain parts, and compromised effectiveness of cooling systems. Low humidity, on the other hand, might cause static electricity build-up and reduced effectiveness of certain cabin comfort features.

Hybrid: An alternatively fueled vehicle that combines a small internal combustion engine and an electric motor to maximize power output with minimum emissions and fuel consumption.

Hydraulic: Refers to systems that use fluid under pressure to transmit force or power. In vehicles, hydraulic devices can include automatic transmissions, power steering systems, and brake systems.

Hydraulic Electronic Control Unit (HECU) Fuse: A safety device in the form of a strip or wire made of a fusible material that protects the Hydraulic Electronic Control Unit (HECU) in a vehicle. The HECU manages and controls the electronic components of a vehicle’s hydraulic brake system. The fuse is designed to melt and break the circuit in case of excessive current, preventing potential damage or malfunction of the HECU.

Hydrogen Vehicle: A hydrogen vehicle is a type of transportation mechanism that uses hydrogen as its primary source of power for locomotion. Unlike conventional vehicles which run on gasoline or diesel, hydrogen vehicles are powered by fuel cells that convert hydrogen gas into electricity. These vehicles produce zero emissions at the point of use, with water vapor being the only byproduct, thus making them an environmentally friendly alternative to fossil fuel-powered vehicles.

Hydrometer: A device used to determine the specific gravity of a liquid. It’s used to test battery electrolyte and the percentage of coolant in the cooling system.

Idiot Lights: A colloquial term for the dashboard indicators that light up when your car is already in trouble from lack of oil, overheating, etc. These are different from gauges, which indicate levels of oil and engine temperatures, enabling the driver to prevent breakdowns and damage.

Idle Control Valve: Also known as the idle air control valve, this component regulates the amount of air that bypasses the throttle plate in fuel-injected engines when the throttle is closed (i.e., when the vehicle is idling). The idle control valve helps maintain the correct idle speed, preventing the engine from stalling when the vehicle is stopped and the throttle is not engaged.

Idling: This refers to the state of an engine running while the vehicle is not in motion.

Ignition Coil: Part of the ignition system that receives a small amount of electrical voltage from the battery, amplifies it, and sends it to the spark plugs via the distributor. In distributorless ignition systems, each spark plug may have its own coil.

Ignition Control Module (ICM): A computer in an electronic system that receives data from sensors and controls the firing of the spark plugs. In some systems, it’s controlled by the engine control unit (ECU).

Ignition Switch: The mechanism by which you activate a vehicle’s electrical circuits and start the engine. It is often a slot for the vehicle’s key. In newer vehicles, this could be a push button.

Ignition System: A system that provides the high-voltage electric current used to ignite the fuel/air mixture in the cylinders.

Ignition Timing: The timing of the spark plug’s spark in the combustion chamber during the piston’s compression stroke. This timing is preset by the manufacturer and rarely needs to be adjusted in vehicles with electronic ignition systems.

Injector Driver: A transistor controlled by the ECU that determines how much fuel to spray into each cylinder to mix with the air for the optimum explosion to drive the piston.

Injector Pulse Width: The duration that the engine control unit (ECU) maintains the electrical circuit to a fuel injector. Based on sensor data, the ECU adjusts the pulse width, thereby controlling the fuel/air mixture.

Inlet Valve: See Intake valve. A valve that allows air-fuel mixture into the cylinder of an internal combustion engine.

In-line Engine: An engine in which the cylinders are set in a single row with the crankshaft running along the bottom. Also known as a straight engine.

Intake Manifold: This chamber, located near the top of the engine, routes the air needed for combustion to the cylinders.

Intake Port: The opening in the cylinder head that contains the intake valve. The air and fuel pass through this port into the combustion chamber.

Intake Valve: A valve that opens to allow the fuel/air mixture to enter the combustion chamber. Also known as the inlet valve.

Integral Equipment: Any device or system that’s designed for, and installed in, a vehicle by the manufacturer rather than added to a finished vehicle at a later date.

Internal Combustion Engine (ICE): An engine that operates on power released by vaporized fuel and air burning inside the engine itself, rather than on an outside source of combustion like a steam engine.

Jack: A device for lifting all or part of a vehicle off the ground to make repairs easier. Types of jacks include tripod, scissors, and hydraulic jacks.

Jack Stand: A safety device that prevents the vehicle from falling to the ground if the jack is removed or faulty.

Jerking: In the automotive context, “jerking” refers to a sudden, rough, or uneven movement of a vehicle, particularly while accelerating or driving at a steady speed. This phenomenon is typically characterized by abrupt and involuntary jolts or surges in the car’s motion. Jerking can be caused by various issues related to the engine, fuel system, transmission, or other mechanical components.

Journal: The area on the crankshaft that fits into the bearings in the engine block and the lower portion of the connecting rod(s). It’s cushioned by a layer of oil and metal bearings to prevent premature wear.

Jumper Cables: Cables used to jump-start a car by conducting current from one battery to another, allowing a vehicle with a drained battery to start and begin to generate its own power.

Keyless Entry: A feature that allows you to open a vehicle’s door without a key. The vehicle recognizes a chip in a remote device.

Keyless Ignition: A feature that allows you to start and run a vehicle without the need to insert a key in the ignition switch. This feature is often combined with keyless entry.

Knocking: A sound that occurs in the cylinders when the fuel/air mixture is ignited too soon. The subsequent explosion hits the piston as it travels up the cylinder on the compression stroke. It’s usually due to faulty timing, low-octane gas, or a build-up of carbon in the cylinders.

Leaf Springs: A series of flexible steel plates stacked one on top of the other that carry the weight of the vehicle and bend to absorb the bumps and shocks of driving. They’re most often used in the rear suspensions of trucks and some sport-utility vehicles.

Lock: A mechanical or electronic device integrated into a vehicle to secure it against unauthorized access, theft, or operation. Locks in the automotive world are commonly used for doors, ignition systems, trunks, and glove compartments.

Examples include:

• Door Lock: A device that secures the vehicle’s doors from opening without the correct key or electronic signal.
• Ignition Lock: A mechanism that prevents the vehicle’s engine from starting without the correct key or electronic authorization.
• Steering Wheel Lock: A device that locks the steering wheel in place, preventing it from turning and thus deterring theft.
• Central Locking System: A system that allows all of a vehicle’s doors (and often the trunk) to be locked or unlocked simultaneously, often remotely.

Related mechanisms: Many modern vehicles utilize keyless entry systems, where a remote transmitter or smart key communicates with the car to lock or unlock doors and even start the ignition.

Lubrication: In the automotive world, lubrication refers to the process of reducing friction and wear between moving parts within a vehicle by applying a substance known as a lubricant. The most common lubricant used in vehicles is motor oil, but others, such as grease and synthetic lubricants, are also used in different components of a vehicle. Lubrication serves a number of crucial functions in an automobile:

• Reducing Friction and Wear: Lubrication forms a protective film between moving parts, reducing direct contact and, therefore, friction and wear. This prolongs the lifespan of the vehicle’s components.
• Dissipating Heat: Moving parts generate heat due to friction. Lubricants absorb this heat and carry it away, helping to prevent overheating.
• Preventing Corrosion: Many lubricants have anti-corrosive additives that protect metal parts from rust and corrosion.
• Cleaning: Lubricants, particularly engine oil, help to keep the engine clean by suspending dirt and contaminants, which are then removed when the oil is changed.

In short, proper lubrication is critical for the smooth operation and longevity of a vehicle. Regular maintenance, including oil changes and checking and replenishing other lubricants, is a crucial part of vehicle care.

Lubrication System: This system manages the storage, cleaning, cooling, and recirculation of oil through the engine to provide lubrication and cooling for the moving parts. Key components include the oil pan, oil pump, oil filter, and the oil gauge or warning light located on the dashboard. The oil level in the system can be checked using the oil dipstick.

Lug Nuts: These are the nuts responsible for securing the wheel onto a vehicle. They are removed with a lug wrench when changing a tire. Some vehicles use lug bolts instead of lug nuts.

Lug Wrench: A wrench specifically designed for tire changes, used to remove the lug nuts that attach the wheel to the vehicle. The cross-shaft type provides optimal leverage. It’s recommended to keep one in the vehicle’s trunk.

Mass Air Flow Sensor (MAF): A Mass Air Flow Sensor (MAF) is a critical component in the fuel injection system of a modern internal combustion engine. It measures the volume and density of air entering the engine, providing this data to the Engine Control Unit (ECU). The ECU uses this information to determine the optimal amount of fuel to inject into the engine cylinders, ensuring efficient combustion and engine performance.

Malfunction Indicator Lights (MIL): These are dashboard alerts triggered by various electronic control modules that monitor numerous automotive systems. They notify drivers about issues that may require attention, possible adjustment, or repair. They are also known as warning lights, “Check Engine” lights, or malfunction indicator lamps.

Manual Transmission: A type of transmission where the driver manually selects gears using a hand-operated gearshift and a foot-operated clutch. Also referred to as a standard transmission. Contrast this with an automatic transmission and gear selector.

Master Cylinder: A device that stores brake fluid and forces it hydraulically through the brake lines to the brakes when the brake pedal is pressed. Hydraulic clutches also use master cylinders.

Mechanic’s Lien: A legal remedy available in some jurisdictions that allows repair facilities to seize and sell a vehicle to recover costs if a repair bill is not paid.

Misfiring: This refers to the failure of the fuel/air mixture in one or more cylinders to combust while the vehicle is running. It can be due to poor compression caused by worn or improperly adjusted valves, worn piston rings, a faulty head gasket, or poor ignition due to worn, dirty, or improperly gapped spark plugs, poor fuel delivery, or faulty ignition wiring.

Models: 1. Specific versions of vehicles that are designed and produced by automobile manufacturers, each with a unique set of features, designs, and options. Models are characterized by their brand (e.g., Ford, Toyota), nameplate (e.g., Mustang, Camry), and often a series of trim levels offering varying levels of equipment or packages. 2. Refers to a particular year’s version of a vehicle that may have updates or changes from the previous year, including but not limited to technological enhancements, exterior and interior styling, powertrain, and features.

Motor or Engine Mounts: These are brackets that secure the engine and transmission to the vehicle’s frame. They contain rubber or polyurethane elements that absorb vibrations.

Mud Flaps: Mud flaps are protective accessories attached behind the wheels of vehicles like trucks, SUVs, and some types of cars. They are designed to prevent mud, rocks, water, and other road debris from being thrown onto the vehicle itself, other cars on the road, or pedestrians.

Muffler: A device used to control the noise produced by exhaust gases before they’re expelled into the air through the tailpipe. Mufflers also manage exhaust gas pressure. Some advanced systems use specially designed piping, sometimes combined with electronics, to reduce loud exhaust tones.

Natural Gas Vehicles (NGV): These are vehicles powered by compressed natural gas (CNG).

Negative Ground: See the definition for ‘ground’.

Negative Terminal: This is the battery terminal that channels electric current back to the battery. The negative terminal usually has either “NEG” or “-” marked on it.

Non-electronic Ignition System: An ignition system typically found in older vehicles equipped with carburetors that frequently required tune-ups, including the adjustment and replacement of distributor parts.

NOS (New Old Stock): Refers to new parts that were produced in the past for vehicles that are no longer in production. These parts are often used in vehicle restoration. See also OEM (Original Equipment Manufacturer).

NOx Emissions: A common term for the toxic nitrogen oxides that, if not reduced or eliminated from exhaust emissions, contribute to air pollution.

Octane Rating: A system of rating gasoline based on its ability to resist knocking in internal combustion engines. Engines with higher compression ratios require higher octane gasoline. See also cetane rating.

Odometer: An instrument on the vehicle’s dashboard that measures and displays the total distance the vehicle has travelled. Some vehicles also have a trip odometer that can be reset to zero to track the distance travelled on a particular trip.

OEM (Original Equipment Manufacturer): Refers to parts provided by the original manufacturer of a specific vehicle. See also NOS (New Old Stock), rebuild, replacement parts, and remanufactured.

Oil: A substance that lubricates and cools the engine’s moving parts while preventing rust and corrosion. Oil is available in different viscosities suitable for optimal operation in both cold and hot weather and for engines in varying conditions of wear. See also viscosity.

Oil Change: A routine maintenance procedure for vehicles wherein the old engine oil is drained and replaced with new, clean oil to ensure proper lubrication and optimal engine performance. Typically recommended at regular intervals, determined by either a set number of miles driven or a specific time period, to maintain engine health and prolong its lifespan.

Oil Drain Plug: A plug that seals the drain hole in the oil pan. In many vehicles, an oil plug gasket is positioned between the plug and the hole and should be replaced if a leak occurs. In others, no gasket is required because the metal-to-metal connection between the drain plug and the oil pan is tapered, ensuring a leak-free seal.

Oil Filler Hole: An opening located at the top of the engine, through which new oil can be added after the filler hole cover is removed.

Oil Filter: A canister-like device attached to the exterior of the crankcase that cleans oil as it circulates through the lubrication system. Oil filters should be replaced with every oil change.

Oil Pan: The reservoir at the base of the crankcase that stores oil. The oil drain plug at the bottom of the oil pan can be removed to allow old oil to be drained from the car during an oil change.

Oil Pressure Gauge: A dashboard instrument that displays the oil pressure as the oil is pumped through the engine. If this gauge indicates a significant drop, reads “low”, or illuminates, stop the car immediately and investigate the cause of the loss of oil pressure before proceeding. A low indication doesn’t necessarily mean that the oil level in your oil pan is low; it could signify a defective or failed oil pump, among other things. See also Malfunction Indicator Light (MIL).

Oil Pump: A small pump housed in the crankcase that circulates oil from the oil pan to the moving parts of the engine.

Onboard Computer: One of numerous computers potentially present in a vehicle, responsible for controlling ignition systems, fuel systems, heating, ABS, airbag deployment, electronic stability control, traction control, rollover stability control (RSC), seat belt pre-tensioning, and other systems. See also ECU (Engine Control Unit), electronic sensing devices, sensors, system management computers.

Optional Equipment: Any feature or piece of equipment on a new vehicle that isn’t included in the base price and is provided only if the buyer requests it. Be wary of new car deals that require you to purchase a vehicle equipped with options you don’t need.

Original Condition: Describes an older vehicle that retains all its original paint and equipment and hasn’t been restored or modified.

Overdrive: A unique gear that allows the rear wheels to rotate faster at the same engine RPM, which reduces fuel consumption during prolonged high-speed driving on highways.

Overhead Cam (OHC): A camshaft located above the cylinder head. Overhead camshafts eliminate the need for push rods to activate the valves. Double overhead cam (DOHC) engines have two overhead camshafts: one for operating the intake valves, and the other for operating the exhaust valves.

Overload: The act of operating or loading a vehicle beyond its specified capacity or limits, whether in terms of weight, performance, or system demands. Examples include: Cargo and Payload Overload: Exceeding a vehicle’s designed payload capacity. Towing Overload: Towing weights beyond a vehicle’s towing capacity. Engine Overloading: Forcing an engine to operate beyond its intended limits. Electrical Overload: Drawing excessive current from the vehicle’s electrical system. Brake Overloading: Hindering brake efficiency due to excessive weight or demand. Tire Overloading: Exceeding the weight specifications for a vehicle’s tires.

Owner’s Manual: A handbook provided by the car manufacturer to give the owner basic instructions for operating the various devices on a vehicle. Many owner’s manuals contain specifications for items associated with maintenance, but very few offer DIY instructions. See also service manual.

Ozone Checking: Cracks or hard spots typically found on the sidewalls of tires. Caused by the ozone in the air reacting with the rubber, this condition is normal but could be dangerous on tires that have travelled more than 40,000 miles or that have been exposed to ozone for a long period.

Painting: The process of applying colored coatings, usually in the form of liquid paint, to the exterior and occasionally interior surfaces of vehicles to enhance their appearance, protect against environmental factors, and prevent corrosion.

Examples include:

• Base Coat: The primary color layer applied to the vehicle, which gives it its main hue.
• Clear Coat: A transparent protective layer applied over the base coat to provide shine and added protection.
• Primer: The first layer of coating applied to the vehicle’s surface to ensure better paint adhesion and corrosion protection.
• Touch-up Painting: Small-scale application of paint to cover scratches, chips, or minor damages.

Parking Brake: An auxiliary brake, usually connected to a rear wheel or to the transmission, that prevents the vehicle from moving unintentionally. Also known as an emergency brake.

Passenger door: The door or doors located on the side or sides of a vehicle, specifically designed for the entry and exit of passengers. It contrasts with the driver’s door, which is exclusively for the driver’s use.

Passing Gear: A gear in automatic transmissions that momentarily shifts a vehicle into a lower gear for a quick burst of extra power to overtake other vehicles on the highway. This gear is engaged by sharply pressing the gas pedal. When the pedal is released, the car reverts to a normal driving gear.

PCV Valve: Part of the Positive Crankcase Ventilation system, which routes unburned crankcase gases (blow-by) back to the intake manifold and then into the engine cylinders where they’re re-burned as part of the fuel/air mixture. This action reduces emission pollution and increases fuel economy because the unburned fuel in the blow-by is burned a second time. It also prevents blow-by and water vapor from contaminating the oil in the crankcase.

Pedal Free-Play: The distance the clutch pedal can be pushed down before it starts to disengage the clutch. About 1/4 to 1 inch of pedal free-play is typically necessary to ensure that the clutch will be fully engaged when not in use. Lack of pedal free-play can lead to premature wear of the throw-out bearing and/or the clutch.

Piston: A cylindrical component, sealed at the top, that moves up and down within the cylinder to compress the fuel/air mixture and power the engine. It is connected to a connecting rod, which in turn is connected to the crankshaft. See also journal and piston rings.

Piston Rings: Metallic rings located in grooves on the piston’s exterior. They prevent the fuel/air mixture from leaking past the piston into the crankcase during compression and stop oil from entering the combustion chamber. Faulty rings can result in poor compression, severe blow-by, and excessive tailpipe smoke.

Planetary-Gear System: A gear system used in some automatic transmissions that includes a central sun gear surrounded by two or more smaller planetary gears that mesh with a ring gear.

Polymer Coating: A coating that prevents paint oxidation, thereby protecting a car from premature fading and rusting. DIY polysealants can last from six months to a year, while professionally applied polyglycotes are claimed to last two to five years but haven’t been in use long enough to validate these claims. See also clear coat.

Positive Terminal: The battery terminal that connects to the vehicle’s electrical system in negative ground vehicles. The positive terminal usually has “POS” or “+” on it. Jumper cables and other battery-connected devices typically have red clips for the positive terminal and black clips for the negative terminal and ground.

Power Brakes: A braking system that utilizes a power booster to simplify braking.

Power Steering: A system that employs hydraulic power to assist the driver in steering with ease. Vehicles with power steering usually feature a reservoir in the power-steering pump, which occasionally needs topping up with power-steering fluid (sometimes automatic transmission fluid).

Powertrain Control Module (PCM): A computer that manages the operation of the fuel, ignition, and emissions control systems in newer vehicles. Also known as an electronic control module (ECM).

Powder Coating: Powder coating in the automotive context refers to a dry finishing process used to create a durable and protective finish on various car parts, including wheels, bumpers, engine parts, and other accessories. Unlike traditional liquid paint, powder coating is applied as a free-flowing, dry powder that is electrostatically charged. The charged powder particles adhere to the electrically grounded surfaces until they are heated and fused into a smooth coating in a curing oven. This process results in a high-quality, durable, and attractive finish that is more resistant to chipping, scratching, fading, and wear compared to conventional paint. Powder coating is available in a wide range of colors and finishes, allowing for customization and enhanced aesthetics.

Power mirror: A power mirror in automotive terminology refers to a side-view mirror that can be adjusted electronically. This feature allows drivers and passengers to adjust the angle and orientation of the vehicle’s exterior mirrors from inside the cabin without the need to manually touch the mirrors. Power mirrors are operated via buttons or a joystick-like control typically located on the driver’s door panel or on the center console. These mirrors enhance convenience, safety, and comfort by enabling easy adjustments to optimize the field of view according to the driver’s preference and seating position. In addition to basic adjustments, some power mirrors may include additional features such as heating (to clear frost, ice, or fog), folding capabilities (for narrow spaces or car washes), and memory functions (to recall preferred positions for different drivers).

Precombustion Chamber: A small chamber located outside the combustion chamber in some vehicles, where a small amount of rich fuel/air mixture can be ignited to initiate the combustion process, improving fuel efficiency and reducing emissions. Primarily found in diesel engines and certain older gasoline engines. Also known as prechambers.

Pressure Cap: A type of radiator cap used in a coolant recovery system or radiator that allows the cooling system to operate under pressure at higher temperatures, improving efficiency. Safety pressure caps are designed to help release pressure before the cap is removed to prevent injuries from escaping steam or hot coolant.

Pressure Plate: A disc that is pushed by springs against the clutch disc. This forces the disc and the engine flywheel against each other, causing the engine and the transmission to turn at the same speed. See also clutch.

PSI: An abbreviation for Pounds per Square Inch, a measurement of pressure. This term is used to measure air pressure in tires, the amount of compression of the fuel/air mixture in the combustion chamber, and more. In the metric system, pressure is measured in kilograms per square centimeter.

Push Rods: These are rods that run between the camshaft lifters and the rocker arms. The cam lobes push up the lifters and the push rods, which then cause the rocker arms to open and close the valves. Engines with overhead cams don’t require push rods because the camshaft cam lobes contact the valves or rocker arms directly.

Race: A metal ring that surrounds the balls or rollers of a wheel bearing, allowing them to turn against its smooth surface.

Radiator: A device that cools the liquid in the cooling system by allowing it to circulate through a series of water channels that are exposed to air ducts.

Radiator Fill Hole: An opening at the top of the radiator through which a 50-50 mix of water and coolant can be added if there’s no coolant recovery system. The pressure cap seals the fill hole.

R&R: A common term used by service facilities for “removal and replacement” of parts to access the site of needed repairs.

Ratchet: A device that allows you to turn a screw or bolt in one direction and then move the handle of the wrench or screwdriver back, without force, in the opposite direction to prepare for the next stroke without removing the tool from the screw or bolt. See also Socket Wrench.

Rear Axle Ratio: The number of times the rear wheels turn compared to a particular transmission speed. The higher the rear axle ratio, the slower the engine can run while still allowing the vehicle to achieve a given speed.

Rear-Wheel Drive: A vehicle that’s propelled by its rear wheels rather than pulled by its front wheels has rear-wheel drive. See also Front-Wheel Drive, All-Wheel Drive, and Four-Wheel Drive.

Rebuild: The process of disassembling a device, cleaning it thoroughly, replacing worn parts, and reassembling it. This is commonly done for engines, clutches, carburetors, and brakes as part of the maintenance or restoration of older vehicles. See also remanufactured.

Regenerative Braking System: A braking system found on electric vehicles (EVs) and hybrid vehicles that generate energy and feed it back into the battery that powers the electric motor. See also brake system.

Remanufactured: A part or engine that has been completely refurbished with new parts, unlike a rebuild, where only worn or defective parts are replaced.

Replacement Parts: Parts made by independent companies called aftermarket suppliers. These parts can range from poor to as good as original equipment manufacturer (OEM) parts.

Repossession: The act of a lender taking back a vehicle from the borrower due to the failure to make scheduled loan or lease payments as agreed upon in the contract. Repossession typically occurs after the borrower has defaulted on the loan, following a grace period and any required notifications. The repossessed vehicle is often sold at auction to recover the unpaid debt.

Resonator: A small auxiliary muffler found on some vehicles that further reduces the noise of the escaping exhaust gases, or “tunes” the exhaust tone, to make a four-cylinder engine sound more like a V-8, for instance.

Restoration: The process of restoring a vehicle to its original condition, including original parts, paint, rechroming, and so on, rather than merely rebuilding or repairing one. This can also involve repairing, replacing, and refinishing various parts of the vehicle.

Retreads: Used tires that have been refurbished by grinding off the tread and replacing it. The quality of retreads can vary; to be safe, only buy retreads from well-known manufacturers.

Rocker Arm Cover: A metal lid located on top of the cylinder head on vehicles that have valves activated by an overhead cam or rocker arms. See also valve cover.

Rocker Arms: Curved levers, each of which has one end contacting a push rod and the other end bearing on a valve stem to operate the valves.

Rollover Stability Control (RSC): A safety system that detects situations in which a vehicle taking a turn too sharply or too fast could roll over, and then helps to prevent the rollover.

Rotor: A device on vehicles with ignition systems with distributors that sits on top of the distributor shaft and rotates with it to conduct electric current to each spark plug terminal in turn. The discs on disc brakes and the triangular device inside a rotary engine are also referred to as rotors.

Rubber: All the rubber seals, mats, and pads that cushion and protect car windows, trim, handles, bumper sections, carpets, and so on. A restoration should include replacement of all damaged or missing rubber with OEM (original equipment manufacturer) rubber parts or exact reproductions.

Rubbing Compound: A polish containing abrasives harsh enough to remove layers of dead paint. It’s useful in radical restoration procedures, but shouldn’t be used on new vehicles with clear coats or delicate finishes.

Safety Hazards: Potential sources of harm or injury associated with the design, use, maintenance, or the environment surrounding vehicles. These can arise due to:

1. Vehicle Design and Manufacturing: Defects or flaws during the design or manufacturing process that can lead to malfunction or unsafe conditions.
2. Operational Issues: Dangers linked to driving behaviors, such as distracted or impaired driving, speeding, or not wearing seat belts.
3. Maintenance and Wear: The failure to regularly service a vehicle or the natural wear and tear over time that might compromise safety, such as worn-out brake pads, gas spills or bald tires.
4. Environmental Factors: Situations where external conditions pose risks, like slippery roads due to rain or ice, or poor visibility because of fog.
5. Electrical and Electronic Systems: Faults or failures in a vehicle’s electrical or electronic systems that can lead to fires, malfunctions, or loss of critical functions.
6. Collisions and Impact: The inherent risks when vehicles collide with other vehicles, pedestrians, animals, or stationary objects.

Sealed Beam Unit: A headlight that contains high- or low-beam filaments or both, a reflector, and a lens. It is sealed to keep out dirt and moisture. When the headlight fails, you replace the entire unit.

Sealer: A substance added to the liquid in the cooling system to seal small leaks; also called stop-leak. Other kinds of sealing compounds are used to coat surfaces before installing hoses or gaskets.

Sensors: Electronic devices that monitor conditions such as fuel pressure, intake air temperature, throttle position, wheel speed with anti-lock braking systems (ABS), electronic stability control, rollover stability control (RSC), and traction control systems, engine speed, and load.

Sensor Fuel Pressure: A Sensor Fuel Pressure, often referred to as a Fuel Pressure Sensor, is a device used in internal combustion engines, primarily in automotive applications, to monitor the pressure of fuel in the fuel rail. This information is crucial for the engine’s electronic control unit (ECU) to regulate and maintain optimal fuel pressure.

Service Manual: A handbook published by a car manufacturer or a specialized publishing company that contains instructions and specifications for the maintenance and repair of specific vehicles.

Service Writer: The person responsible for estimating the nature and cost of repairs and when the work will be completed for vehicles brought to the service department at dealerships.

Shims: Thin pieces of metal used between parts to fill gaps or level them.

Shock Absorbers: Devices located near each wheel to cut down the vertical bouncing of the passenger compartment when the wheels go over a bump or the vehicle stops short.

Sludge: A combination of oxidized oil, gasoline, coolant, and blow-by that can foul an engine. Modern engine oils have detergents to break down sludge.

Smooth ride: A vehicular experience where passengers feel minimal vertical motions, often a result of well-maintained road surfaces, advanced vehicle suspension systems, or optimal tire conditions.

Socket Wrench: A wrench that completely covers the head of a bolt rather than fitting around its circumference. A socket set usually consists of a variety of sockets, at least one handle (usually a ratchet handle), a couple of extenders, and sometimes a spark plug socket as well.

Solenoid: A device connected to electrical current that induces mechanical movement in another device. See also starter solenoid.

Sound Deadening Material (for Vehicles): Sound deadening material for vehicles refers to a range of products designed to reduce or dampen unwanted noise and vibrations within the automotive cabin. These materials work by absorbing, blocking, or isolating sounds and can significantly enhance the driving experience by making the vehicle’s interior quieter. The material may also improve the performance of in-car audio systems.

Spark Plug: A device that delivers the electrical spark to the combustion chamber. The spark ignites the fuel/air mixture and produces the power that drives the engine. See also ignition system, and spark plug gap.

Spark Plug Gap: The space between the center and side spark plug electrodes, across which the spark must jump to ignite the fuel/air mixture in the combustion chamber.

Spark Plug Socket: A metal cylinder with a rubber lining that fits over the exposed end of the spark plug to make it easy to remove the plug without damaging its porcelain surface.

Spare Tire: A spare tire, also known as a spare, is an additional tire carried in a vehicle as a replacement in the event of a flat tire. There are two main types: a full-size spare, which is the same size as the other tires on the vehicle, and a compact temporary spare, commonly referred to as a “donut.” The spare tire’s purpose is to allow the driver to continue their journey after a flat or damaged tire until the original tire can be repaired or replaced. It’s essential to note that spare tires, especially “donuts,” are designed for temporary, short-distance use and at reduced speeds.

Specifications: The size, description, or part numbers for various items needed to maintain or repair a vehicle; often referred to as specs.

Speedometer: A dashboard device that measures and indicates how fast the vehicle is going.

Spindle: The small shaft located at each front wheel on which the front wheels revolve on rear-wheel drive vehicles.

Splash Shield: A removable device found on disc brakes that helps to keep water and dirt from fouling the brakes.

Springs: Devices to cushion and absorb shocks and bumps and to keep the vehicle level on turns.

Stabilizers: A variety of devices used to keep the passenger compartment of a vehicle from swaying and lurching on sharp curves and turns. Also known as sway bars. See also suspension system.

Starter: A small electrical motor that causes the engine crankshaft to begin to turn, which starts the engine running and so starts the car. See also starting system.

Starter Solenoid: A device that uses electrical current to start and engage the starter.

Starting System: A subsystem in a vehicle responsible for initiating its operation, consisting of elements like the ignition switch, starter solenoid, and potentially a relay. The ignition switch enables the circuit, allowing electric current to traverse from the battery to the starter.

Steering-Axis Inclination: An alignment adjustment in a vehicle’s steering that enables the steering wheel to automatically revert to the straight-ahead position after a turn is completed.

Steering Knuckles: These are particular types of ball joints situated at the tie rods’ ends in the steering linkage. They are lubricated using grease fittings.

Steering Linkage: The assembly that connects the steering wheel with the vehicle’s front wheels, facilitating directional changes as per the driver’s inputs. This system contains grease fittings to mitigate wear and tear, and to reduce friction.

Steering Ratio: A measure that quantifies the relationship between the steering wheel’s turn and the corresponding angular turn of the wheels.

Steering System: A combination of mechanical linkages and gears connecting the driver’s input via the steering wheel to the vehicle’s wheels.

Stick Shift: Another term used to refer to the gearshift of a vehicle.

Straight Engine: Also known as an in-line engine, this configuration of cylinders in an engine is arranged in a single row.

Stroke: The vertical displacement of the piston within the cylinder of an engine, from its topmost to its bottom-most position (or vice-versa). It’s an essential aspect of the four-stroke power cycle in an internal combustion engine.

Strut: A specific type of shock absorber that contributes to a vehicle’s suspension system.

Supercharging: A technique to boost an engine’s power output by forcing larger amounts of air into the engine’s cylinders using a belt-driven air compressor or blower. This method, unlike turbocharging, reduces fuel economy as it does not use exhaust-driven turbines for air compression.

Suspension System: The assembly in a vehicle responsible for absorbing the impact of irregularities on road surfaces, thereby providing a smoother ride to the passengers. Key components of this system include springs or torsion bars, shock absorbers, control arms, and stabilizers.

SUV: An SUV, or Sport Utility Vehicle, is a category of motor vehicles that combine elements of road-going passenger cars with features from off-road vehicles, such as raised ground clearance and four-wheel drive. SUVs are typically characterized by their capacity to accommodate more passengers and cargo compared to a sedan, robust build, higher seating position, and a more spacious interior. They are often chosen for their versatility, being able to handle a variety of driving conditions and terrain, and are popular for both urban and rural driving.

Synchromesh: A device in a manual transmission that facilitates smoother gear engagement by synchronizing their rotational speeds before meshing.

System Management Computers: These are the computing units controlling various vehicle systems and features. Related components include the engine control unit (ECU), electronic sensing devices, and transmission controllers.

Tachometer: A vehicle instrument that measures engine speed in rotations per minute (RPM). Although predominantly seen in manual transmission vehicles to aid in gear shifting, they are increasingly common in automatic transmission vehicles as well.

Tailpipe: The final component of a vehicle’s exhaust system, leading the exhaust gases from the muffler towards the rear of the vehicle, releasing them into the atmosphere.

Thermostat: A temperature-sensitive device that regulates the flow of coolant to the vehicle’s heater core. As engine temperature rises, the thermostat allows hot coolant to flow through the heater core. This heat is then transferred to incoming air, which is blown into the vehicle’s cabin by the blower motor. A properly functioning thermostat ensures that the car’s heater delivers warm air to the cabin efficiently, especially during colder weather.

Throttle: A device responsible for controlling the power output of a gasoline engine by adjusting the fuel amount entering the cylinders. In mechanical systems, a throttle arm situated outside the throttle-body in fuel injection systems is linked to the accelerator pedal. In electronic or throttle-by-wire systems, a sensor on the accelerator sends signals to the fuel injection system, dictating the fuel quantity to be sprayed into the cylinders based on accelerator demand.

Throw-Out Bearing: A component of the clutch system, activated by the clutch pedal, enabling clutch disengagement. Prolonged idling in gear with the clutch pedal depressed, instead of shifting to neutral, can lead to wear and tear of this part, also known as the clutch release bearing.

Tie Rods: Components of a rack-and-pinion steering linkage, connecting the steering rack to the steering arm.

Timing: An essential characteristic for vehicle performance, referring to the coordination between various engine-driven parts such as valves, ignition systems, etc., for maximum efficiency. In older cars, timing checks form part of a basic tune-up to ensure optimal performance.

Timing Belt: A toothed belt, driven by the crankshaft, operating the overhead cam or camshafts and in some vehicles, the water pump. It’s recommended to replace this belt as per the vehicle’s maintenance schedule provided in the owner’s manual.

Timing Chain: A chain driven by the crankshaft that operates the camshafts, in turn opening and closing the intake and exhaust valves. In many modern vehicles, this part has been replaced by a timing belt.

Tire Valve: A small valve fitted on the wheel rims of tires, facilitating air addition to or release from the tire using a properly equipped air hose.

Tires: Essential components of a vehicle, providing crucial traction for braking, accelerating, and cornering, on wet or dry surfaces. They also significantly influence ride quality. Modern passenger vehicles predominantly use radial tires, reinforced with materials like polyester, fiberglass, steel, or nylon.

Tire Pressure: The measure of the amount of air inside a vehicle’s tire, typically expressed in pounds per square inch (psi), bar, or kilopascals (kPa). It is a crucial parameter affecting vehicle performance, safety, and tire longevity. Optimal Pressure is specified by vehicle manufacturers for best performance and safety. Over-inflation is a condition where the tire contains more air than recommended, potentially leading to a rough ride and increased wear in the center of the tire. Under-inflation is a condition where the tire has less air than recommended, resulting in increased wear on the tire’s edges, reduced fuel efficiency, and compromised handling.

Tire Rotation: A routine vehicle maintenance procedure that involves moving tires from one position on a vehicle to another to ensure even tire wear. Typically, the front tires are moved to the rear and vice versa, often crisscrossed in the process. Regular tire rotations can extend the lifespan of the tires, improve fuel efficiency, and provide smoother, more balanced driving. It is recommended to perform a tire rotation every 5,000 to 7,000 miles, though this can vary based on the vehicle and tire specifications.

Toe-In: A front-wheel alignment adjustment ensuring the tires are slightly inward-facing (pigeon-toed) when the vehicle is stationary. This configuration is necessary for proper steering and tire wear.

Toe-Out: A wheel alignment angle employed to control the vehicle’s tracking during turns. It’s not recommended to have tires in a permanent toe-out configuration.

Torque: A measure of turning or twisting force. It is often measured using a torque wrench.

Torque Converter: A component in an automatic transmission, often referred to as a fluid coupling, that transfers power from the engine to the transmission input shaft.

Torque Wrench: A specialized wrench used to measure and apply a precise amount of torque while tightening a nut or bolt.

Torsion Bars: These are components of a vehicle’s suspension system.

Traction Control System (TCS): A feature that automatically applies brakes, cuts off power, or reduces acceleration to a wheel spinning faster than others, thereby improving traction and maintaining stability.

Trailer-Towing Packages: These are optional features that generally include a heavy-duty suspension, a larger radiator, and a trailer hitch-equipped rear bumper with wiring for the tow vehicle’s lights.

Transaxle: A combined unit of transmission and differential, directly connecting to the driveshafts in front-wheel drive or rear-engine vehicles.

Transfer Case: A unit in four-wheel drive vehicles, situated between the transmission and driveshaft, governing power distribution to the front and rear drive axles when switching between two-wheel and four-wheel drive.

Transistor: A small electronic component without moving parts, with at least three connections, acting as a switch or amplifier to regulate current flow.

Transmission: An assembly of toothed gears that mesh in various combinations, enabling a vehicle to move forward and backward with varying degrees of power in different driving situations. Manual transmissions use a clutch and gearshift, whereas automatic transmissions use hydraulic pressure.

Transmission Controller: A computer in electronic transmissions monitoring engine speed, load, and other factors to control gear shifting.

Transmission Fluid: A specific type of oil filling the automatic transmission to facilitate operation based on hydraulic pressure. This fluid is also present in many power-steering pumps.

Transmission Input Shaft: The rotating shaft that delivers power from the engine and torque converter or clutch into the transmission.

Transmission Output Shaft: The shaft transferring power from the transmission to the driveshaft.

Transverse Engine: An engine mounted between the drive wheels with cylinders arranged parallel to the wheels. Predominantly seen in front-wheel-drive vehicles.

Trim: Non-functional decorative additions made of metal or plastic, attached to vehicle bodies and interiors.

Trunk: A designated storage compartment located typically at the rear of a vehicle, separate from the passenger compartment. Used for storing luggage, tools, and other items.

Turbocharging: Utilizing an exhaust-powered turbine to compress air and propel it into the engine cylinders, thereby increasing the engine’s power.

Turning radius: A measurement indicating the tightness of a vehicle’s turning capability when the steering wheel is fully turned in one direction.

U-joints: An abbreviated term for universal joints, which are couplings located at each end of the driveshaft in a rear-wheel drive vehicle. These joints enable free movement of the driveshaft without impacting the more rigid transmission shaft, while also accommodating the axle and wheel movement. In cars with transverse engines, these joints are referred to as constant velocity joints (CV).

Undercoating: A protective substance applied to the underside of new vehicles to prevent the formation of rust.

Upholstery: The materials used to cushion and cover furniture, especially seats, often consisting of padding, springs, webbing, fabric, or leather. In automotive contexts, it refers to the fabric or leather covering on car seats and interior trims.

Vacuum modulator: A component found in some older automatic transmissions, responsible for regulating the pressure in the transmission’s hydraulic system. Malfunctioning vacuum modulators can mimic transmission issues or result in transmission fluid leakage into the intake manifold, leading to smoke emission from the tailpipe.

Valve cover: A metal cover situated on top of the cylinder head in vehicles with overhead valves. The valve cover is removed when the adjustable valves require adjustment.

Vacuum Leak: A condition that occurs when an engine’s intake system has a breach or a leak, allowing unmetered (unregulated) air to enter into the system. This disruption can impact the balance of the air-fuel mixture that the engine requires for proper operation, leading to various problems including idle instability, poor fuel economy, and reduced engine performance. Vacuum leaks commonly originate from damaged or disconnected hoses, gaskets, or seals.

Valves: Located within the cylinder head, valves open and close to allow the entry of fuel and air into the combustion chamber, as well as the expulsion of exhaust gases. Valve operation involves valve lifters, push rods, rocker arms, and lobes on an overhead camshaft, while springs assist in closing the valves. See also exhaust valve, intake valve, timing belt, and timing chain.

Vaporize: The process of converting a liquid into a mist by breaking it into small particles and mixing it with air. Fuel injector nozzles spray minute quantities of gasoline or other fuel into the combustion chamber, causing it to vaporize and create a combustible fuel/air mixture.

Viscosity: The thickness or flowability of a liquid. Oil is available in various thicknesses, known as weights, including single viscosity (single-weight oil) and blends of viscosities (multi-weight oil). Multi-weight oil facilitates easy flow in cold weather while reducing thinning in hot weather. The higher the weight, the greater the viscosity of the oil. The weight of the oil can be found on the packaging.

Voltage regulator: An electrical device that controls or regulates the electric voltage generated by the alternator. In many vehicles, this is an integrated part of the alternator rather than a separate component, or this function may be performed by the Powertrain Control Module (PCM).

V-type engine: An engine configuration in which the cylinders are arranged in two rows set at an angle to each other, with the crankshaft running through the point of the “V.” V-type engines are identified by the number of cylinders, such as V6, V8, etc.

Warning lights: Also known as malfunction indicator lights (MIL), these lights are used to indicate a problem or malfunction in the vehicle’s systems or components.

Warranty: A promise made by an automaker or dealership to repair or replace parts on a new vehicle if they malfunction within a specific time or distance.

Water jackets: Channels within the engine through which water and coolant (antifreeze) circulate to cool the engine. They are part of the cooling system.

Water pump: A device that circulates the coolant through the cooling system by pumping it from the engine’s water jackets to the radiator.

Water separator: A device found in diesel vehicles that removes any water that may have contaminated the diesel fuel.

Wiper blade: A wiper blade is a device used on vehicles, such as cars, trucks, and buses, to remove rain, snow, ice, and debris from the windshield. It is an essential component of a vehicle’s windshield wiper system. Wiper blades are typically made of a metal or plastic frame that holds a rubber or silicone blade. They are attached to the wiper arms, which are powered by an electric motor, enabling the blades to move back and forth across the windshield. This movement helps maintain clear visibility through the windshield by clearing off any obstructions. There are several types of wiper blades, including traditional bracket blades, beam blades, and hybrid blades, each designed to cater to different weather conditions and windshield shapes.

Wheel alignment: Also referred to as alignment, it is the adjustment of the angles of the wheels to ensure they are parallel to each other and perpendicular to the ground. Proper wheel alignment promotes even tire wear and optimal handling.

Wheel balancing: A procedure that ensures even distribution of weight on a wheel and tire assembly, resulting in smooth vehicle movement with no vibrations in the steering wheel or other areas. It involves placing the wheel and tire assembly on a balancing machine to detect imbalances and attaching small weights to the rim to achieve balance, especially at higher speeds.

Wheel bearings: The inner and outer bearings located at each wheel that provide a cushioning effect between the wheel and the spindle it sits on. They are lubricated with grease to prevent wear caused by the friction of the rotating wheels.

Wheel cylinder: In drum brake systems, a small cylinder located at each wheel brake that uses brake fluid to exert hydraulic pressure. This pressure forces the brake shoes against the brake drums, leading to vehicle deceleration and stopping. See also calipers.

Winch: A mechanical device used for pulling, lifting, or lowering objects. Typically mounted on the front or rear of a vehicle, a winch consists of a motor, a cable or rope, and a spool around which the cable is wound. In automotive applications, winches are commonly used for vehicle recovery, such as pulling a stuck or disabled vehicle out of mud, snow, or other difficult terrain. They may also be used for towing objects, hauling loads, or other pulling tasks. Winches can be powered manually, but most modern vehicle-mounted winches are electrically or hydraulically operated.

Windshield: A windshield is a front-facing window in an automobile or other type of vehicle. Its primary function is to protect the vehicle’s occupants from wind, temperature extremes, and flying debris such as dust, insects, and rocks. Modern windshields are generally made of laminated safety glass, a type of treated glass that consists of two (typically) curved sheets of glass with a plastic layer laminated between them for safety.

Windshield Washer Fluid: Windshield washer fluid is a liquid solution used in vehicles for the purpose of cleaning the windshield while the vehicle is being driven. It increases visibility through the windshield by cleaning dirt, dead insects, and other debris. The fluid is filled into a tank (known as the windshield washer reservoir), usually located under the hood of the vehicle. It’s distributed over the windshield through small nozzles and wiped off by the windshield wipers. This fluid often includes detergents, solvents, and antifreeze (in colder climates). Variations include fluids for all-season use, bug repellent, de-icer, and water-repelling properties.

Car’s AC System: A/C stands for Air Conditioning. It refers to the system within a vehicle that cools, purifies, and circulates air within the cabin, providing comfort to the vehicle’s occupants in warm weather. The A/C system works by removing the heat and humidity from the air inside the car, cooling and dehumidifying it, and then blowing it back into the cabin. Components of the A/C system typically include the compressor, condenser, evaporator, orifice tube or expansion valve, and refrigerant.

Evaporator: Located inside the vehicle, the evaporator serves as the heat absorption component. The refrigerant in the evaporator coil evaporates as it absorbs heat from the interior of the car, cooling the surrounding air in the process.

Refrigerant Levels: This refers to the amount of refrigerant gas (commonly Freon) present in the car’s AC system. Maintaining correct refrigerant levels is crucial for optimal functioning of the AC system. Too much or too little refrigerant can negatively impact the AC’s ability to cool the car’s interior.

Condenser: The condenser is typically located in front of the car’s radiator. It functions similar to a radiator, dissipating heat. However, instead of engine coolant, the condenser dissipates heat from the refrigerant. The refrigerant arrives in the condenser as a high-pressure gas from the compressor, and it leaves as a high-pressure liquid after releasing its heat.

Expansion Valve: The expansion valve, also known as an orifice tube in some systems, controls the amount of refrigerant going into the evaporator. It also depressurizes the refrigerant, turning it into a low-pressure, low-temperature gas and allowing it to cool down before entering the evaporator.

Drain Tube: This component, also known as the AC drain hose, removes condensation produced by the AC’s evaporator coil. If the tube becomes clogged, water can back up into the interior of the vehicle, often causing wet carpeting or a damp smell.

Compressor: The compressor, often termed as the “heart” of the car’s AC system, is a pump that pressurizes and circulates refrigerant throughout the AC system. It’s powered by the engine via a serpentine belt, and it cycles on and off as needed to maintain the desired temperature inside the vehicle.