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Ca     Ch     Ci     Cl    Co     Cr     Cu     Cy

Caliper   The apparatus on disc brakes which hold the disc pads and straddles the disc. When actuated the pads press against the disc to stop or slow the vehicle.


[1] A designed bump on a shaft or disc which causes a rocking motion in an adjacent part.

[2] A metal disc with irregularly shaped lobes used in the camshaft to activate the opening and closing of the valves and in the distributor, to force the points to open.

[3] A colloquial name for the camshaft.

[4] A name for the breaker cam.

cam lobe
cam lobes The bumps on a cam that contact and activate such devices as the lifters, which operate the valves, and the rubbing block, which causes the points to open and close, as the cam spins with the distributor shaft.

Camshaft A rotating shaft on which a series of cam lobes operate the valve mechanisms. The camshaft may be driven by gears, by sprockets and chain or by sprockets and a belt.

Canister A container in an evaporative emission control system; contains activated charcoal granules to trap vapors from the fuel system.

Carburetion  The mixture of vaporized fuel and air in the proper proportions for combustion in an engine

Carburetor Optionally spelled "carburetter" or "carburettor."

A device that vaporizes fuel and mixes it with air in proper quantities and proportions to suit the varying needs of the engine. A filter screens the air which is drawn into the carburetor. Here the gasoline mixes with the air and this fuel vapor enters the combustion chamber through the intake valve where it is compressed and burned.


Carburetor Kit A set of gaskets and parts necessary to rebuild a carburetor.

Castor In wheel alignment, the backward or forward tilt of the steering axis. Castor is positive when the steering axis is inclined rearward at the top.

Catalytic converter A silencer-like device in the exhaust system which converts certain pollutants in the exhaust gases into less harmful substances.

Chain Drive  The driving of one shaft by another by means of a toothed wheel on each shaft, with the wheels connected by an endless chain with special links engaging the teeth.

Chassis The basic-strength auto frame including the engine, suspension, wheels, brakes and drive train. A car without its body or coachwork. In monocoque or unit construction it is integral with the body.


'Check engine' light  

Almost all modern vehicles have a computer to control the operation of the engine and transmission (sometimes it is called Powertrain Control Module [PCM] or Electronic Control Module (ECM) or something alike). There are also various sensors all over the engine and transmission (such as coolant temperature sensor, speed sensor, exhaust oxygen sensor, airflow sensor, etc.) that give input to the computer. Using this input, the computer maintains the highest engine efficiency with the lowest possible emissions. When the signal from any of the sensors is wrong or beyond the limit, the computer lets you know by turning the "check engine" light on. It can mean anything: broken sensor wire, loose connection, bad gasoline, clogged fuel injector, bad catalytic converter, etc. Most often it's related to the emission control components. On newer cars the 'check engine' light will come on even if you simply forget to close the gas cap. If the "check engine" light is on, this means the computer has stored the trouble code(s) in its memory. The trouble code points to the defective part. All you need to do is have a dealer scan the vehicle computer with a diagnostic scanner and get this code. The code will show exactly what's wrong, or at least will give the technician the direction where to look for.

Choke  A mechanism, either manual or automatic, whose purpose is to supply an enriched fuel mixture to a carbureted engine to aid in cold starting. It effectively reduces the amount of air allowed into the intake manifold through the carburetor.

A temporary restriction in a carburetor throat that reduces the flow of air and enriches the fuel-air mixture to aid in starting the engine.

A butterfly valve or plate located near the top of the carburetor that limits or restricts the amount of air allowed to enter the carburetor, thus enriching the fuel-air mixture and enabling the vehicle to start and run more easily when cold. Automatic chokes have a thermostatic coil or thermostatic spring that activates a butterfly valve at the top of the carburetor barrel. Older cars have manually operated chokes. Some vehicles use an enrichner instead of a choke.

Circlip A ring-shaped clip used to prevent endwise movement of cylindrical parts and shafts. An internal circlip is installed in a groove in a housing; an external circlip fits into a groove on the outside of a cylindrical piece such as a shaft.

Cluster Panel The reverse side of the instrument panel or dash where all the wiring or circuit board is located.

Clutch   A drivetrain component that connects an engine to a manual transmission and is used to engage transmission gears. It also allows the transmission to be


disconnected from the engine, so the vehicle can sit still with the engine running. A clutch is a friction mechanism that typically consists of a disc and pressure plate assembly. To engage the clutch, the driver simply applies pressure to the clutch pedal. The linkage from the pedal to the clutch can be mechanical or hydraulic.

Clutch Plate The clutch plate is a thin, steel, disc whose center is connected to the transmission input shaft by a grooved piece of metal, or hub. The disc is covered with material that is similar to the break linings. This material allows the clutch to slip smoothly and quietly.


Coil  See ignition coil

Coil Spring 

[1] A section of spring steel rod wound in a spiral pattern or shape. Widely used in both front and rear suspension systems. Like large metal bed springs, these coils cushion and absorb the shocks and bumps as the 

vehicle is driven. They are usually found near the front wheels, but some cars have them in the rear as well. Often the shock absorbers run up the center of the coil springs.

[2] A coiled metal spring used in a suspension fork. Generally considered to be plusher, but heavier, than air springs.

A spiral of elastic steel found in various sizes throughout a vehicle, for example as a springing medium in the suspension and in the valve train.

Combustion The intense burning of the fuel-air mixture in the combustion chamber. Some used to think that the fuel-air mixture exploded; but further investigation has shown that it rapidly burns. Also see combustion chamber volume, combustion chamber, combustion space, compression ignition, controlled combustion system, external combustion engine, fireball combustion chamber, hemispherical combustion chamber, internal combustion engine, main combustion chamber, pent-roof combustion chamber, pre-combustion chamber, and wedge combustion chamber.

Combustion Chamber  The space remaining at the top of the cylinder when the piston is at the top dead center position. Where the fuel-air mixture begins to burn.

The volume of the space in the cylinder above the piston with the piston at top dead center (TDC) in the compression stroke. The head of the piston, the cylinder walls, and the head form the chamber. Combustion of the fuel-air mixture begins here when ignited by a spark plug. The design and shape of the combustion chamber can affect power, fuel efficiency, and emissions of an engine.

Combustion Chamber Recess The area where combustion occurs in a rotary piston engine

Combustion Chamber Volume volume of combustion chamber (space above piston with piston on TDC) measured in cc (cubic centimetres).

Combustion Engine: See external combustion engine and internal combustion engine

Combustion Pressure: The pressure created during the combustion of the air/fuel mixture in the cylinder, measured in pounds per square inch.

Combustion Residue: Carbon and other deposits resulting from combustion.

Combustion Space  See combustion chamber.


[1] Applying pressure to a spring, or any springy substance, thus causing it to reduce its length in the direction of the compressing force.
[2] Applying pressure to a gas, thus causing a reduction in volume. [3] One of the essential factors in a internal combustion engine (fuel, air, proper proportion of mixture, compression, timing, spark). It is the squeezing of the fuel-air mixture in the cylinder of a spark-ignition engine or the squeezing of the air in a diesel engine. Compression makes the process of combustion more effective and increases engine efficiency.

Read More about Compression within the Car Engine

Compression Ratio The ratio of the cylinder volume with the piston at bottom dead center to the cylinder volume with the piston at top dead center.

Connecting Rod  The arm that connects the piston to the crankshaft and converts the reciprocating motion into rotary motion.


Discover How The Connecting Rod works in The Engine

Constant Velocity (CV) Joint  A type of universal joint that cancels out vibrations caused by driving power being transmitted through an angle.

Control Arm A front suspension component that often is shaped like the letter A and also may be called an A-arm. Two points on the control arm

(at the "bottom" of the A) attach to a vehicle's frame, while the third point attaches to the spindle. Rear control arms feature a different design but accomplish essentially the same purpose.  Both types of high-performance control arms are designed to eliminate flex, which leads to more predictable and improved handling, as well as enhanced traction capabilities.

 Some rear control arms are adjustable, as well, to allow for adjustments to the vehicle's suspension geometry.

Coolant (antifreeze) is a complex chemical liquid helps prevent freezing in cold climates, so that cars can operate in sub zero temperatures, and boils at a higher temperature than water. Besides this, it also lubricates the water pump as it flows through. Some antifreeze compounds are specially formulated for aluminum radiators. Keep the coolant somewhere between 20 and 60 percent of the mixture in your car, depending on the car and climactic conditions. Do not use a strong antifreeze mixture as it can cause leaks in your car's cooling system. Coolant is extremely poisonous and should be handled with care. If it spills on the ground it can kill stray animals that drink it.

Most commercially available antifreeze contains ethylene glycol, a chemical that helps to control the temperature of the water in a vehicle’s radiator. During its life in a vehicle, antifreeze may become contaminated with fuel or heavy metal particles and grit. If the levels of dissolved metals, such as lead or cadmium, are high enough, used antifreeze may be a hazardous waste.

Do not dispose of antifreeze down the drain, in sewers, or into streams. Never drain the antifreeze from your car onto the street. The sweet smell of antifreeze is appealing to dogs and cats, who may drink it. Antifreeze is poisonous to animals — even a small amount can kill them.

CHEMICAL CONSTITUENTS: Ethylene glycol, Lead, Toluene 

Here are some waste reduction tips:

Reduce the amount of antifreeze you use by routinely checking the radiator, reservoir, and hoses for leaks and repairing them immediately.

Avoid overfilling the radiator or reservoir. 

Extend preventive maintenance (PM) cycle. As long as a chemical analysis or an antifreeze tester reveals that your antifreeze is doing its job, don’t drain and replace it.

Do not drain antifreeze into the street, into storm drains, or onto the ground. 

Use dedicated equipment and containers to collect and store used antifreeze to avoid contamination.

Recycle used antifreeze by sending it off-site for recycling, or contracting with an on-site recycling service. Specify a totally enclosed system.

Cooling Fan

[1] A large fan designed to suck relatively cool air and force it onto a warm object like an engine.

[2] A large fan designed to pull away the radiant warm air surrounding a hot object.

Cooling Fins:

    The greater the surface area that needs to be cooled, the better you will be able to cool off a hot object, like an engine. By putting a number of fins on a surface, you increase the overall area. On air cooled engines, for instance, you will see a series of closely formed ridges or fins in parallel. As the air passes by them, the engine heat is dissipated.

Cooling Jacket       See water jacket

Cooling System  After a vehicle's engine comes up to operating temperature, its thermostat opens and the water pump begins to circulate coolant through the vehicle's engine block and out to the radiator. This helps to maintain the engine at an optimal temperature and prevent overheating.

A cooling system requires regular maintenance. Typically, the fluid must be drained, and some automakers recommend flushing the system, as well.

Refer to the owner's manual for more details.

Core Plug A disc or cup-shaped metal device inserted in a hole in a casting through which core was removed when the casting was formed. Also known as a freeze plug or expansion plug.

Corvette A vehicle, Chevy brand of which the 1953-70 models are milestone cars.

Corvette debuted in January of 1953 as a show

car in the GM Motorama. It was a stylish two-seat convertible, designed to show the world that GM could create a sports car to compete with European nameplates like Jaguar and MG. All 1953 Corvettes were Polo White with red interiors.


Cowl  That part of a car's body between the engine compartment and the driver.

C Pillar  The body post that supports the rear of the roof and to which the left and right sides of the back glass are attached.

Also called "C-post."

C Post
C-Post  see  C-pillar



The lower part of the engine block in which the crankshaft rotates. A pan or box that encloses the bottom of the engine, supports the crankshaft, and contains the oil for the engine.

  3 Cylinder Crankcase    4 cylinder crankcase     6 cylinder crankcase

Crankshaft  The main shaft of an engine with a U-shaped offset at each cylinder to which the connecting rod is attached. It delivers rotary motion taken from the reciprocating pistons and connecting rods.

Discover How The Crankshaft works in The Engine

Crocodile Clip See Alligator clip

Cubic Capacity  The volume of the cylinder between the piston top dead center and bottom dead center. Expressed in cubic centimeters or cubic inches.

Cubic Centimeter (cc)   European, metric, and competition measure of engine displacement:

1,000 cc = 1 liter, which equals about 61 cubic inches. 

Cubic Inch (cu. in.)  U.S. measure of engine displacement:

 1 cubic inch = 16.387 cc. 

Cylinder  The round chamber or hole in the cylinder block that houses the pistons and where combustion takes place. Also called "bore" or "barrel."

A device which converts fluid power into linear mechanical force and motion. This usually consists of movable elements such as a piston and piston rod, plunger or ram, operating within a cylindrical bore.

Discover How The Cylinder works in The Engine

Cylinder Block  The basic framework of the engine to which other engine parts are attached. It is usually a casting and includes the engine cylinders and the upper part of the crankcase.

See image above

Cylinder Head  The detachable part of the top of the cylinder block that contains the spark plugs and valves. It seals the cylinder and forms the top of the combustion chamber.

See image above

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The objective of this Web Page is to familiarize you with basic auto maintenance
-  in some common emergencies -
not to make you an expert in auto mechanics

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