Glossary of Terms

API: American Petroleum Institute
ASE: National Institute for Automotive Service Excellence
ATF: Automatic Transmission Fluid
AXLE: Shaft or shafts of a vehicle upon which wheels are mounted
BATTERY: Any number of complete electrical cells assembled in one housing or case
BATTERY CAPACITY: The amount of current battery can delivery
BATTERY RATINGS: Standards of power-delivering capability of batteries as established by
Battery Council of America(BCA)
BRAKE BLEEDING: Procedure for removing air from the hydraulic brake lines
BRAKE FLUSHING: A procedure for removing old brake fluid from a brake system and washing
out sediment
CCA: Cold crank amps = The number of amperes a battery at 0° F (-17.8° C) can
deliver for 30 seconds and maintain a voltage equal to or higher than 1.20 per cell.
CAMBER: Wheel alignment adjustment determining the tilt out or in of the top of
the wheel
CAMSHAFT: Shaft containing lobes or cams which operate engine valves
CARBURETOR: A device for mixing fuel with air to form a combustible mixture
CATALYTIC CONVERTER: An emission control device mounted in a cars exhaust system that reburns
engine exhaust to lower emissions
CHECK ENGINE OR SERVICE ENGINE SOON LIGHT:
A dash mounted light used to indicate a computer malfunction
CHOKE: Usually a plate on the top of a carburetor that restricts the amount of
air that can enter the carburetor when the engine is cold. (Produces richer mixture , more
gas, less air).
CRANKSHAFT: Main shaft of an engine which, in conjunction with connecting rods,
changes the up and down motion of pistons into rotating motion
CYLINDER: Round hole inside engine machined to receive a piston
CYLINDER BLOCK: Main portion of an engine to which all other parts are attached
CYLINDER HEAD GASKET: Seal used between cylinder head and cylinder block
DIRECT CURRENT: Electrical energy that flows in only one direction (Most things on an
automobile work with direct current.)
DRIVE TRAIN: All parts that produce power and deliver it to the drive wheels
ELECTRONIC FUEL INJECTION: A computer controlled fuel system that distributes fuel through fuel
injectors located in each intake port of an engine
EGR: (Exhaust Gas Recirculation System) Flows exhaust gasses back into the
combustion chamber to cool combustion and reduce oxides of nitrogen emissions
ECU: [Electronic Control Unit] The onboard computer
EMISSIONS: Harmful components of a vehicles exhaust, fuel system or crankcase vapors
emitted into the atmosphere
FLOODING: A situation where too much gas has entered the engine relative to
operating conditions
FOUR GAS ANALYZER: The equipment used to test a cars exhaust for hydrocarbons, carbon
monoxide, carbon dioxide, and oxygen.
GASKET: A substance placed between two metal surfaces to create a seal
INTAKE VALVE: A valve which permits fuel and air to enter an engine cylinder and then
blocks its exit
KNOCK: Term used to describe engine noises. Mechanical wear can cause knocking or
pre-ignition from improper fuel or engine adjustments can also cause knocking
MACPHERSON STRUT: Shock absorber unit used with a coil spring as a structural suspension
component. [It positions the wheel where a shock absorber only prevents bounce, and
serves no structural function.]
METHANOL: Wood alcohol. [POISONOUS]
OCTANE: A unit of measurement on a scale intended to indicate a fuels ability to
prevent engine knock. [Currently octane is rated by the R+M divided by 2 method]
PCV: Positive crankcase ventilation. A system which controls the flow of
crankcase vapors into the engine intake manifold where they are burned rather than
discharged into the atmosphere
PINGING: SEE Knock. Sound created when fuel burns too rapidly. The expanding fuel
hits the tops of the upward moving pistons creating the noise.
POWER TRAIN: SEE Drive Train.
PROM: The chip inside a vehicles computer that tailors the basic computer to the
vehicle [Programmable Read Only Memory]
RECIPROCATING: Back and forth movement. A piston in an engine reciprocates [Moves up and
down]
R-12: Refrigerant used in air conditioners on cars, commonly referred to as
freon [A trade name]
R-134a: New refrigerant to replace R-12 [Not compatible with R-12]
SUSPENSION: Those components under a car used to suspend the car above its wheels
TIMING BELT: Rubber belt used to drive the camshaft from the crankshaft
TIMING CHAIN: Metal chain used to drive the camshaft from the crankshaft
TORQUE WRENCH: A special wrench with an indicator to measure applied force
UNIBODY: Design used for most modern cars where frame and body structure are made
into one unit
VACUUM: Any pressure less than atmospheric pressure. [Negative pressure]
VISCOSITY: Thickness or resistance to movement of a liquid. Critical in engine oils
[Never use an oil with a viscosity other than recommended by the vehicle manufacturer.]


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