1988 OPEL CALIBRA low oil pressure

REF•10MOTTest Checks
Exhaust system
MStart the engine. With your assistant
holding a rag over the tailpipe, check the
entire system for leaks. Repair or renew
leaking sections.
Jack up the front and rear of the vehicle,
and securely support it on axle stands.
Position the stands clear of the suspension
assemblies. Ensure that the wheels are
clear of the ground and that the steering
can be turned from lock to lock.
Steering mechanism
MHave your assistant turn the steering from
lock to lock. Check that the steering turns
smoothly, and that no part of the steering
mechanism, including a wheel or tyre, fouls
any brake hose or pipe or any part of the body
structure.
MExamine the steering rack rubber gaiters
for damage or insecurity of the retaining clips.
If power steering is fitted, check for signs of
damage or leakage of the fluid hoses, pipes or
connections. Also check for excessive
stiffness or binding of the steering, a missing
split pin or locking device, or severe corrosion
of the body structure within 30 cm of any
steering component attachment point.
Front and rear suspension and
wheel bearings
MStarting at the front right-hand side, grasp
the roadwheel at the 3 o’clock and 9 o’clock
positions and shake it vigorously. Check for
free play or insecurity at the wheel bearings,
suspension balljoints, or suspension mount-
ings, pivots and attachments.
MNow grasp the wheel at the 12 o’clock and
6 o’clock positions and repeat the previous
inspection. Spin the wheel, and check for
roughness or tightness of the front wheel
bearing.
MIf excess free play is suspected at a
component pivot point, this can be confirmed
by using a large screwdriver or similar tool and
levering between the mounting and the
component attachment. This will confirm
whether the wear is in the pivot bush, its
retaining bolt, or in the mounting itself (the bolt
holes can often become elongated).
MCarry out all the above checks at the other
front wheel, and then at both rear wheels.
Springs and shock absorbers
MExamine the suspension struts (when
applicable) for serious fluid leakage, corrosion,
or damage to the casing. Also check the
security of the mounting points.
MIf coil springs are fitted, check that the
spring ends locate in their seats, and that the
spring is not corroded, cracked or broken.
MIf leaf springs are fitted, check that all
leaves are intact, that the axle is securely
attached to each spring, and that there is no
deterioration of the spring eye mountings,
bushes, and shackles.MThe same general checks apply to vehicles
fitted with other suspension types, such as
torsion bars, hydraulic displacer units, etc.
Ensure that all mountings and attachments are
secure, that there are no signs of excessive
wear, corrosion or damage, and (on hydraulic
types) that there are no fluid leaks or damaged
pipes.
MInspect the shock absorbers for signs of
serious fluid leakage. Check for wear of the
mounting bushes or attachments, or damage
to the body of the unit.
Driveshafts
(fwd vehicles only)
MRotate each front wheel in turn and inspect
the constant velocity joint gaiters for splits or
damage. Also check that each driveshaft is
straight and undamaged.
Braking system
MIf possible without dismantling, check
brake pad wear and disc condition. Ensure
that the friction lining material has not worn
excessively, (A) and that the discs are not
fractured, pitted, scored or badly worn (B).
MExamine all the rigid brake pipes
underneath the vehicle, and the flexible
hose(s) at the rear. Look for corrosion, chafing
or insecurity of the pipes, and for signs of
bulging under pressure, chafing, splits or
deterioration of the flexible hoses.
MLook for signs of fluid leaks at the brake
calipers or on the brake backplates. Repair or
renew leaking components.
MSlowly spin each wheel, while your
assistant depresses and releases the
footbrake. Ensure that each brake is operating
and does not bind when the pedal is released.
3Checks carried out
WITH THE VEHICLE RAISED
AND THE WHEELS FREE TO
TURN

MOTTest Checks REF•11
MExamine the handbrake mechanism,
checking for frayed or broken cables,
excessive corrosion, or wear or insecurity of
the linkage. Check that the mechanism works
on each relevant wheel, and releases fully,
without binding.
MIt is not possible to test brake efficiency
without special equipment, but a road test can
be carried out later to check that the vehicle
pulls up in a straight line.
Fuel and exhaust systems
MInspect the fuel tank (including the filler
cap), fuel pipes, hoses and unions. All
components must be secure and free from
leaks.
MExamine the exhaust system over its entire
length, checking for any damaged, broken or
missing mountings, security of the retaining
clamps and rust or corrosion.
Wheels and tyres
MExamine the sidewalls and tread area of
each tyre in turn. Check for cuts, tears, lumps,
bulges, separation of the tread, and exposure
of the ply or cord due to wear or damage.
Check that the tyre bead is correctly seated
on the wheel rim, that the valve is sound andproperly seated, and that the wheel is not
distorted or damaged.
MCheck that the tyres are of the correct size
for the vehicle, that they are of the same size
and type on each axle, and that the pressures
are correct.
MCheck the tyre tread depth. The legal
minimum at the time of writing is 1.6 mm over
at least three-quarters of the tread width.
Abnormal tread wear may indicate incorrect
front wheel alignment.
Body corrosion
MCheck the condition of the entire vehicle
structure for signs of corrosion in load-bearing
areas. (These include chassis box sections,
side sills, cross-members, pillars, and all
suspension, steering, braking system and
seat belt mountings and anchorages.) Any
corrosion which has seriously reduced the
thickness of a load-bearing area is likely to
cause the vehicle to fail. In this case
professional repairs are likely to be needed.
MDamage or corrosion which causes sharp
or otherwise dangerous edges to be exposed
will also cause the vehicle to fail.
Petrol models
MHave the engine at normal operating
temperature, and make sure that it is in good
tune (ignition system in good order, air filter
element clean, etc).
MBefore any measurements are carried out,
raise the engine speed to around 2500 rpm,
and hold it at this speed for 20 seconds. Allowthe engine speed to return to idle, and watch
for smoke emissions from the exhaust
tailpipe. If the idle speed is obviously much
too high, or if dense blue or clearly-visible
black smoke comes from the tailpipe for more
than 5 seconds, the vehicle will fail. As a rule
of thumb, blue smoke signifies oil being burnt
(engine wear) while black smoke signifies
unburnt fuel (dirty air cleaner element, or other
carburettor or fuel system fault).
MAn exhaust gas analyser capable of
measuring carbon monoxide (CO) and
hydrocarbons (HC) is now needed. If such an
instrument cannot be hired or borrowed, a
local garage may agree to perform the check
for a small fee.
CO emissions (mixture)
MAt the time of writing, the maximum CO
level at idle is 3.5% for vehicles first used after
August 1986 and 4.5% for older vehicles.
From January 1996 a much tighter limit
(around 0.5%) applies to catalyst-equipped
vehicles first used from August 1992. If the
CO level cannot be reduced far enough to
pass the test (and the fuel and ignition
systems are otherwise in good condition) then
the carburettor is badly worn, or there is some
problem in the fuel injection system or
catalytic converter (as applicable).
HC emissionsMWith the CO emissions within limits, HC
emissions must be no more than 1200 ppm
(parts per million). If the vehicle fails this test
at idle, it can be re-tested at around 2000 rpm;
if the HC level is then 1200 ppm or less, this
counts as a pass.
MExcessive HC emissions can be caused by
oil being burnt, but they are more likely to be
due to unburnt fuel.
Diesel models
MThe only emission test applicable to Diesel
engines is the measuring of exhaust smoke
density. The test involves accelerating the
engine several times to its maximum
unloaded speed.
Note: It is of the utmost importance that the
engine timing belt is in good condition before
the test is carried out.
M
Excessive smoke can be caused by a dirty
air cleaner element. Otherwise, professional
advice may be needed to find the cause.
4Checks carried out on
YOUR VEHICLE’S EXHAUST
EMISSION SYSTEM
REF

Engine
m mEngine fails to rotate when attempting to start
m mEngine rotates, but will not start
m mEngine difficult to start when cold
m mEngine difficult to start when hot
m mStarter motor noisy or excessively rough in engagement
m mEngine starts, but stops immediately
m mEngine idles erratically
m mEngine misfires at idle speed
m mEngine misfires throughout the driving speed range
m mEngine hesitates on acceleration
m mEngine stalls
m mEngine lacks power
m mEngine backfires
m mOil pressure warning light illuminated with engine running
m mEngine runs-on after switching off
m mEngine noises
Cooling system
m
mOverheating
m mOvercooling
m mExternal coolant leakage
m mInternal coolant leakage
m mCorrosion
Fuel and exhaust systems
m
mExcessive fuel consumption
m mFuel leakage and/or fuel odour
m mExcessive noise or fumes from exhaust system
Clutch
m
mPedal travels to floor - no pressure or very little resistance
m mClutch fails to disengage (unable to select gears)
m mClutch slips (engine speed increases, with no increase in vehicle
speed)
m mJudder as clutch is engaged
m mNoise when depressing or releasing clutch pedal
Manual transmission
m
mNoisy in neutral with engine running
m mNoisy in one particular gear
m mDifficulty engaging gears
m mJumps out of gear
m mVibration
m mLubricant leaks
Automatic transmission
m
mFluid leakage
m mTransmission fluid brown, or has burned smell
m mGeneral gear selection problems
m mTransmission will not downshift (kickdown) with accelerator fully
depressed
m mEngine will not start in any gear, or starts in gears other than Park
or Neutral
m mTransmission slips, shifts roughly, is noisy, or has no drive in
forward or reverse gears
Driveshafts
m mClicking or knocking noise on turns (at slow speed on full-lock)
m mVibration when accelerating or decelerating
Braking system
m
mVehicle pulls to one side under braking
m mNoise (grinding or high-pitched squeal) when brakes applied
m mExcessive brake pedal travel
m mBrake pedal feels spongy when depressed
m mExcessive brake pedal effort required to stop vehicle
m mJudder felt through brake pedal or steering wheel when braking
m mBrakes binding
m mRear wheels locking under normal braking
Suspension and steering systems
m
mVehicle pulls to one side
m mWheel wobble and vibration
m mExcessive pitching and/or rolling around corners, or during
braking
m mWandering or general instability
m mExcessively stiff steering
m mExcessive play in steering
m mLack of power assistance
m mTyre wear excessive
Electrical system
m
mBattery will not hold a charge for more than a few days
m mIgnition/no-charge warning light remains illuminated with engine
running
m mIgnition/no-charge warning light fails to come on
m mLights inoperative
m mInstrument readings inaccurate or erratic
m mHorn inoperative, or unsatisfactory in operation
m mWindscreen/tailgate wipers inoperative, or unsatisfactory in
operation
m mWindscreen/tailgate washers inoperative, or unsatisfactory in
operation
m mElectric windows inoperative, or unsatisfactory in operation
m mCentral locking system inoperative, or unsatisfactory in operation
The vehicle owner who does his or her own maintenance according to
the recommended service schedules should not have to use this section
of the manual very often. Modern component reliability is such that,
provided those items subject to wear or deterioration are inspected or
renewed at the specified intervals, sudden failure is comparatively rare.
Faults do not usually just happen as a result of sudden failure, but
develop over a period of time. Major mechanical failures in particular are
usually preceded by characteristic symptoms over hundreds or even
thousands of miles. Those components that do occasionally fail without
warning are often small and easily carried in the vehicle.
With any fault-finding, the first step is to decide where to begininvestigations. Sometimes this is obvious, but on other occasions, a
little detective work will be necessary. The owner who makes half a
dozen haphazard adjustments or replacements may be successful in
curing a fault (or its symptoms). However, will be none the wiser if the
fault recurs, and ultimately may have spent more time and money than
was necessary. A calm and logical approach will be found to be more
satisfactory in the long run. Always take into account any warning
signs or abnormalities that may have been noticed in the period
preceding the fault - power loss, high or low gauge readings, unusual
smells, etc. - and remember that failure of components such as fuses
or spark plugs may only be pointers to some underlying fault.
REF•12Fault Finding
Introduction

The pages that follow provide an easy-reference guide to the more
common problems that may occur during the operation of the vehicle.
These problems and their possible causes are grouped under headings
denoting various components or systems, such as Engine, Cooling
system, etc. The Chapter and/or Section that deals with the problem is
also shown in brackets. Whatever the fault, certain basic principles
apply. These are as follows:
Verify the fault. This is simply a matter of being sure that you know
what the symptoms are before starting work. This is particularly
important if you are investigating a fault for someone else, who may
not have described it very accurately.
Do not overlook the obvious. For example, if the vehicle will not start,
is there petrol in the tank? (Do not take anyone else’s word on this
particular point, and do not trust the fuel gauge either!) If an electrical
fault is indicated, look for loose or broken wires before digging out the
test gear.Cure the disease, not the symptom. Substituting a flat battery with a
fully charged one will get you off the hard shoulder, but if the
underlying cause is not attended to, the new battery will go the same
way. Similarly, changing oil-fouled spark plugs for a new set will get
you moving again, but remember that the reason for the fouling (if it
was not simply an incorrect grade of plug) will have to be established
and corrected.
Do not take anything for granted. Particularly, do not forget that a
“new” component may itself be defective (especially if it’s been rattling
around in the boot for months). Also do not leave components out of a
fault diagnosis sequence just because they are new or recently fitted.
When you do finally diagnose a difficult fault, you will probably realise
that all the evidence was there from the start.
Engine fails to rotate when attempting to start
MBattery terminal connections loose or corroded (Chapter 1).
MBattery discharged or faulty (Chapter 5).
MBroken, loose or disconnected wiring in the starting circuit
(Chapter 5).
MDefective starter solenoid or switch (Chapter 5).
MDefective starter motor (Chapter 5).
MStarter pinion or flywheel ring gear teeth loose or broken
(Chapters 2A and 5).
MEngine earth strap broken or disconnected (Chapter 5).
Engine rotates, but will not start
MFuel tank empty.
MBattery discharged (engine rotates slowly), (Chapter 5).
MBattery terminal connections loose or corroded (Chapter 1).
MIgnition components damp or damaged (Chapters 1 and 5).
MBroken, loose or disconnected wiring in the ignition circuit
(Chapters 1 and 5).
MWorn, faulty or incorrectly gapped spark plugs (Chapter 1).
MChoke mechanism incorrectly adjusted, worn or sticking -
carburettor models (Chapter 4A).
MFaulty fuel cut-off solenoid - carburettor models (Chapter 4A).
MFuel injection system fault - fuel-injected models (Chapter 4B).
MMajor mechanical failure (e.g. camshaft drive), (Chapter 2A or 2B).
Engine difficult to start when cold
MBattery discharged (Chapter 5).
MBattery terminal connections loose or corroded (Chapter 1).
MWorn, faulty or incorrectly gapped spark plugs (Chapter 1).
MChoke mechanism incorrectly adjusted, worn or sticking -
carburettor models (Chapter 4A).
MFuel injection system fault - fuel-injected models (Chapter 4B).
MOther ignition system fault (Chapters 1 and 5).
MLow cylinder compressions (Chapter 2A).
Engine difficult to start when hot
MAir filter element dirty or clogged (Chapter 1).
MChoke mechanism incorrectly adjusted, worn or sticking -
carburettor models (Chapter 4A).
MFuel injection system fault - fuel-injected models (Chapter 4B).
MLow cylinder compressions (Chapter 2A).
Starter motor noisy or excessively rough in
engagement
MStarter pinion or flywheel ring gear teeth loose or broken
(Chapters 2A and 5).
MStarter motor mounting bolts loose or missing (Chapter 5).
MStarter motor internal components worn or damaged (Chapter 5).
Engine starts, but stops immediately
MLoose or faulty electrical connections in the ignition circuit
(Chapters 1 and 5B).
MVacuum leak at the carburettor/throttle body or inlet manifold
(Chapter 4A or 4B).
MBlocked carburettor jet(s) or internal passages - carburettor
models (Chapter 4A).
MBlocked injector/fuel injection system fault - fuel-injected models
(Chapter 4B).
Engine idles erratically
MAir filter element clogged (Chapter 1).
MVacuum leak at the carburettor/throttle body, inlet manifold or
associated hoses (Chapter 4A or 4B).
MWorn, faulty or incorrectly gapped spark plugs (Chapter 1).
MUneven or low cylinder compressions (Chapter 2A).
MCamshaft lobes worn (Chapter 2A or 2B).
MTiming belt incorrectly tensioned (Chapter 2A or 2B).
MBlocked carburettor jet(s) or internal passages - carburettor
models (Chapter 4A).
MBlocked injector/fuel injection system fault - fuel-injected models
(Chapter 4B).
Engine misfires at idle speed
MWorn, faulty or incorrectly gapped spark plugs (Chapter 1).
MFaulty spark plug HT leads (Chapter 1).
MVacuum leak at the carburettor/throttle body, inlet manifold or
associated hoses (Chapter 4A or 4B).
MBlocked carburettor jet(s) or internal passages - carburettor
models (Chapter 4A).
MBlocked injector/fuel injection system fault - fuel-injected models
(Chapter 4B).
MDistributor cap cracked or tracking internally (where applicable),
(Chapter 1).
MUneven or low cylinder compressions (Chapter 2A).
MDisconnected, leaking, or perished crankcase ventilation hoses
(Chapter 4C).
Engine misfires throughout the driving speed
range
MFuel filter choked (Chapter 1).
MFuel pump faulty, or delivery pressure low (Chapter 4A or 4B).
MFuel tank vent blocked, or fuel pipes restricted (Chapter 4A or 4B).
MVacuum leak at the carburettor/throttle body, inlet manifold or
associated hoses (Chapter 4A or 4B).
MWorn, faulty or incorrectly gapped spark plugs (Chapter 1).
MFaulty spark plug HT leads (Chapter 1).
MDistributor cap cracked or tracking internally (where applicable),
(Chapter 1).
Fault Finding REF•13
REF
Engine

MFaulty ignition coil (Chapter 5).
MUneven or low cylinder compressions (Chapter 2A).
MBlocked carburettor jet(s) or internal passages - carburettor
models (Chapter 4A).
MBlocked injector/fuel injection system fault - fuel-injected models
(Chapter 4B).
Engine hesitates on acceleration
MWorn, faulty or incorrectly gapped spark plugs (Chapter 1).
MVacuum leak at the carburettor/throttle body, inlet manifold or
associated hoses (Chapter 4A or 4B).
MBlocked carburettor jet(s) or internal passages - carburettor
models (Chapter 4A).
MBlocked injector/fuel injection system fault - fuel-injected models
(Chapter 4B).
Engine stalls
MVacuum leak at the carburettor/throttle body, inlet manifold or
associated hoses (Chapter 4A or 4B).
MFuel filter choked (Chapter 1).
MFuel pump faulty, or delivery pressure low (Chapter 4A or 4B).
MFuel tank vent blocked, or fuel pipes restricted (Chapter 4A or 4B).
MBlocked carburettor jet(s) or internal passages - carburettor
models (Chapter 4A).
MBlocked injector/fuel injection system fault - fuel-injected models
(Chapter 4B).
Engine lacks power
MTiming belt incorrectly fitted or tensioned (Chapter 2A or 2B).
MFuel filter choked (Chapter 1).
MFuel pump faulty, or delivery pressure low (Chapter 4A or 4B).
MUneven or low cylinder compressions (Chapter 2A).
MWorn, faulty or incorrectly gapped spark plugs (Chapter 1).
MVacuum leak at the carburettor/throttle body, inlet manifold or
associated hoses (Chapter 4A or 4B).
MBlocked carburettor jet(s) or internal passages - carburettor
models (Chapter 4A).
MBlocked injector/fuel injection system fault - fuel-injected models
(Chapter 4B).
MBrakes binding (Chapters 1 and 9).
MClutch slipping (Chapter 6).
Engine backfires
MTiming belt incorrectly fitted or tensioned (Chapter 2A or 2B).
MVacuum leak at the carburettor/throttle body, inlet manifold or
associated hoses (Chapter 4A or 4B).
MBlocked carburettor jet(s) or internal passages - carburettor
models (Chapter 4A).
MBlocked injector/fuel injection system fault - fuel-injected models
(Chapter 4B).
Oil pressure warning light illuminated with engine
running
MLow oil level, or incorrect oil grade (Chapter 1).
MFaulty oil pressure warning light switch (Chapter 12).
MWorn engine bearings and/or oil pump (Chapter 2A).
MHigh engine operating temperature (Chapter 3).
MOil pressure relief valve defective (Chapter 2A).
MOil pick-up strainer clogged (Chapter 2A).
Engine runs-on after switching off
MExcessive carbon build-up in engine (Chapter 2A).
MHigh engine operating temperature (Chapter 3).
MFaulty fuel cut-off solenoid - carburettor models (Chapter 4A).
MFuel injection system fault - fuel-injected models (Chapter 4B).
Engine noises
Pre-ignition (pinking) or knocking during acceleration or
under load
MIgnition timing incorrect/ignition system fault (Chapters 1 and 5).
MIncorrect grade of spark plug (Chapter 1).
MIncorrect grade of fuel (Chapter 1).
MVacuum leak at the carburettor/throttle body, inlet manifold or
associated hoses (Chapter 4A or 4B).
MExcessive carbon build-up in engine (Chapter 2A).
MBlocked carburettor jet(s) or internal passages - carburettor
models (Chapter 4A).
MBlocked injector/fuel injection system fault - fuel-injected models
(Chapter 4B).
Whistling or wheezing noises
MLeaking inlet manifold or carburettor/throttle body gasket
(Chapter 4A or 4B).
MLeaking exhaust manifold gasket or pipe-to-manifold joint
(Chapter 4C).
MLeaking vacuum hose (Chapters 4A, 4B, 4C, 5, 9 and 12).
MBlowing cylinder head gasket (Chapter 2A or 2B).
Tapping or rattling noises
MWorn valve gear or camshaft (Chapter 2A or 2B).
MAncillary component fault (coolant pump, alternator, etc.)
(Chapters 3, 5, etc.).
Knocking or thumping noises
MWorn big-end bearings (regular heavy knocking, perhaps less
under load), (Chapter 2A or 2B).
MWorn main bearings (rumbling and knocking, perhaps worsening
under load), (Chapter 2A or 2B).
MPiston slap (most noticeable when cold), (Chapter 2A).
MAncillary component fault (coolant pump, alternator, etc.)
(Chapters 3, 5, etc.).
REF•14Fault Finding
Engine (continued)

Glossary of Technical Terms REF•21
REF
CamshaftA 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.
CanisterA container in an evaporative
emission control system; contains activated
charcoal granules to trap vapours from the
fuel system.
CarburettorA device which mixes fuel with
air in the proper proportions to provide a
desired power output from a spark ignition
internal combustion engine.
CastellatedResembling the parapets along
the top of a castle wall. For example, a
castellated balljoint stud nut.
CastorIn 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 converterA silencer-like device in
the exhaust system which converts certain
pollutants in the exhaust gases into less
harmful substances.
CirclipA 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.
ClearanceThe amount of space between
two parts. For example, between a piston and
a cylinder, between a bearing and a journal,
etc.
Coil springA 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.
CompressionReduction in volume, and
increase in pressure and temperature, of a
gas, caused by squeezing it into a smaller
space.
Compression ratioThe relationship between
cylinder volume when the piston is at top
dead centre and cylinder volume when the
piston is at bottom dead centre.
Constant velocity (CV) jointA type of
universal joint that cancels out vibrations
caused by driving power being transmitted
through an angle.
Core plugA 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.
CrankcaseThe lower part of the engine
block in which the crankshaft rotates.
CrankshaftThe main rotating member, or
shaft, running the length of the crankcase,
with offset “throws” to which the connecting
rods are attached.Crocodile clipSee Alligator clip
DDiagnostic codeCode numbers obtained by
accessing the diagnostic mode of an engine
management computer. This code can be
used to determine the area in the system
where a malfunction may be located.
Disc brakeA brake design incorporating a
rotating disc onto which brake pads are
squeezed. The resulting friction converts the
energy of a moving vehicle into heat.
Double-overhead cam (DOHC)An engine
that uses two overhead camshafts, usually
one for the intake valves and one for the
exhaust valves.
Drivebelt(s)The belt(s) used to drive
accessories such as the alternator, water
pump, power steering pump, air conditioning
compressor, etc. off the crankshaft pulley.
DriveshaftAny shaft used to transmit
motion. Commonly used when referring to the
axleshafts on a front wheel drive vehicle.
Drum brakeA type of brake using a drum-
shaped metal cylinder attached to the inner
surface of the wheel. When the brake pedal is
pressed, curved brake shoes with friction
linings press against the inside of the drum to
slow or stop the vehicle.
Castellated nut
Catalytic converter
Crankshaft assembly
Carburettor
Canister
Drum brake assembly
Accessory drivebelts
Driveshaft

REF•22Glossary of Technical Terms
EEGR valveA valve used to introduce exhaust
gases into the intake air stream.
Electronic control unit (ECU)A computer
which controls (for instance) ignition and fuel
injection systems, or an anti-lock braking
system. For more information refer to the
Haynes Automotive Electrical and Electronic
Systems Manual.
Electronic Fuel Injection (EFI)A computer
controlled fuel system that distributes fuel
through an injector located in each intake port
of the engine.
Emergency brakeA braking system,
independent of the main hydraulic system,
that can be used to slow or stop the vehicle if
the primary brakes fail, or to hold the vehicle
stationary even though the brake pedal isn’t
depressed. It usually consists of a hand lever
that actuates either front or rear brakes
mechanically through a series of cables and
linkages. Also known as a handbrake or
parking brake.
EndfloatThe amount of lengthwise
movement between two parts. As applied to a
crankshaft, the distance that the crankshaft
can move forward and back in the cylinder
block.
Engine management system (EMS)A
computer controlled system which manages
the fuel injection and the ignition systems in
an integrated fashion.
Exhaust manifoldA part with several
passages through which exhaust gases leave
the engine combustion chambers and enter
the exhaust pipe.
FFan clutchA viscous (fluid) drive coupling
device which permits variable engine fan
speeds in relation to engine speeds.Feeler bladeA thin strip or blade of hardened
steel, ground to an exact thickness, used to
check or measure clearances between parts.
Firing orderThe order in which the engine
cylinders fire, or deliver their power strokes,
beginning with the number one cylinder.
Flywheel A heavy spinning wheel in which
energy is absorbed and stored by means of
momentum. On cars, the flywheel is attached
to the crankshaft to smooth out firing
impulses.
Free playThe amount of travel before any
action takes place. The “looseness” in a
linkage, or an assembly of parts, between the
initial application of force and actual
movement. For example, the distance the
brake pedal moves before the pistons in the
master cylinder are actuated.
FuseAn electrical device which protects a
circuit against accidental overload. The typical
fuse contains a soft piece of metal which is
calibrated to melt at a predetermined current
flow (expressed as amps) and break the
circuit.
Fusible linkA circuit protection device
consisting of a conductor surrounded by
heat-resistant insulation. The conductor is
smaller than the wire it protects, so it acts as
the weakest link in the circuit. Unlike a blown
fuse, a failed fusible link must frequently be
cut from the wire for replacement.
GGapThe distance the spark must travel in
jumping from the centre electrode to the sideelectrode in a spark plug. Also refers to the
spacing between the points in a contact
breaker assembly in a conventional points-
type ignition, or to the distance between the
reluctor or rotor and the pickup coil in an
electronic ignition.
GasketAny thin, soft material - usually cork,
cardboard, asbestos or soft metal - installed
between two metal surfaces to ensure a good
seal. For instance, the cylinder head gasket
seals the joint between the block and the
cylinder head.
GaugeAn instrument panel display used to
monitor engine conditions. A gauge with a
movable pointer on a dial or a fixed scale is an
analogue gauge. A gauge with a numerical
readout is called a digital gauge.
HHalfshaftA rotating shaft that transmits
power from the final drive unit to a drive
wheel, usually when referring to a live rear
axle.
Harmonic balancerA device designed to
reduce torsion or twisting vibration in the
crankshaft. May be incorporated in the
crankshaft pulley. Also known as a vibration
damper.
HoneAn abrasive tool for correcting small
irregularities or differences in diameter in an
engine cylinder, brake cylinder, etc.
Hydraulic tappetA tappet that utilises
hydraulic pressure from the engine’s
lubrication system to maintain zero clearance
(constant contact with both camshaft and
valve stem). Automatically adjusts to variation
in valve stem length. Hydraulic tappets also
reduce valve noise.
IIgnition timingThe moment at which the
spark plug fires, usually expressed in the
number of crankshaft degrees before the
piston reaches the top of its stroke.
Inlet manifoldA tube or housing with
passages through which flows the air-fuel
mixture (carburettor vehicles and vehicles with
throttle body injection) or air only (port fuel-
injected vehicles) to the port openings in the
cylinder head.
Exhaust manifold
Feeler blade
Adjusting spark plug gap
Gasket
EGR valve

Glossary of Technical Terms REF•23
JJump startStarting the engine of a vehicle
with a discharged or weak battery by
attaching jump leads from the weak battery to
a charged or helper battery.
LLoad Sensing Proportioning Valve (LSPV)A
brake hydraulic system control valve that
works like a proportioning valve, but also
takes into consideration the amount of weight
carried by the rear axle.
LocknutA nut used to lock an adjustment
nut, or other threaded component, in place.
For example, a locknut is employed to keep
the adjusting nut on the rocker arm in
position.
LockwasherA form of washer designed to
prevent an attaching nut from working loose.
MMacPherson strutA type of front
suspension system devised by Earle
MacPherson at Ford of England. In its original
form, a simple lateral link with the anti-roll bar
creates the lower control arm. A long strut - an
integral coil spring and shock absorber - is
mounted between the body and the steering
knuckle. Many modern so-called MacPherson
strut systems use a conventional lower A-arm
and don’t rely on the anti-roll bar for location.
MultimeterAn electrical test instrument with
the capability to measure voltage, current and
resistance.
NNOxOxides of Nitrogen. A common toxic
pollutant emitted by petrol and diesel engines
at higher temperatures.
OOhmThe unit of electrical resistance. One
volt applied to a resistance of one ohm will
produce a current of one amp.
OhmmeterAn instrument for measuring
electrical resistance.
O-ringA type of sealing ring made of a
special rubber-like material; in use, the O-ring
is compressed into a groove to provide the
sealing action.Overhead cam (ohc) engineAn engine with
the camshaft(s) located on top of the cylinder
head(s).
Overhead valve (ohv) engineAn engine with
the valves located in the cylinder head, but
with the camshaft located in the engine block.
Oxygen sensorA device installed in the
engine exhaust manifold, which senses the
oxygen content in the exhaust and converts
this information into an electric current. Also
called a Lambda sensor.
PPhillips screwA type of screw head having a
cross instead of a slot for a corresponding
type of screwdriver.
PlastigageA thin strip of plastic thread,
available in different sizes, used for measuring
clearances. For example, a strip of Plastigage
is laid across a bearing journal. The parts are
assembled and dismantled; the width of the
crushed strip indicates the clearance between
journal and bearing.
Propeller shaftThe long hollow tube with
universal joints at both ends that carries
power from the transmission to the differential
on front-engined rear wheel drive vehicles.
Proportioning valveA hydraulic control
valve which limits the amount of pressure to
the rear brakes during panic stops to prevent
wheel lock-up.
RRack-and-pinion steeringA steering system
with a pinion gear on the end of the steering
shaft that mates with a rack (think of a geared
wheel opened up and laid flat). When the
steering wheel is turned, the pinion turns,
moving the rack to the left or right. This
movement is transmitted through the track
rods to the steering arms at the wheels.
RadiatorA liquid-to-air heat transfer device
designed to reduce the temperature of the
coolant in an internal combustion engine
cooling system.
RefrigerantAny substance used as a heat
transfer agent in an air-conditioning system.
R-12 has been the principle refrigerant for
many years; recently, however, manufacturers
have begun using R-134a, a non-CFC
substance that is considered less harmful tothe ozone in the upper atmosphere.
Rocker armA lever arm that rocks on a shaft
or pivots on a stud. In an overhead valve
engine, the rocker arm converts the upward
movement of the pushrod into a downward
movement to open a valve.
RotorIn a distributor, the rotating device
inside the cap that connects the centre
electrode and the outer terminals as it turns,
distributing the high voltage from the coil
secondary winding to the proper spark plug.
Also, that part of an alternator which rotates
inside the stator. Also, the rotating assembly
of a turbocharger, including the compressor
wheel, shaft and turbine wheel.
RunoutThe amount of wobble (in-and-out
movement) of a gear or wheel as it’s rotated.
The amount a shaft rotates “out-of-true.” The
out-of-round condition of a rotating part.
SSealantA liquid or paste used to prevent
leakage at a joint. Sometimes used in
conjunction with a gasket.
Sealed beam lampAn older headlight design
which integrates the reflector, lens and
filaments into a hermetically-sealed one-piece
unit. When a filament burns out or the lens
cracks, the entire unit is simply replaced.
Serpentine drivebeltA single, long, wide
accessory drivebelt that’s used on some
newer vehicles to drive all the accessories,
instead of a series of smaller, shorter belts.
Serpentine drivebelts are usually tensioned by
an automatic tensioner.
ShimThin spacer, commonly used to adjust
the clearance or relative positions between
two parts. For example, shims inserted into or
under bucket tappets control valve
clearances. Clearance is adjusted by
changing the thickness of the shim.
Slide hammerA special puller that screws
into or hooks onto a component such as a
shaft or bearing; a heavy sliding handle on the
shaft bottoms against the end of the shaft to
knock the component free.
SprocketA tooth or projection on the
periphery of a wheel, shaped to engage with a
chain or drivebelt. Commonly used to refer to
the sprocket wheel itself.
Starter inhibitor switchOn vehicles with an
O-ring
Serpentine drivebelt
Plastigage
REF