1988 OPEL CALIBRA radiator

level in the expansion tank, and top-up if
necessary. Note that the system must be cold
before an accurate level is indicated in the
expansion tank. If the expansion tank cap is
removed while the engine is still warm, cover
the cap with a thick cloth and unscrew the
cap slowly, to gradually relieve the system
pressure. Take care to avoid scalding by
steam or coolant escaping from the
pressurised system.
9On DOHC models, refit the engine
undershield on completion.
5Coolant mixture -general
1It is important to use an antifreeze mixture
in the cooling system all year round, to
prevent corrosion of the alloy engine
components. The coolant mixture should be
made up from clean, preferably soft, tap
water, and a good quality antifreeze
containing corrosion inhibitor. Ensure that the
antifreeze is ethylene glycol based, as the
cheaper methanol based types evaporate
over a period of time.
2The proportions of water and antifreeze
used will depend on the degree of protection
required. A coolant mixture containing 25%
antifreeze should be regarded as the
minimum strength required to maintain good
anti-corrosion properties. Details of the
degree of protection provided against freezing
will be supplied with the antifreeze by the
manufacturers. For absolute protection, use a
50% antifreeze mixture.
3The coolant mixture should be renewed
every two years, as the corrosion inhibitors
will deteriorate with time.
4Before filling the system with fresh coolant,
drain and flush the system, as described in
Sections 2 and 3, and check that all hoses are
secure and that the clips are tight. Antifreeze
has a searching action, and will leak morerapidly than plain water.
5Refill the system as described in Section 4.
All future topping-up should be carried out
using a coolant mixture of the same
proportions as that used to initially fill the
system.
6Do not use antifreeze in the windscreen
wash system, as it will attack the vehicle
paintwork. Note that antifreeze is poisonous,
and must be handled with due care.
6Radiator (manual
transmission) -removal and
refitting
3
Removal
1The radiator can be removed complete with
the coolant fan and shroud if there is no need
to disturb the fan. If desired, the fan and its
shroud can be removed from the radiator,
with reference to Section 12.
2Drain the cooling system, as described in
Section 2.
3Disconnect the radiator top hose and the
expansion tank at the radiator.
4Disconnect the battery negative lead, then
disconnect the wiring from the cooling fan
switch, located at the bottom right-hand side
of the radiator.5Disconnect the cooling fan wiring
connector, noting its location for use when
refitting.
6Compress and remove the two radiator
securing clips, located at the top corners of
the radiator (see illustration).
7Pull the top of the radiator back towards the
engine to free it from the top mountings, then
lift the radiator to disengage the lower
securing lugs. Move the radiator clear of the
vehicle, taking care not to damage the cooling
fins (see illustrations).
Refitting
8The radiator can be inspected and cleaned
as described in Section 8.
9Refitting is a reversal of removal, bearing in
mind the following points.
10Ensure that the radiator rubber mountings
are in good condition and renew if necessary,
and ensure that the lower securing lugs
engage correctly as the radiator is refitted.
11Refill the cooling system, (Section 4).
7Radiator (automatic
transmission) -removal and
refitting
3
Removal
1On models with automatic transmission,
the radiator left-hand side tank incorporates a
heat exchanger to cool the transmission fluid.
It is connected to the transmission by a pair of
flexible hoses, with a metal pipe at each end.
2When removing the radiator, either clamp
the transmission fluid cooler flexible hoses, or
slacken their clamps, work them off their
unions and swiftly plug or cap each hose end
and union to minimise the loss of fluid and to
prevent the entry of dirt.
Refitting
3On refitting, reverse the removal procedure
and do not forget to check the transmission
fluid level, topping-up as necessary to replace
the lost fluid, as described in Chapter 7B.
Cooling, heating and ventilation systems 3•3
6.7B Withdrawing the radiator -
2.0 litre SOHC model6.7A Radiator freed from top right-hand mounting -
1.6 litre model
6.6 Compressing a radiator securing clip -
2.0 litre SOHC model
3

8Radiator -inspection and
cleaning
2
1If the radiator has been removed due to
suspected blockage, reverse-flush it as
described in Section 3.
2Clean dirt and debris from the radiator fins,
using an air jet or a soft brush. Take care, as
the fins are easily damaged and are sharp.
3If necessary, a radiator specialist can
perform a “flow test” on the radiator, to
establish whether an internal blockage exists.
4A leaking radiator must be referred to a
specialist for permanent repair. Do not
attempt to weld or solder a leaking radiator,
as damage to the plastic components may
result.
5In an emergency, minor leaks from the
radiator can be cured by using a radiator
sealant.
9Thermostat - removal and
refitting
3
Note: A new O-ring should be used when
refitting the thermostat
1.4 and 1.6 litre models (except
C16 NZ2)
Removal
1Partially drain the cooling system, as
described in Section 2.
2Remove the timing belt and the camshaft
sprocket, as described in Chapters 2A or 2B,
(as applicable).
3Unscrew and remove the two upper bolts
securing the rear timing belt cover to the
cylinder head, and the lower right-hand bolt
securing the cover to the cylinder block.
4Disconnect the coolant hose from the
thermostat housing.
5Pull the rear timing belt cover forwards,
away from the cylinder head, for access to the
two thermostat housing securing bolts.
6Unscrew and remove the two thermostat
housing securing bolts, and lift off the
thermostat housing (see illustration).7Withdraw the thermostat from the cylinder
head, noting that coolant may be released
from the radiator bottom outlet as the
thermostat is withdrawn, even though the
cooling system has been partially drained
(see illustration).
8Remove the sealing ring from the edge of
the thermostat.
9If desired, the thermostat can be tested, as
described in Section 10.
Refitting
10Refitting is a reversal of removal, using a
new sealing ring, and bearing in mind the
following points.
11Refit the camshaft sprocket and timing
belt, and tension the timing belt, as described
in Chapters 2A or 2B.
12Refill the cooling system, (Section 4).
C16 NZ2, 1.8 and 2.0 litre models
Removal
13Remove the engine undershield, if fitted.
Partially drain the cooling system, as
described in Section 2.
14Disconnect the radiator top hose from the
thermostat cover.
15Unscrew and remove the thermostat
cover securing bolts, and withdraw the cover
complete with thermostat. Recover the O-ring
(see illustrations).
16If desired, the thermostat can be tested,
as described in Section 10.
17Note that if it is necessary to renew the
thermostat, the complete cover and
thermostat must be renewed as an assembly,
as the two cannot be separated.
Refitting
18Refitting is a reversal of removal, but use a
new O-ring, and on completion refill the
cooling system, as described in Section 4.
10Thermostat -testing
2
1A rough test of the thermostat may be
made by suspending it with a piece of string in
a container full of water. Heat the water to
bring it to the boil -the thermostat must open
by the time the water boils. If not, renew it.
2If a thermometer is available, the precise
opening temperature of the thermostat may
be determined, and compared with the figures
given in the Specifications. The opening
temperature is also marked on the thermostat
(see illustration).
3A thermostat that fails to close as the water
cools must also be renewed.
11Coolant pump -removal and
refitting
4
SOHC models
Removal
1If the engine is in the vehicle, drain the
cooling system, as described in Section 2.
2On 1.4 and 1.6 litre models (except C16
NZ2), remove the rear timing belt cover. On
3•4Cooling, heating and ventilation systems
9.6 Remove the thermostat housing . . .9.15A Withdraw the thermostat cover
complete with thermostat . . .
10.2 View of thermostat showing opening
temperature markings - 1.6 litre model
9.15B . . .and recover the O-ring -
2.0 litre SOHC model
9.7 . . .and withdraw the thermostat -
1.6 litre model

C16 NZ2, 1.8 and 2.0 litre models, remove the
timing belt. Details are as described in
Chapter 2A.
3Remove timing belt tension roller from oil
pump, where applicable.
4Unscrew and remove the coolant pump
securing bolts (see illustration).
5Withdraw the coolant pump from the
cylinder block, and recover the O-ring (see
illustrations). It may be necessary to tap the
pump lightly with a plastic-faced hammer to
free it from the cylinder block.
6If desired, the rear timing belt cover can be
removed from the pump by rotating the cover
to release it from the flange on the pump.
7No overhaul of the coolant pump is
possible, and if faulty, the unit must be
renewed.
Refitting
8Refitting is a reversal of removal, bearing in
mind the following points.
9Use a new O-ring when refitting the pump.
Before refitting the pump, smear the pump
mounting face in the cylinder block and the O-
ring with a silicone grease or petroleum jelly.
10Do not fully tighten the pump securing
bolts until the timing belt has been fitted and
tensioned.
11Refit and tension the timing belt, as
described in Chapter 2A.
12If the engine is in the vehicle, refill the
cooling system, as described in Section 4.
DOHC models
Removal
13Remove the engine undershield.
14If the engine is in the vehicle, drain the
cooling system, as described in Section 2.
15Remove the timing belt, camshaft
sprockets, crankshaft sprocket, timing belt
tensioner and idler rollers, and the timing belt
rear cover, as described in Chapter 2B.
16Proceed as described in paragraphs 4
and 5.
17No overhaul of the coolant pump is
possible, and if faulty, the unit must be
renewed.
Refitting
18Refitting is a reversal of removal, bearing
in mind the following points.19Always use a new O-ring. Before fitting
the pump, smear the pump mating face in the
cylinder block and the O-ring with a silicone
grease or petroleum jelly.
20Refit the pump, and ensure that the lugs
on the pump and the cylinder block are
aligned before tightening the pump securing
bolts (see illustration).
21Refit the remaining components, and
tension the timing belt, as described in
Chapter 2B.
22If the engine is in the vehicle, refill the
cooling system, as described in Section 4.
Replace the undershield.
12Cooling fan - removal and
refitting
3
Removal
1Disconnect the battery negative lead.
2Disconnect the wiring from the cooling fan,
noting the location of the wiring connector for
use when refitting.
3Unscrew the two upper fan shroud securing
bolts from the top corners of the shroud, then
tilt the assembly back slightly towards the
engine, and withdraw it upwards away from
the radiator (see illustration).
4To separate the fan motor from the shroud,
unscrew the three securing nuts. If desired,
the fan blades can be separated from the
motor by removing the securing spring clip
from the end of the motor shaft.5No spare parts are available for the motor,
and if the unit is faulty, it must be renewed.
Refitting
6Reassembly (where applicable), and
refitting are reversals of the dismantling and
removal procedures, but ensure that the lower
end of the fan shroud locates correctly on the
radiator.
7On completion, start the engine and run it
until it reaches normal operating temperature,
then continue to run the engine and check
that the cooling fan cuts in and functions
correctly.
13Expansion tank and coolant
level sensor -removal and
refitting
3
Expansion tank
Removal
1The expansion tank is secured by a single
screw at its front edge. If the tank is to be
moved for access purposes, it should be
possible to move it sufficiently within the
confines of the hoses once the securing
screw has been removed. If the tank is to be
removed completely, continue as follows.
2Disconnect the two hoses from the top of
the expansion tank, and suspend them above
the height of the engine to prevent coolant loss.
3Remove the tank securing screw, then
manipulate the tank from its location, holding
it as high as possible above the engine.
Cooling, heating and ventilation systems 3•5
11.5B . . .and recover the O-ring -
2.0 litre SOHC model
12.3 Withdrawing the fan shroud assembly
- 2.0 litre SOHC model11.20 Lugs (arrowed) on coolant pump
and cylinder block must be aligned -
DOHC models
11.5A Withdraw the coolant pump . . .11.4 Coolant pump securing bolt
(arrowed) - 2.0 litre SOHC model
3

4Position a container beneath the tank, then
disconnect the bottom hose and allow the
contents of the tank to drain into the
container. Suspend the bottom hose as high
as possible above the engine to prevent
coolant loss.
Refitting
5Refitting is a reversal of removal, but on
completion check and if necessary top-up the
coolant level, as described in Section 4. The
coolant drained from the expansion tank
during removal can be re-used, provided it
has not been contaminated.
Coolant level sensor
6The coolant level sensor, where fitted, is an
integral part of the expansion tank cap. If the
level sensor is faulty, the complete cap
assembly must be renewed.
14Temperature gauge sender -
removal and refitting
2
Removal
1The sender is screwed into the inlet
manifold on 1.4 and 1.6 litre models (except
C16 NZ2), and into the thermostat housing
on C16 NZ2, 1.8 and 2.0 litre models (see
illustrations).
2Partially drain the cooling system, as
described in Section 2, to minimise coolant
spillage.
3Disconnect the battery negative lead.4Disconnect the wiring from the switch, then
unscrew the switch from its location.
Refitting
5Refitting is a reversal of removal,
remembering the following points.
6Coat the sender threads with sealant before
fitting.
7Top-up the cooling system, as described in
Section 4.
8On completion, start the engine and check
the operation of the temperature gauge. Also
check for coolant leaks.
15Cooling fan switch -removal
and refitting
3
Note: A new sealing ring should be used
when refitting the switch
Removal
1The cooling fan switch is located at the
bottom right-hand corner of the radiator (see
illustration).
2If a faulty switch is suspected, the circuit to
the fan motor can be tested by temporarily
bridging the terminals in the switch wiring
plug, and switching on the ignition. If the
cooling fan now operates, the switch is faulty
and should be renewed. To remove the
switch, continue as follows.
3Disconnect the battery negative lead, then
disconnect the switch wiring plug if not
already done.4Drain the cooling system, as described in
Section 2.
5Unscrew the switch from the radiator and
recover the sealing ring.
Refitting
6Refitting is a reversal of removal, but use a
new sealing ring, and refill the cooling system
as described in Section 4.
7On completion, start the engine and run it
until it reaches normal operating temperature,
then continue to run the engine and check
that the cooling fan cuts in and functions
correctly.
16Heater control panel -
removal and refitting
3
Removal
1Disconnect the battery negative lead.
2Remove the passenger side footwell trim,
the steering column shrouds, and the
instrument panel lower and upper trim panels,
as described in Chapter 11.
3Remove the clock or trip computer, as
applicable, from the facia, referring to Chapter
12 if necessary.
4Remove the two heater control panel
securing screws from the clock/trip computer
aperture, and the remaining securing screw
from the right-hand end of the panel (exposed
by removing the instrument panel lower trim
panel), (see illustrations).
3•6Cooling, heating and ventilation systems
14.1A Disconnecting the wiring from the
temperature gauge sender - 1.6 litre model14.1C Temperature gauge sender location
(arrowed) - 2.0 litre DOHC model
16.4B . . . and the remaining screw from
the right-hand end of the panel16.4A Remove the two heater control
panel securing screws from the clock/trip
computer aperture . . .15.1 Cooling fan switch location -
2.0 litre SOHC model viewed from below
14.1B Temperature gauge sender location
(arrowed) - 2.0 litre SOHC model

Excessive fuel consumption
MAir filter element dirty or clogged (Chapter 1).
MChoke cable incorrectly adjusted, or choke sticking - carburettor
models (Chapter 4A).
MFuel injection system fault - fuel-injected models (Chapter 4B).
MIgnition timing incorrect/ignition system fault (Chapters 1 and 5).
MTyres under-inflated (Chapter 1).
Fuel leakage and/or fuel odour
MDamaged or corroded fuel tank, pipes or connections (Chapter 4A
or 4B).
MCarburettor float chamber flooding (float height incorrect) -
carburettor models (Chapter 4A).
Excessive noise or fumes from exhaust system
MLeaking exhaust system or manifold joints (Chapters 1 and 4C).
MLeaking, corroded or damaged silencers or pipe (Chapters 1 and 4C).
MBroken mountings causing body or suspension contact (Chapter 1).
Pedal travels to floor - no pressure or very little
resistance
MBroken clutch cable (Chapter 6).
MIncorrect clutch cable adjustment (Chapter 6).
MBroken clutch release bearing or fork (Chapter 6).
MBroken diaphragm spring in clutch pressure plate (Chapter 6).
Clutch fails to disengage (unable to select gears).
MIncorrect clutch cable adjustment (Chapter 6).
MClutch disc sticking on transmission input shaft splines (Chapter 6).
MClutch disc sticking to flywheel or pressure plate (Chapter 6).
MFaulty pressure plate assembly (Chapter 6).
MClutch release mechanism worn or incorrectly assembled (Chapter 6).
Clutch slips (engine speed increases, with no
increase in vehicle speed).
MIncorrect clutch cable adjustment (Chapter 6).
MClutch disc linings excessively worn (Chapter 6).MClutch disc linings contaminated with oil or grease (Chapter 6).
MFaulty pressure plate or weak diaphragm spring (Chapter 6).
Judder as clutch is engaged
MClutch disc linings contaminated with oil or grease (Chapter 6).
MClutch disc linings excessively worn (Chapter 6).
MClutch cable sticking or frayed (Chapter 6).
MFaulty or distorted pressure plate or diaphragm spring (Chapter 6).
MWorn or loose engine or transmission mountings (Chapter 2A or 2B).
MClutch disc hub or transmission input shaft splines worn (Chapter 6).
Noise when depressing or releasing clutch pedal
MWorn clutch release bearing (Chapter 6).
MWorn or dry clutch pedal bushes (Chapter 6).
MFaulty pressure plate assembly (Chapter 6).
MPressure plate diaphragm spring broken (Chapter 6).
MBroken clutch disc cushioning springs (Chapter 6).
Fault Finding REF•15
REF
Overheating
MInsufficient coolant in system (Chapter 1).
MThermostat faulty (Chapter 3).
MRadiator core blocked, or grille restricted (Chapter 3).
MElectric cooling fan or thermoswitch faulty (Chapter 3).
MPressure cap faulty (Chapter 3).
MIgnition timing incorrect/ignition system fault (Chapters 1 and 5).
MInaccurate temperature gauge sender unit (Chapter 3).
MAirlock in cooling system (Chapter 1).
Overcooling
MThermostat faulty (Chapter 3).
MInaccurate temperature gauge sender unit (Chapter 3).
External coolant leakage
MDeteriorated or damaged hoses or hose clips (Chapter 1).
MRadiator core or heater matrix leaking (Chapter 3).
MPressure cap faulty (Chapter 3).
MWater pump seal leaking (Chapter 3).
MBoiling due to overheating (Chapter 3).
MCore plug leaking (Chapter 2A).
Internal coolant leakage
MLeaking cylinder head gasket (Chapter 2A or 2B).
MCracked cylinder head or cylinder bore (Chapter 2A or 2B).
Corrosion
MInfrequent draining and flushing (Chapter 1).
MIncorrect coolant mixture or inappropriate coolant type (Chapter 1).
Cooling system
Clutch
Fuel and exhaust systems

REF•20Glossary of Technical Terms
A
ABS (Anti-lock brake system)A system,
usually electronically controlled, that senses
incipient wheel lockup during braking and
relieves hydraulic pressure at wheels that are
about to skid.
Air bag An inflatable bag hidden in the
steering wheel (driver’s side) or the dash or
glovebox (passenger side). In a head-on
collision, the bags inflate, preventing the
driver and front passenger from being thrown
forward into the steering wheel or windscreen.
Air cleanerA metal or plastic housing,
containing a filter element, which removes
dust and dirt from the air being drawn into the
engine.
Air filter elementThe actual filter in an air
cleaner system, usually manufactured from
pleated paper and requiring renewal at regular
intervals.
Allen keyA hexagonal wrench which fits into
a recessed hexagonal hole.
Alligator clipA long-nosed spring-loaded
metal clip with meshing teeth. Used to make
temporary electrical connections.
AlternatorA component in the electrical
system which converts mechanical energy
from a drivebelt into electrical energy to
charge the battery and to operate the starting
system, ignition system and electrical
accessories.
Ampere (amp)A unit of measurement for the
flow of electric current. One amp is the
amount of current produced by one volt
acting through a resistance of one ohm.
Anaerobic sealerA substance used to
prevent bolts and screws from loosening.
Anaerobic means that it does not require
oxygen for activation. The Loctite brand is
widely used.
AntifreezeA substance (usually ethylene
glycol) mixed with water, and added to a
vehicle’s cooling system, to prevent freezing
of the coolant in winter. Antifreeze also
contains chemicals to inhibit corrosion and
the formation of rust and other deposits thatwould tend to clog the radiator and coolant
passages and reduce cooling efficiency.
Anti-seize compoundA coating that
reduces the risk of seizing on fasteners that
are subjected to high temperatures, such as
exhaust manifold bolts and nuts.
AsbestosA natural fibrous mineral with great
heat resistance, commonly used in the
composition of brake friction materials.
Asbestos is a health hazard and the dust
created by brake systems should never be
inhaled or ingested.
AxleA shaft on which a wheel revolves, or
which revolves with a wheel. Also, a solid
beam that connects the two wheels at one
end of the vehicle. An axle which also
transmits power to the wheels is known as a
live axle.
AxleshaftA single rotating shaft, on either
side of the differential, which delivers power
from the final drive assembly to the drive
wheels. Also called a driveshaft or a halfshaft.
BBall bearingAn anti-friction bearing
consisting of a hardened inner and outer race
with hardened steel balls between two races.BearingThe curved surface on a shaft or in a
bore, or the part assembled into either, that
permits relative motion between them with
minimum wear and friction.
Big-end bearingThe bearing in the end of
the connecting rod that’s attached to the
crankshaft.
Bleed nippleA valve on a brake wheel
cylinder, caliper or other hydraulic component
that is opened to purge the hydraulic system
of air. Also called a bleed screw.
Brake bleedingProcedure for removing air
from lines of a hydraulic brake system.
Brake discThe component of a disc brake
that rotates with the wheels.
Brake drumThe component of a drum brake
that rotates with the wheels.
Brake liningsThe friction material which
contacts the brake disc or drum to retard the
vehicle’s speed. The linings are bonded or
riveted to the brake pads or shoes.
Brake padsThe replaceable friction pads
that pinch the brake disc when the brakes are
applied. Brake pads consist of a friction
material bonded or riveted to a rigid backing
plate.
Brake shoeThe crescent-shaped carrier to
which the brake linings are mounted and
which forces the lining against the rotating
drum during braking.
Braking systemsFor more information on
braking systems, consult the Haynes
Automotive Brake Manual.
Breaker barA long socket wrench handle
providing greater leverage.
BulkheadThe insulated partition between
the engine and the passenger compartment.
CCaliperThe non-rotating part of a disc-brake
assembly that straddles the disc and carries
the brake pads. The caliper also contains the
hydraulic components that cause the pads to
pinch the disc when the brakes are applied. A
caliper is also a measuring tool that can be set
to measure inside or outside dimensions of an
object.
Brake bleeding
Bearing
Axle assembly
Anti-seize compound
Alternator (exploded view)
Air filter

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

REF•24Glossary of Technical Terms
automatic transmission, a switch that
prevents starting if the vehicle is not in Neutral
or Park.
StrutSee MacPherson strut.
TTappetA cylindrical component which
transmits motion from the cam to the valve
stem, either directly or via a pushrod and
rocker arm. Also called a cam follower.
ThermostatA heat-controlled valve that
regulates the flow of coolant between the
cylinder block and the radiator, so maintaining
optimum engine operating temperature. A
thermostat is also used in some air cleaners in
which the temperature is regulated.
Thrust bearingThe bearing in the clutch
assembly that is moved in to the release levers
by clutch pedal action to disengage the
clutch. Also referred to as a release bearing.
Timing beltA toothed belt which drives the
camshaft. Serious engine damage may result
if it breaks in service.
Timing chainA chain which drives the
camshaft.
Toe-inThe amount the front wheels are
closer together at the front than at the rear. On
rear wheel drive vehicles, a slight amount of
toe-in is usually specified to keep the front
wheels running parallel on the road by
offsetting other forces that tend to spread the
wheels apart.
Toe-outThe amount the front wheels are
closer together at the rear than at the front. Onfront wheel drive vehicles, a slight amount of
toe-out is usually specified.
ToolsFor full information on choosing and
using tools, refer to the Haynes Automotive
Tools Manual.
TracerA stripe of a second colour applied to
a wire insulator to distinguish that wire from
another one with the same colour insulator.
Tune-upA process of accurate and careful
adjustments and parts replacement to obtain
the best possible engine performance.
TurbochargerA centrifugal device, driven by
exhaust gases, that pressurises the intake air.
Normally used to increase the power output
from a given engine displacement, but can
also be used primarily to reduce exhaust
emissions (as on VW’s “Umwelt” Diesel
engine).
UUniversal joint or U-jointA double-pivoted
connection for transmitting power from a
driving to a driven shaft through an angle. A U-
joint consists of two Y-shaped yokes and a
cross-shaped member called the spider.
VValveA device through which the flow of
liquid, gas, vacuum, or loose material in bulk
may be started, stopped, or regulated by a
movable part that opens, shuts, or partiallyobstructs one or more ports or passageways.
A valve is also the movable part of such a
device.
Valve clearanceThe clearance between the
valve tip (the end of the valve stem) and the
rocker arm or tappet. The valve clearance is
measured when the valve is closed.
Vernier caliperA precision measuring
instrument that measures inside and outside
dimensions. Not quite as accurate as a
micrometer, but more convenient.
ViscosityThe thickness of a liquid or its
resistance to flow.
VoltA unit for expressing electrical “pressure”
in a circuit. One volt that will produce a current
of one ampere through a resistance of one
ohm.
WWeldingVarious processes used to join metal
items by heating the areas to be joined to a
molten state and fusing them together. For
more information refer to the Haynes
Automotive Welding Manual.
Wiring diagramA drawing portraying the
components and wires in a vehicle’s electrical
system, using standardised symbols. For
more information refer to the Haynes
Automotive Electrical and Electronic Systems
Manual.