3261 Jaguar XJ6
Glossary of technical termsREF•19
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 clipDDiagnostic 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.
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.
F
Fan 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.Catalytic converter
Crankshaft assembly
Accessory drivebelts
Feeler blade
3261 Jaguar XJ6
Glossary of technical termsREF•21
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
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. On
front 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 partially
obstructs 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.
Serpentine drivebelt
3261 Jaguar XJ6
REF•22Index
AABS fault finding -9•2
Accelerator cable -4•8
Acknowledgements -0•4
Aerial - 12•8
Air cleaner -1•14, 4•7
Air conditioning -3•2, 3•7, 3•10, 3•11, 3•13, 3•14
Air induction system -4•9
Air Injector Reactor (AIR) system -6•8
Air intake plenum -4•13
Airbag - 0•5, 12•14
Alternator -5•6
Amplifier -5•3
Anti-lock Brake system (ABS) -9•2
Anti-roll bar - 10•3
Anti-theft system - REF•1
Antifreeze -0•11, 0•16, 1•2, 1•20, 3•2
Asbestos -0•5
ATF -0•16
Automatic transmission-7•1et seq
fault finding - 7•1, REF•15
fluid - 0•16, 1•2, 1•11, 1•19
filter - 1•19
Auxiliary shaft -2A•8
BBalljoints - 10•4
Battery -0•5, 0•15, 1•9, 5•1, 5•1
Big-end bearings -2B•13, 2B•17
Bleeding
brake system - 9•10
power steering - 10•11
Block -2B•10, 2B•11
Blower motors -3•7
Body corrosion - REF•11
Body electrical system- 12•1et seq
Bodywork and fittings- 11•1et seq
Bonnet - 11•3, 11•4
Boot - 11•7
lid - 11•3, 11•6, 11•7,
Boots (steering) - 10•9
Brake fluid -0•12, 0•16, 1•20
Brake lights - 12•12
switch - 9•13
Brake servo -1•12
Braking system-1•12, 9•1et seq
fault finding - REF•15, REF•16
MOT checks - REF•8 to REF•10
Bulbs -0•15, 12•11
Bumpers - 11•5
Burning -0•5
CCables -4•8, 5•2, 7•2, 7•4, 9•10, 9•11, 11•4, 11•10
Calipers -9•3
Camshafts -2A•9
Capacities -1•2
Carpets - 11•1
Cassette - REF•1
Catalytic converter -6•12
Central locking - 12•13
Centre console - 11•11
Charcoal canister -6•11
Charging -1•10
Charging system -5•5
Circuit breakers - 12•3
CO emissions (mixture) - REF•11
Coil (HT) -5•3
Coil spring - 10•5, 10•6
Compression check -2B•3
Compressor -3•13
Condenser -3•13
Connecting rods -2B•9, 2B•12, 2B•17, 2B•18
Console - 11•11, 11•12
Continuity check - 12•2
Control arms - 10•5, 10•6, 10•8
Conversion factors - REF•2
Coolant -0•11, 0•16, 1•2, 1•20, 3•2
Coolant reservoir -3•4, 3•5
Coolant temperature sensor -6•3
Cooling fans -3•3
Cooling system fault finding - REF•14
Cooling,heating and air conditioning systems-3•1et seq
Courtesy lights - 12•12
Cowl cover - 11•14
Crankcase ventilation system -1•16, 6•11
Crankshaft -2A•5, 2A•17, 2B•10, 2B•13, 2B•16
position sensor - 6•7
Cruise control - 12•13
Crushing -0•5
Cylinder head -2A•13, 2B•6, 2B•7, 2B•8
Cylinder honing -2B•12
DDashboard - 11•13
Dents - 11•2
Differential -8•1, 8•5
oil - 1•2, 1•11, 1•20
Dimensions - REF•1
Direction indicators - 12•4, 12•11, 12•12
Discs -9•4
Distributor -5•4
Doors - 11•7, 11•8, 11•9, 11•10, 11•10, REF•9
Drivebelt -1•16
Driveplate -2A•16
Driveshafts -8•1, 8•4, 8•5, REF•10
Drivetrain-1•14, 8•1et seq
Note:References throughout this index are in the form - “Chapter number” • “page number”