3261 Jaguar XJ6
REF•16Fault finding
6 Suspension and steering systems
5 Braking system (continued)
Brake pedal feels spongy when depressed
m mAir in hydraulic lines (Chapter 9).
m mMaster cylinder mounting bolts loose (Chapter 9).
m mMaster cylinder defective (Chapter 9).
Brake pedal travels to the floor - no resistance
m
mLittle or no fluid in the master cylinder reservoir caused by leaking
caliper piston(s), damaged or disconnected brake lines (Chapter 9).
Handbrake does not hold
m mHandbrake cable or handbrake shoes improperly adjusted
(Chapter 9).
m mHandbrake shoes need replacement (Chapter 9).
Note:Before attempting to diagnose the suspension and steering
systems, perform the following preliminary checks:
a) Tyres for wrong pressure and uneven wear.
b) Steering universal joints from the column to the steering gear for
loose connectors or wear.
c) Front and rear suspension and the rack and pinion assembly for
loose or damaged parts.
d) Out-of-round or out-of-balance tyres, bent rims and loose and/or
rough wheel bearings.
Vehicle pulls to one side
m mMismatched or uneven tyres (Chapter 10).
m mBroken or sagging springs (Chapter 10).
m mWheel alignment out of specifications (Chapter 10).
m mFront brakes dragging (Chapter 9).
Abnormal or excessive tyre wear
m
mWheel alignment out of specifications (Chapter 10).
m mSagging or broken springs (Chapter 10).
m mTyre out-of-balance (Chapter 10).
m mWorn shock absorber (Chapter 10).
m mOverloaded vehicle.
m mTyres not rotated regularly.
Wheel makes a “thumping” noise
m
mBlister or bump on tyre (Chapter 10).
m mImproper shock absorber action (Chapter 10).
Shimmy, shake or vibration
m
mTyre or wheel out-of-balance or out-of-round (Chapter 10).
m mLoose, worn or out-of-adjustment wheel bearings (Chapter 1).
m mWorn tie-rod ends (Chapter 10).
m mWorn balljoints (Chapter 10).
m mExcessive wheel runout (Chapter 10).
m mBlister or bump on tyre (Chapter 10).
Hard steering
m
mLack of lubrication at balljoints, tie-rod ends and rack-and-pinion
assembly (Chapter 1).
m mFront wheel alignment (Chapter 10).
m mLow tyre pressure(s) (Chapter 1).
Poor returnability of steering to centre
m
mLack of lubrication at balljoints and tie-rod ends (Chapter 1).
m mBinding in balljoints (Chapter 10).
m mBinding in steering column (Chapter 10).
m mLack of lubricant in rack-and-pinion assembly (Chapter 10).
m mFront wheel alignment (Chapter 10).
Abnormal noise at the front end
m
mLack of lubrication at balljoints and tie-rod ends (Chapter 1).
m mDamaged shock absorber mounting (Chapter 10).m mWorn control arm bushings or tie-rod ends (Chapter 10).
m mLoose stabiliser bar (Chapter 10).
m mLoose wheel nuts (Chapter).
m mLoose suspension bolts (Chapter 10).
Wander or poor steering stability
m
mMismatched or uneven tyres (Chapter 10).
m mLack of lubrication at balljoints and tie-rod ends (Chapter 1).
m mWorn shock absorbers (Chapter 10).
m mLoose stabiliser bar (Chapter 10).
m mBroken or sagging springs (Chapter 10).
m mFront or rear wheel alignment (Chapter 10).
Erratic steering when braking
m
mWheel bearings worn (Chapter 1).
m mBroken or sagging springs (Chapter 10).
m mLeaking wheel cylinder or caliper (Chapter 9).
m mWarped discs (Chapter 9).
Excessive pitching and/or rolling around corners
or during braking
m mLoose stabiliser bar (Chapter 10).
m mWorn shock absorbers or mounts (Chapter 10).
m mBroken or sagging springs (Chapter 10).
m mOverloaded vehicle.
Suspension bottoms
m
mOverloaded vehicle.
m mWorn shock absorbers (Chapter 10).
m mIncorrect, broken or sagging springs (Chapter 10).
m mDefective power hydraulic system or leaking rear shock absorbers
(Chapter 10).
Cupped tyres (wear on both edges)
m mFront wheel or rear wheel alignment (Chapter 10).
m mWorn shock absorbers (Chapter 10).
m mWheel bearings worn (Chapter 10).
m mExcessive tyre or wheel runout (Chapter 10).
m mWorn balljoints (Chapter 10).
Excessive tyre wear on outside edge
m
mInflation pressures incorrect (Chapter 1).
m mExcessive speed in turns.
m mFront end alignment incorrect (excessive toe-in). Have
professionally aligned.
m mSuspension arm bent or twisted (Chapter 10).
Excessive tyre wear on inside edge
m
mInflation pressures incorrect (Chapter 1).
m mFront end alignment incorrect (toe-out). Have professionally
aligned.
m mLoose or damaged steering components (Chapter 10).
3261 Jaguar XJ6
Fault findingREF•17
6 Suspension and steering systems (continued)
Tyre tread worn in one place
m mTyres out-of-balance.
m mDamaged or buckled wheel. Inspect and replace if necessary.
m mDefective tyre (Chapter 1).
Excessive play or looseness in steering system
m
mWheel bearing(s) worn (Chapter 10.m mTie-rod end loose or worn (Chapter 10).
m mSteering gear loose or worn (Chapter 10).
Rattling or clicking noise in rack-and-pinion
m
mInsufficient or improper power steering fluid in steering system
(Chapter 10).
m mSteering gear mounts loose (Chapter 10).
7 Electrical system
Battery will not hold a charge
m
mAlternator drivebelt defective or not adjusted properly (Chapter 1).
m mElectrolyte level low (Chapter 1).
m mBattery terminals loose or corroded (Chapter 1).
m mAlternator not charging properly (Chapter 5).
m mLoose, broken or faulty wiring in the charging circuit (Chapter 5).
m mShort in vehicle wiring (Chapters 5 and 12).
m mInternally defective battery (Chapters 1 and 5).
m mDamaged left rear window harness shorting against glass rail
inside door, causing battery to drain (Chapter 12).
Charge warning light fails to go out
m mFaulty alternator or charging circuit (Chapter 5).
m mAlternator drivebelt defective or out of adjustment (Chapter 1).
m mAlternator voltage regulator inoperative (Chapter 5).
Charge warning light fails to come on
when key is turned on
m mWarning light bulb defective (Chapter 12).
m mFault in the printed circuit, dash wiring or bulb holder (Chapter 12).
3261 Jaguar XJ6
REF•20Glossary of technical terms
GGapThe distance the spark must travel in
jumping from the centre electrode to the side
electrode 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.
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 to
the 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.
Adjusting spark plug gap
Plastigage
Gasket