1997 JAGUAR XJ6 ad blue

reveal valuable information about the condition
of the engine (see illustration).
2Bearing failure occurs because of lack of
lubrication, the presence of dirt or other foreign
particles, overloading the engine and corrosion.
Regardless of the cause of failure, it must be
corrected before the engine is reassembled to
prevent it from happening again.
3When examining the bearings, remove
them from the engine block, the main bearing
caps, the connecting rods and the rod caps
and lay them out on a clean surface in the
same general position as their location in the
engine. This will enable you to match any
bearing problems with the corresponding
crankshaft journal.
4Dirt and other foreign particles get into the
engine in a variety of ways. It may be left in
the engine during assembly, or it may pass
through filters or the PCV system. It may get
into the oil, and from there into the bearings.
Metal chips from machining operations and
normal engine wear are often present.
Abrasives are sometimes left in engine
components after reconditioning, especially
when parts are not thoroughly cleaned using
the proper cleaning methods. Whatever the
source, these foreign objects often end up
embedded in the soft bearing material and are
easily recognised. Large particles will not
embed in the bearing and will score or gouge
the bearing and journal. The best prevention
for this cause of bearing failure is to clean all
parts thoroughly and keep everything
spotlessly clean during engine assembly.
Frequent and regular engine oil and filter
changes are also recommended.5Lack of lubrication (or lubrication
breakdown) has a number of interrelated
causes. Excessive heat (which thins the oil),
overloading (which squeezes the oil from the
bearing face) and oil leakage or throw off
(from excessive bearing clearances, worn oil
pump or high engine speeds) all contribute to
lubrication breakdown. Blocked oil passages,
which usually are the result of misaligned oil
holes in a bearing shell, will also oil starve a
bearing and destroy it. When lack of
lubrication is the cause of bearing failure, the
bearing material is wiped or extruded from the
steel backing of the bearing. Temperatures
may increase to the point where the steel
backing turns blue from overheating.
6Driving habits can have a definite effect on
bearing life. Low speed operation in too high a
gear (labouring the engine) puts extremely
high loads on bearings, which tends to
squeeze out the oil film. These loads cause
the bearings to flex, which produces fine
cracks in the bearing face (fatigue failure).
Eventually the bearing material will loosen in
pieces and tear away from the steel backing.
Short trip driving leads to corrosion of
bearings because insufficient engine heat is
produced to drive off the condensed water
and corrosive gases. These products collect
in the engine oil, forming acid and sludge. As
the oil is carried to the engine bearings, the
acid attacks and corrodes the bearing
material.
7Incorrect bearing refitting during engine
assembly will lead to bearing failure as well.
Tight-fitting bearings leave insufficient bearing
oil clearance, and this will lead to oilstarvation. Dirt or foreign particles trapped
behind a bearing insert result in high spots on
the bearing which lead to failure.
Selection
8If the original bearings are worn or
damaged, or if the oil clearances are incorrect
(see Sections 23 or 25), the following
procedures should be used to select the
correct new bearings for engine reassembly.
However, if the crankshaft has been reground,
new undersize bearings must be installed -
the following procedure should not be used if
undersize bearings are required! The
automotive machine workshop that
reconditions the crankshaft will provide or
help you select the correct-size bearings.
Regardless of how the bearing sizes are
determined, use the oil clearance, measured
with Plastigage, as a guide to ensure the
bearings are the right size.
9If you need to use a STANDARD size main
or big-end bearing, refit one that has the same
number as the original bearing. Note:4.0 litre
engines after #164637 have sized crankshafts
and bearings in three grades, indicated by
colour and letter. The codes are stamped into
the front throw of the crankshaft(see
illustration). Match replacement bearings by
the colour codes: pink (P), white (W) or
green (G) for main bearings; red (R), yellow (Y)
or blue (B) for the three grades of big-end
bearings.
10Remember, the oil clearance is the final
judge when selecting new bearing sizes. If you
have any questions or are unsure which
bearings to use, get help from a dealer parts
or service department.
2B•14 Engine removal and overhaul procedures
3261 Jaguar XJ6 20.1 When inspecting the main and big-end bearings, look for
these problems
20.9 Later model 4.0 litre engines have graded journals and
bearings, with the markings indicated on the front throw of the
crankshaft - “A” indicates the front of the engine, “B” indicates
the codes for the main journals/bearings, and “C” indicates the
connecting rod journal grades

3261 Jaguar XJ6
Use of EnglishREF•3
As the main part of this book has been written in the US, it uses the appropriate US component names, phrases, and spelling. Some of these
differ from those used in the UK. Normally, these cause no difficulty, but to make sure, a glossary is printed below. When ordering spare parts,
remember the parts list may use some of these words:
AMERICAN ENGLISH
Aluminum Aluminium
Antenna Aerial
Authorized Authorised
Auto parts stores Motor factors
Axleshaft Halfshaft
Back-up Reverse
Barrel Choke/venturi
Block Chock
Box-end wrench Ring spanner
Bushing Bush
Carburetor Carburettor
Center Centre
Coast Freewheel
Color Colour
Convertible Drop head coupe
Cotter pin Split pin
Counterclockwise Anti-clockwise
Countershaft (of gearbox) Layshaft
Dashboard Facia
Denatured alcohol Methylated spirit
Dome lamp Interior light
Driveaxle Driveshaft
Driveshaft Propeller shaft
Fender Wing/mudguard
Firewall Bulkhead
Flashlight Torch
Float bowl Float chamber
Floor jack Trolley jack
Freeway, turnpike etc Motorway
Freeze plug Core plug
Frozen Seized
Gas tank Petrol tank
Gasoline (gas) Petrol
Gearshift Gearchange
Generator (DC) Dynamo
Ground (electrical) Earth
Header Exhaust manifold
Heat riser Hot spot
High Top gear
Hood (engine cover) Bonnet
Installation Refitting
Intake Inlet
Jackstands Axle stands
Jumper cable Jump lead
Keeper Collet
Kerosene Paraffin
Knock pin Roll pin
Lash Clearance
Lash Free-play
Latch Catch
Latches Locks
License plate Number plate
Light Lamp
Lock (for valve spring retainer) Split cotter (for valve spring cap)
Lopes Hunts
Lug nut/bolt Wheel nut/bolt
Metal chips or debris Swarf
Misses Misfires
AMERICAN ENGLISH
Muffler Silencer
Odor Odour
Oil pan Sump
Open flame Naked flame
Panel wagon/van Van
Parking brake Handbrake
Parking light Sidelight
Pinging Pinking
Piston pin or wrist pin Gudgeon pin
Piston pin or wrist pin Small end, little end
Pitman arm Drop arm
Power brake booster Servo unit
Primary shoe (of brake) Leading shoe (of brake)
Prussian blue Engineer’s blue
Pry Prise (force apart)
Prybar Lever
Prying Levering
Quarter window Quarterlight
Recap Retread
Release cylinder Slave cylinder
Repair shop Garage
Replacement Renewal
Ring gear (of differential) Crownwheel
Rocker panel (beneath doors) Sill panel (beneath doors)
Rod bearing Big-end bearing
Rotor/disk Disc (brake)
Secondary shoe (of brake) Trailing shoe (of brake)
Sedan Saloon
Setscrew, Allen screw Grub screw
Shock absorber, shock Damper
Snap-ring Circlip
Soft top Hood
Spacer Distance piece
Spare tire Spare wheel
Spark plug wires HT leads
Spindle arm Steering arm
Stabilizer or sway bar Anti-roll bar
Station wagon Estate car
Stumbles Hesitates
Tang or lock Tab washer
Throw-out bearing Thrust bearing
Tie-rod or connecting rod (of steering) Trackrod
Tire Tyre
Transmission Gearbox
Troubleshooting Fault finding/diagnosis
Trunk Boot (luggage compartment)
Turn signal Indicator
TV (throttle valve) cable Kickdown cable
Unpublicized Unpublicised
Valve cover Rocker cover
Valve lifter Tappet
Valve lifter or tappet Cam follower or tappet
Vapor Vapour
Vise Vice
Wheel cover Roadwheel trim
Whole drive line Transmission
Windshield Windscreen
Wrench Spanner

3261 Jaguar XJ6
MOT test checksREF•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