air condition JAGUAR XJ6 1997 2.G User Guide

1 General information
1This Chapter is designed to help the home
mechanic maintain his/her vehicle for safety,
economy, long life and peak performance.
2The Chapter contains a master
maintenance schedule, followed by Sections
dealing specifically with each task in the
schedule. Visual checks, adjustments,
component renewal and other helpful items
are included. Refer to the accompanying
illustrations of the engine compartment and
the underside of the vehicle for the locations
of the various components.
3Servicing your vehicle in accordance with
the mileage/time maintenance schedule and
the following Sections will provide a planned
maintenance programme, which should result
in a long and reliable service life. This is a
comprehensive plan, so maintaining some
items but not others at the specified service
intervals, will not produce the same results.
4As you service your vehicle, you will
discover that many of the procedures can -
and should - be grouped together, because of
the particular procedure being performed, or
because of the proximity of two otherwise-
unrelated components to one another. For
example, if the vehicle is raised for any
reason, the exhaust can be inspected at the
same time as the suspension and steering
components.
5The first step in this maintenance
programme is to prepare yourself before the
actual work begins. Read through all theSections relevant to the work to be carried out,
then make a list and gather all the parts and
tools required. If a problem is encountered,
seek advice from a parts specialist, or a dealer
service department.
2 Intensive maintenance
1If, from the time the vehicle is new, the
routine maintenance schedule is followed
closely, and frequent checks are made of fluid
levels and high-wear items, as suggested
throughout this manual, the engine will be
kept in relatively good running condition, and
the need for additional work will be minimised.
2It is possible that there will be times when
the engine is running poorly due to the lack of
regular maintenance. This is even more likely
if a used vehicle, which has not received
regular and frequent maintenance checks, is
purchased. In such cases, additional work
may need to be carried out, outside of the
regular maintenance intervals.
3If engine wear is suspected, a compression
test (refer to Chapter 2) will provide valuable
information regarding the overall performance
of the main internal components. Such a test
can be used as a basis to decide on the extent
of the work to be carried out. If, for example, a
compression test indicates serious internal
engine wear, conventional maintenance as
described in this Chapter will not greatly
improve the performance of the engine, and
may prove a waste of time and money, unless
extensive overhaul work is carried out first.4The following series of operations are those
which are most often required to improve the
performance of a generally poor-running
engine:
Primary operations
a) Clean, inspect and test the battery
(Section 6).
b) Check all the engine-related fluids (refer
to “Weekly checks”).
c) Check the condition and tension of the
auxiliary drivebelt (Section 21).
d) Renew the spark plugs (Section 16).
e) Inspect the distributor cap and rotor arm
(Section 19).
f) Check the condition of the air filter, and
renew if necessary (Section 17).
g) Renew the fuel filter (Section 18).
h) Check the condition of all hoses, and
check for fluid leaks (Section 7).
i) Check the exhaust gas emissions (see
Chapter 6).
5If the above operations do not prove fully
effective, carry out the following secondary
operations:
Secondary operations
All items listed under “Primary operations”,
plus the following:
a) Check the charging system (refer to
Chapter 5).
b) Check the ignition system (refer to
Chapter 5).
c) Check the fuel system (refer to Chapter 4).
d) Renew the distributor cap and rotor arm
(Section 19).
e) Renew the ignition HT leads (Section 19).
1•6Maintenance procedures
3261 Jaguar XJ6
Every 7500 miles (12 000 km) or 6 months
3 Engine oil and filter renewal
2
1Frequent oil changes are the best
preventive maintenance the home mechanic
can give the engine, because ageing oil
becomes diluted and contaminated, which
leads to premature engine wear.
2Make sure that you have all the necessary
tools before you begin this procedure (see
illustration). You should also have plenty of
rags or newspapers handy for mopping up
any spills.
3Access to the underside of the vehicle is
greatly improved if the vehicle can be lifted on
a hoist, driven onto ramps or supported by
axle stands.
4If this is your first oil change, get under the
vehicle and familiarise yourself with the
location of the oil drain plug. The engine and
3.2 These tools are required when
changing the engine oil and filter
1 Drain pan - It should be fairly shallow in
depth, but wide in order to prevent spills
2 Rubber gloves - When removing the drain
plug and filter, it is inevitable that you will
get oil on your hands (the gloves will
prevent burns)
3 Breaker bar - Sometimes the oil drain plug
is pretty tight and a long breaker bar is
needed to loosen it
4 Socket – To be used with the breaker bar
or a ratchet (must be the correct size to fit
the drain plug)
5 Filter wrench - This is a metal band-type
wrench, which requires clearance around
the filter to be effective
6 Filter wrench - This type fits on the bottom
of the filter and can be turned with a
ratchet or breaker bar (different size
spanners are available for different types of
filters)

3Inspect each of the new plugs for defects. If
there are any signs of cracks in the porcelain
insulator of a plug, don’t use it.
4Check the electrode gaps of the new plugs.
Check the gap by inserting the wire gauge of
the proper thickness between the electrodes
at the tip of the plug (see illustration). The
gap between the electrodes should be
identical to that listed in this Chapter’s
Specifications or on the VECI label (as
applicable). If the gap is incorrect, use the
notched adjuster on the feeler gauge body to
bend the curved side electrode slightly (see
illustration).
5If the side electrode is not exactly over the
centre electrode, use the notched adjuster to
align them.Caution: If the gap of a new plug must be
adjusted, bend only the base of the earth
electrode - do not touch the tip.
Removal
6To prevent the possibility of mixing up
spark plug leads, work on one spark plug at a
time. Remove the lead and boot from one
spark plug. Grasp the boot - not the lead - as
shown, give it a half twisting motion and pull
straight up (see illustration).
7If compressed air is available, blow any dirt
or foreign material away from the spark plug
area before proceeding (a common bicycle
pump will also work).
8Remove the spark plug (see illustration).9Whether you are replacing the plugs at this
time or intend to re-use the old plugs,
compare each old spark plug with the chart
shown on the inside back cover of this manual
to determine the overall running condition of
the engine.
Refitting
10Prior to refitting, apply a coat of anti-seize
compound to the plug threads (see
illustration). It’s often difficult to insert spark
plugs into their holes without cross-threading
them. To avoid this possibility, fit a short piece
of 3/8-inch internal diameter (ID) rubber hose
over the end of the spark plug (see Haynes
Hint). The flexible hose acts as a universal
joint to help align the plug with the plug hole.
Should the plug begin to cross-thread, the
hose will slip on the spark plug, preventing
thread damage. Tighten the plug to the torque
listed in this Chapter’s Specifications. In the
absence of a torque wrench, tighten each
plug until you feel it seat, and then by a further
quarter-turn only. Do not overtighten the
spark plugs.
11Attach the plug lead to the new spark
plug, again using a twisting motion on the
boot until it is firmly seated on the end of the
spark plug.
12Follow the above procedure for the
remaining spark plugs, replacing them one at
a time to prevent mixing up the spark plug
leads.
1•8Every 7500 miles or 6 months
4.4a Spark plug manufacturers
recommend using a wire-type gauge when
checking the gap - if the wire does not
slide between the electrodes with a slight
drag, adjustment is required4.4b To change the gap, bend the side
electrode only, as indicated by the arrows,
and be very careful not to crack or chip the
porcelain insulator surrounding the
centre electrode4.6 When removing the spark plug leads,
grasp only the boot and use a
twisting/pulling motion
4.8 Use a spark plug socket with a long
extension to unscrew the spark plugs
3261 Jaguar XJ6
4.1 Tools required for changing
spark plugs
1 Spark plug socket - This will have special
padding inside to protect the spark plug
porcelain insulator
2 Torque wrench - Although not mandatory,
use of this tool is the best way to ensure
that the plugs are tightened properly
3 Ratchet - to fit the plug socket
4 Extension - Depending on model and
accessories, you may need special
extensions and universal joints to reach
one or more of the plugs
5 Spark plug gap gauge - This gauge for
checking the gap comes in a variety of
styles. Make sure the gap for your engine
is included
4.10 Apply a coat of anti-seize compound
to the spark plug threads
A length of 3/8-inch ID rubber hose will
save time and prevent damaged
threads when refitting the spark plugs

silencer and catalytic converter. If the
components can come in contact with the
body or suspension parts, secure the exhaust
system with new mounts.
5Check the running condition of the engine
by inspecting inside the end of the tailpipe.
The exhaust deposits here are an indication of
engine state-of-tune. If the pipe is black and
sooty or coated with white deposits, the
engine is in need of a tune-up, including a
thorough fuel system inspection.
11 Braking system - general
check and adjustment
2
Warning: The dust created by
the brake system may contain
asbestos, which is harmful to
your health. Never blow it out
with compressed air and don’t inhale any
of it. An approved filtering mask should be
worn when working on the brakes. Do not,
under any circumstances, use petroleum-
based solvents to clean brake parts. Use
brake system cleaner only! Try to use non-
asbestos replacement parts whenever
possible.
Note: For detailed photographs of the brake
system, refer to Chapter 9.
1In addition to the specified intervals, the
brakes should be inspected every time the
wheels are removed or whenever a defect is
suspected. Any of the following symptoms
could indicate a potential brake system
defect: The vehicle pulls to one side when the
brake pedal is depressed; the brakes make
squealing or dragging noises when applied;
brake pedal travel is excessive; the pedal
pulsates; brake fluid leaks, usually onto the
inside of the tyre or wheel.
2The disc brakes have built-in electrical wear
indicators which cause a warning lamp to
illuminate on the instrument panel when
they’re worn to the renewal point. When the
warning light comes on, replace the pads
immediately or expensive damage to the
discs can result.
3Loosen the wheel nuts.
4Raise the vehicle and place it securely on
axle stands.
5Remove the wheels.
Disc brakes
6There are two pads (an outer and an inner)
in each caliper. The pads are visible through
inspection holes in each caliper (see Haynes
Hint).
7Check the pad thickness by looking at each
end of the caliper and through the inspection
hole in the caliper body. If the lining material is
less than the thickness listed in this Chapter’s
Specifications, replace the pads. Note:Keep
in mind that the lining material is riveted or
bonded to a metal backing plate and the metal
portion is not included in this measurement.8If it is difficult to determine the exact
thickness of the remaining pad material by the
above method, or if you are at all concerned
about the condition of the pads, remove the
caliper(s), then remove the pads from the
calipers for further inspection (see Chapter 9).
9Once the pads are removed from the
calipers, clean them with brake cleaner and
re-measure them with a ruler or a vernier
caliper.
10Measure the disc thickness with a
micrometer to make sure that it still has
service life remaining. If any disc is thinner
than the specified minimum thickness,
replace it (refer to Chapter 9). Even if the disc
has service life remaining, check its condition.
Look for scoring, gouging and burned spots. If
these conditions exist, remove the disc and
have it resurfaced (see Chapter 9).
11Before refitting the wheels, check all
brake lines and hoses for damage, wear,
deformation, cracks, corrosion, leakage,
bends and twists, particularly in the vicinity of
the rubber hoses at the calipers (see
illustration). Check the clamps for tightness
and the connections for leakage. Make sure
that all hoses and lines are clear of sharp
edges, moving parts and the exhaust system.
If any of the above conditions are noted,
repair, reroute or replace the lines and/or
fittings as necessary (see Chapter 9).
Hydraulic brake servo check
12Sit in the driver’s seat and perform the
following sequence of tests.
13Start the engine, run it for about a minute
and turn it off. Then firmly depress the brake
several times - the pedal travel should
decrease with each application.
14With the brake fully depressed, start the
engine - the pedal should move down a little
when the engine starts.
15Depress the brake, stop the engine and
hold the pedal in for about 30 seconds - the
pedal should neither sink nor rise.
16If your brakes do not operate as
described above when the preceding tests
are performed, the brake servo is either in
need of repair or has failed. Refer to Chapter 9
for the removal procedure.
Handbrake
17Slowly pull up on the handbrake and
count the number of clicks you hear until the
handle is up as far as it will go. The
adjustment should be within the specified
number of clicks listed in this Chapter’s
Specifications. If you hear more or fewer
clicks, it’s time to adjust the handbrake (refer
to Chapter 9).
18An alternative method of checking the
handbrake is to park the vehicle on a steep hill
with the handbrake set and the transmission
in Neutral (be sure to stay in the vehicle during
this check!). If the handbrake cannot prevent
the vehicle from rolling, it is in need of
adjustment (see Chapter 9). Whenever a fault
is suspected, the brake discs should be
removed and the handbrake assemblies
themselves should be visually inspected.
12 Steering
and suspension check
2
Note: The steering linkage and suspension
components should be checked periodically.
Worn or damaged suspension and steering
linkage components can result in excessive
and abnormal tyre wear, poor ride quality and
vehicle handling and reduced fuel economy.
For detailed illustrations of the steering and
suspension components, refer to Chapter 10.
With the wheels on the ground
1Park the vehicle on level ground, turn the
engine off and set the handbrake. Check the
tyre pressures and check that the wheel nuts
are tightened to the specified torque.
2Push down at one corner of the vehicle,
then release it while noting the movement of
the body. It should stop moving and come to
rest in a level position with one or two
bounces. When bouncing the vehicle up and
down, listen for squeaks and noises from the
suspension components.
3If the vehicle continues to move up-and-
down or if it fails to return to its original
1•12Every 7500 miles or 6 months
11.11 Check along the brake hoses
and at each fitting (arrowed) for
deterioration and cracks
3261 Jaguar XJ6
You will find an inspection hole like this
in each caliper - placing a ruler across
the hole should enable you to determine
the thickness of remaining pad material
for both inner and outer pads

16 Spark plug renewal
2
Refer to Section 4, renewing the plugs
regardless of their apparent condition.
17 Air cleaner element renewal
1
1The air filter is located inside a housing at
the left side of the engine compartment. To
remove the air filter, release the four spring
clips that secure the two halves of the air
cleaner housing together, then lift the cover
up and remove the air filter element (see
illustration).
Caution: Never drive the car with the air
cleaner removed. Excessive engine wear
could result and backfiring could even
cause a fire under the bonnet.
2Wipe out the inside of the air cleaner
housing.
3Place the new filter into the air cleaner
housing, making sure it seats properly.
4Refitting the cover is the reverse of removal.
18 Fuel filter renewal
2
Warning: Petrol is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system.
Don’t smoke or allow open flames or bare
light bulbs near the work area, and don’t
work in a garage where a natural gas-typeappliance (such as a water heater or
clothes dryer) with a pilot light is present.
Since petrol is carcinogenic, wear latex
gloves when there’s a possibility of being
exposed to fuel, and, if you spill any fuel on
your skin, rinse it off immediately with soap
and water. Mop up any spills immediately
and do not store fuel-soaked rags where
they could ignite. The fuel system is under
constant pressure, so, if any fuel lines are
to be disconnected, the fuel pressure in
the system must be relieved first (see
Chapter 4 for more information). When you
perform any kind of work on the fuel
system, wear safety glasses and have a
Class B type fire extinguisher on hand.
1The canister type filter is mounted
underneath the car on the passenger’s side
frame rail just in front of the left rear tyre.
2Depressurise the fuel system (refer to
Chapter 4), then disconnect the cable from
the negative terminal of the battery.
3On 1988 to 1990 models, detach the banjo
bolt from the outlet side of the filter then
remove the union from the inlet side of the
filter. Unscrew the filter mounting bolt and
remove the filter (see illustration).
4On 1991 to 1994 models, the fuel filter has
quick-disconnect fittings that do not require 8Clean and lubricate the handbrake cable,
along with the cable guides and levers. This
can be done by smearing some of the chassis
grease onto the cable and its related parts
with your fingers.
9Open the bonnet and smear a little chassis
grease on the bonnet latch mechanism. Have
an assistant pull the bonnet release lever from
inside the car as you lubricate the cable at the
latch.
10Lubricate all the hinges (door, bonnet,
etc.) with engine oil to keep them in proper
working order.
11The key lock cylinders can be lubricated
with spray graphite or silicone lubricant, which
is available at motor factors.12Lubricate the door weather-stripping with
silicone spray. This will reduce chafing and
retard wear.
15 Road test
1
Instruments and electrical
equipment
1Check the operation of all instruments and
electrical equipment.
2Make sure that all instruments read
correctly, and switch on all electrical
equipment in turn, to check that it functions
properly.
Steering and suspension
3Check for any abnormalities in the steering,
suspension, handling or road “feel”.
4Drive the car, and check that there are no
unusual vibrations or noises.
5Check that the steering feels positive, with
no excessive “sloppiness”, or roughness, and
check for any suspension noises when
cornering and driving over bumps.
Drivetrain
6Check the performance of the engine and
transmission, listening for any unusual noises.7Make sure that the engine runs smoothly
when idling, and that there is no hesitation
when accelerating.
8Check that the gear changing action of the
transmission is smooth and progressive and
that the drive is taken up smoothly from a
standing start.
Braking system
9Make sure that the car does not pull to one
side when braking, and that the wheels do not
lock prematurely when braking hard.
10Check that there is no vibration through
the steering when braking.
11Check that the handbrake operates
correctly without excessive movement of the
lever, and that it holds the car stationary on a
slope.
12Test the operation of the brake servo unit
as follows. With the engine off, depress the
footbrake four or five times to exhaust the
vacuum. Hold the brake pedal depressed, then
start the engine. As the engine starts, there
should be a noticeable “give” in the brake
pedal as vacuum builds up. Allow the engine to
run for at least two minutes, and then switch it
off. If the brake pedal is depressed now, it
should be possible to detect a hiss from the
servo as the pedal is depressed. After about
four or five depressions, no further hissing
should be heard, and the pedal should feel
considerably harder.
1•14Every 7500 miles or 6 months
17.1 Detach the clips and separate the
cover, then slide the filter element out of
the housing
3261 Jaguar XJ6
14.6 Grease fittings for the rear
driveshafts are located in the centre
on each U-joint
Every 15 000 miles (24 000 km) or 12 months

20 Crankcase ventilation
system check
1
Refer to Chapter 6.
21 Drivebelt check and renewal
2
Check
1The drivebelts, or V-belts as they are
sometimes called, are located at the front of
the engine and play an important role in the
overall operation of the vehicle and its
components. Due to their function and
material make-up, the belts are prone to
failure after a period of time and should be
inspected and adjusted periodically to prevent
major engine damage.
2The number of belts used on a particular
vehicle depends on the accessories installed.
The main belt transmits power from the
crankshaft to the water pump, alternator and
the power steering pump. The second belt
transmits power from the crankshaft to the air
conditioning compressor.
3With the engine off, open the bonnet and
locate the drivebelts. With a flashlight, check
each belt for separation of the adhesive
rubber on both sides of the core, core
separation from the belt side, a severed core,
separation of the ribs from the adhesive
rubber, cracking or separation of the ribs, and
torn or worn ribs or cracks in the inner ridges
of the ribs (see illustrations). Also check for
fraying and glazing, which gives the belt a
shiny appearance. Both sides of the belt
should be inspected, which means you will
have to twist the belt to check the underside.
Use your fingers to feel the belt where you
can’t see it. If any of the above conditions are
evident, replace the belt (go to paragraph 7).
4Check the belt tension by pushing firmly on
the belt with your thumb at a distance halfway
between the pulleys and note how far the beltcan be pushed (deflected). Measure this
deflection with a ruler (see illustration). As a
rule of thumb, if the distance from pulley
centre-to- pulley centre is between 7 and
11 inches, the belt should deflect 1/4-inch. If
the belt travels between pulleys spaced 12 to
16 inches apart, the belt should deflect
1/2-inch for a V-belt or 1/4-inch for a
serpentine belt.
Adjustment
5There are two belt tensioning mechanisms.
The first one adjusts the air conditioning
compressor belt, which is accessible from
underneath the car. The second tensioning
mechanism is above the alternator - it adjusts
the tension on the main belt (the water pump,
alternator and power steering pump belt).
6The air conditioning compressor and the
alternator each have a belt tensioning
mechanism and pivot bolt(s) which must be
loosened slightly to enable you to move the
component (see illustrations).
7After the bolts have been loosened, belt
tension can be adjusted by either loosening or
tightening the locknuts on the belt tensioning
adjustment rod (see illustration 21.6a and b).
Move the component away from the engine totighten the belt or toward the engine to loosen
the belt.
8Measure the belt tension using the method
described in paragraph 4. Repeat this
procedure until the drivebelt is adjusted
properly.
Renewal
9To replace a belt, loosen the drivebelt
adjustment rod and pivot bolt as described
above, slip the belt off the crankshaft pulley
and remove it. If you are replacing the
alternator/power steering pump belt, you’ll
have to remove the air conditioning
1•16Every 15 000 miles or 12 months
21.3a Small cracks in the underside of a
serpentine belt are acceptable -
lengthwise cracks, or missing pieces, are
cause for replacement
21.3b Here are some of the more common
problems associated with V-belts (check
the belts very carefully to prevent an
untimely breakdown)
21.4 Measuring drivebelt deflection with a
straightedge and ruler
21.6a To adjust the alternator/power
steering drivebelt, loosen the outer locknut
(arrowed) and the alternator pivot bolt -
turn the inner locknut anti-clockwise to
loosen or clockwise to tighten the belt21.6b To adjust the air conditioning
compressor drivebelt, loosen the outer
locknut (arrowed) and the compressor
pivot bolts - turn the inner locknut anti-
clockwise to loosen or clockwise to
tighten the belt
3261 Jaguar XJ6

5After the coolant stops flowing out of the
radiator, move the container under the engine
block drain plug. Remove the plug and let the
coolant in the block to drain (see illustration).
6While the coolant is draining from the
engine block, check the condition of the
radiator hoses, heater hoses and clamps
(refer to Section 7 if necessary).
7Replace any damaged clamps or hoses
(see Chapter 3).
Flushing
8Once the system is completely drained,
flush the radiator with fresh water from agarden hose until water runs clear at the drain.
The flushing action of the water will remove
sediments from the radiator but will not
remove more serious rust and scale from the
engine and cooling tube surfaces.
9These deposits can be removed by using
proprietary chemical cleaners. It should be
stressed, however, that these should only
need to be used if the system has been
neglected. Follow the procedure outlined in
their manufacturer’s instructions. If the
radiator is severely corroded, damaged or
leaking, it should be removed (see Chapter 3)
and taken to a radiator repair workshop.10On 1988 and 1989 models remove the
overflow hose from the coolant recovery
reservoir. Drain the reservoir and flush it with
clean water, then reconnect the hose (see
Chapter 3).
Refilling
11Close and tighten the radiator drain. Refit
and tighten the engine block drain plugs.
12Make sure the heater temperature control
is in the maximum heat position.
13Slowly refill the expansion tank with a
mixture of antifreeze and water until the
coolant reaches the base of the filler neck.
14Leave the expansion tank pressure cap
off and run the engine in a well-ventilated area
until the thermostat opens (coolant will begin
flowing through the radiator and the upper
radiator hose will become hot). Race the
engine two or three times under no load.
15Turn the engine off and let it cool. Add
more coolant mixture to bring the level back
up to the base of the filler neck.
16Squeeze the upper radiator hose to expel
air, then add more coolant mixture if
necessary. Refit the expansion tank pressure
cap.
17Start the engine, allow it to reach normal
operating temperature and check for leaks.
Every 2 years 1•21
1
3261 Jaguar XJ6
30.4 The radiator drain fitting (arrowed)
located at the bottom of the radiator30.5 The block drain plug (arrowed) is
located on the right side of the block

12Remove the four bolts in each camshaft
inner sprocket (see illustration). The bolts are
secured by sheetmetal “washer” plates. Bend
down the locking tabs with a hammer and
screwdriver tip to remove the bolts.
Caution: Stuff rags below the sprockets
while removing the bolts to prevent a bolt
from falling down into the front cover.
13Remove the two bolts retaining the upper
chain guide to the cylinder head (see
illustration).
14Pull the inner sprockets from each
camshaft (see illustration). Each camshaft
sprocket is comprised of an inner and outer,
each with a set of fine splines that lock them
together. The outer sprockets, with the teeth,
can rotate on the camshafts until the inner
sprocket bolts are tightened.
15Pull the outer sprockets from the
camshafts and allow the chain slacken.
16At this point the camshafts can be
carefully lifted straight up and off the cylinder
head. Take care not to nick any of the lobes or
journals during removal.
17Use a magnet to remove the lifters,
keeping them in order in a divided, numbered
box (see illustration). They must be returned
to their original location if reusing the original
camshafts!
18Removing the lifters exposes the
adjusting shims, sitting in a pocket in eachvalve spring retainer (see illustration). Keep
the shims with their matching lifters. Measure
the thickness of each shim with a micrometer
and record the measurements.
Inspection
19After the camshaft has been removed
from the engine, cleaned with solvent and
dried, inspect the bearing journals for uneven
wear, pitting and evidence of seizure. If the
journals are damaged, the bearing surfaces in
the cylinder head and caps may be damaged
as well, requiring renewal of the cylinder head.
20Measure the bearing journals with a
micrometer to determine if they are excessivelyworn or out-of-round (see illustration).
Compare the measurements to Specifications.
21Check the camshaft lobes for heat
discolouration, score marks, chipped areas,
pitting and uneven wear. Measure the lobe
heights with a micrometer and record the
measurements (see illustrations). If there is
variance of more than 0.005-inch, the
camshaft and lifters must be renewed. If the
lobes are in good condition, the camshaft can
be reused.
22Inspect the top, bottom and side surfaces
of the lifters for wear, grooving or scoring. If
the lifters are damaged, the camshaft and its
lifters must be renewed as a set.
Engine in-car repair procedures 2A•11
2A
10.13 Remove the two bolts and the upper
timing chain guide (arrowed)10.14 Pull the inner sprocket from the
outer sprocket of each camshaft
10.17 A magnet can be used to remove
the lifters (arrowed)10.18 The valve adjustment shims
(arrowed) fit into a pocket in the valve
spring retainer - use a magnet to remove
the shims and keep them with their
respective lifters10.20 Measure the bearing journals with a
micrometer to check diameter - measure
at several places around the journal to
check for taper or out-of-round
3261 Jaguar XJ6 10.12 Bend back the locking tabs
(arrowed) and remove the camshaft
sprocket bolts
10.21a Measure the camshaft lobe at its
greatest dimension . . .10.21b . . . and subtract the camshaft lobe
diameter at its smallest dimension to
obtain the lobe lift

Engine block
Deck warpage limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.076 mm (0.003 inch)
Cylinder bore diameter
Standard
Size group A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90.990 to 91.003 mm (3.5823 to 3.5828 inches)
Size group B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.005 to 91.018 mm (3.5829 to 3.5834 inches)
Oversize
0.25 mm (0.010 inch) OS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.259 to 91.272 mm (3.5929 to 3.5934 inches)
0.50 mm (0.020 inch) OS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.513 to 91.526 mm (3.6029 to 3.6034 inches)
Pistons and rings
Piston-to-bore clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.017 to 0.043 mm (0.0007 to 0.0017 inch)
Piston ring end gap
No.1 (top) compression ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.40 to 0.66 mm (0.016 to 0.026 inch)
No.2 (middle) compression ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.40 to 0.66 mm (0.016 to 0.026 inch)
Oil ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.30 to 0.55 mm (0.012 to 0.022 inch)
Piston ring groove clearance
No. 1 (top) compression ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.040 to 0.076 mm (0.0016 to 0.0030 inch)
No. 2 (middle) compression ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.040 to 0.076 mm (0.0016 to 0.0030 inch)
Torque wrench settingsNm lbf ft
Main bearing cap bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 to 142 100 to 105
Connecting rod cap nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 to 60 37 to 44
* Note:Refer to Part A for additional torque specifications.
2B•2 Engine removal and overhaul procedures
3261 Jaguar XJ6
1 General information
Included in this portion of Chapter 2 are the
general overhaul procedures for the cylinder
head and internal engine components.
The information ranges from advice
concerning preparation for an overhaul and
the purchase of replacement parts to detailed,
step-by-step procedures covering removal
and refitting of internal engine components
and the inspection of parts.
The following Sections have been written
based on the assumption that the engine has
been removed from the vehicle. For
information concerning in-vehicle engine
repair, as well as removal and refitting of the
external components necessary for the
overhaul, see Part A of this Chapter.
The Specifications included in this Part are
only those necessary for the inspection and
overhaul procedures which follow. Refer to
Part A for additional Specifications.
2 Engine overhaul-
general information
It’s not always easy to determine when, or if,
an engine should be completely overhauled,
as a number of factors must be considered.
High mileage is not necessarily an indication
that an overhaul is needed, while low mileage
doesn’t preclude the need for an overhaul.
Frequency of servicing is probably the most
important consideration. An engine that’s had
regular and frequent oil and filter changes, as
well as other required maintenance, will most
likely give many thousands of miles of reliableservice. Conversely, a neglected engine may
require an overhaul very early in its life.
Excessive oil consumption is an indication
that piston rings, valve seals and/or valve
guides are in need of attention. Make sure that
oil leaks aren’t responsible before deciding
that the rings and/or guides are bad. Perform a
cylinder compression check to determine the
extent of the work required (see Section 4).
Also check the vacuum readings under various
conditions (see Section 3).
Check the oil pressure with a gauge
installed in place of the oil pressure sender
unit (see illustrations)and compare it to this
Chapter’s Specifications. If it’s extremely low,
the bearings and/or oil pump are probably
worn out.
Loss of power, rough running, knocking or
metallic engine noises, excessive valve train
noise and high fuel consumption rates may
also point to the need for an overhaul,
especially if they’re all present at the same
time. If a complete tune-up doesn’t remedy
the situation, major mechanical work is the
only solution.An engine overhaul involves restoring the
internal parts to the specifications of a new
engine. During an overhaul, the piston rings
are replaced and the cylinder walls are
reconditioned (rebored and/or honed). If a
rebore is done by an automotive machine
workshop, new oversize pistons will also be
installed. The main bearings, big-end bearings
and camshaft bearings are generally replaced
with new ones and, if necessary, the
crankshaft may be reground to restore the
journals. Generally, the valves are serviced as
well, since they’re usually in less-than-perfect
condition at this point. While the engine is
being overhauled, other components, such as
the distributor, starter and alternator, can be
rebuilt as well. The end result should be a like
new engine that will give many trouble free
miles. Note:Critical cooling system
components such as the hoses, drivebelts,
thermostat and water pump should be
replaced with new parts when an engine is
overhauled. The radiator should be checked
carefully to ensure that it isn’t clogged or
leaking (see Chapter 3).If you purchase a
2.4a The oil pressure sender unit (arrowed)
is located in the right front corner of the
engine block, near the oil filter2.4b The oil pressure can be checked by
removing the sender unit and refitting a
pressure gauge in its place

rebuilt engine or short block, some rebuilders
will not warranty their engines unless the
radiator has been professionally flushed. Also,
we don’t recommend overhauling the oil
pump - always refit a new one when an engine
is rebuilt.
Before beginning the engine overhaul, read
through the entire procedure to familiarise
yourself with the scope and requirements of
the job. Overhauling an engine isn’t difficult,
but it is time-consuming. Plan on the vehicle
being tied up for a minimum of two weeks,
especially if parts must be taken to an
automotive machine workshop for repair or
reconditioning. Check on availability of parts
and make sure that any necessary special
tools and equipment are obtained in advance.
Most work can be done with typical hand
tools, although a number of precision
measuring tools are required for inspecting
parts to determine if they must be renewed.
Often an automotive machine workshop will
handle the inspection of parts and offer
advice concerning reconditioning and
renewal. Note:Always wait until the engine
has been completely dismantled and all
components, especially the engine block,
have been inspected before deciding what
service and repair operations must be
performed by an automotive machine
workshop. Since the engine block’s condition
will be the major factor to consider when
determining whether to overhaul the original
engine or buy a rebuilt one, never purchase
parts or have machine work done on other
components until the engine block has been
thoroughly inspected. As a general rule, time
is the primary cost of an overhaul, so it
doesn’t pay to refit worn or substandard
parts.
If it turns out that a number of major
components are beyond reconditioning, it
may be cost effective to buy a factory-rebuilt
engine from a Jaguar dealership.
As a final note, to ensure maximum life and
minimum trouble from a rebuilt engine,
everything must be assembled with care in a
spotlessly-clean environment.
3 Vacuum gauge
diagnostic checks
2
A vacuum gauge provides valuable
information about what is going on in the
engine at a low cost. You can check for worn
rings or cylinder walls, leaking cylinder head or
intake manifold gaskets, incorrect carburettor
adjustments, restricted exhaust, stuck or
burned valves, weak valve springs, improper
ignition or valve timing and ignition problems.
Unfortunately, vacuum gauge readings are
easy to misinterpret, so they should be used
with other tests to confirm the diagnosis.
Both the absolute readings and the rate of
needle movement are important for accurate
interpretation. Most gauges measure vacuumin inches of mercury (in-Hg). As vacuum
increases (or atmospheric pressure decreases),
the reading will decrease. Also, for every
1000 foot increase in elevation above sea level;
the gauge readings will decrease about one
inch of mercury.
Connect the vacuum gauge directly to
intake manifold vacuum, not to ported (above
the throttle plate) vacuum (see illustration).
Be sure no hoses are left disconnected during
the test or false readings will result.
Before you begin the test, allow the engine
to warm up completely. Block the wheels and
set the handbrake. With the transmission in
Park, start the engine and allow it to run at
normal idle speed.
Warning: Carefully inspect the
fan blades for cracks or damage
before starting the engine. Keep
your hands and the vacuum
tester clear of the fan and do not stand in
front of the vehicle or in line with the fan
when the engine is running.
Read the vacuum gauge; an average,
healthy engine should normally produce
between 17 and 22 inches of vacuum with a
fairly steady needle.
Refer to the following vacuum gauge
readings and what they indicate about the
engines condition:
1A low steady reading usually indicates a
leaking gasket between the intake manifold
and carburettor or throttle body, a leaky
vacuum hose, late ignition timing or incorrect
camshaft timing. Check ignition timing with a
timing light and eliminate all other possible
causes, utilising the tests provided in this
Chapter before you remove the timing belt
cover to check the timing marks.
2If the reading is three to eight inches below
normal and it fluctuates at that low reading,
suspect an intake manifold gasket leak at an
intake port or a faulty injector.
3If the needle has regular drops of about two
to four inches at a steady rate the valves are
probably leaking. Perform a compression or
leak-down test to confirm this.
4An irregular drop or down-flick of the
needle can be caused by a sticking valve or
an ignition misfire. Perform a compression or
leak-down test and read the spark plugs.5A rapid vibration of about four in-Hg
vibration at idle combined with exhaust
smoke indicates worn valve guides. Perform a
leak-down test to confirm this. If the rapid
vibration occurs with an increase in engine
speed, check for a leaking intake manifold
gasket or cylinder head gasket, weak valve
springs, burned valves or ignition misfire.
6A slight fluctuation, say one inch up and
down, may mean ignition problems. Check all
the usual tune-up items and, if necessary, run
the engine on an ignition analyser.
7If there is a large fluctuation, perform a
compression or leak-down test to look for a
weak or dead cylinder or a blown cylinder
head gasket.
8If the needle moves slowly through a wide
range, check for a clogged PCV system,
incorrect idle fuel mixture, throttle body or
intake manifold gasket leaks.
9Check for a slow return after revving the
engine by quickly snapping the throttle open
until the engine reaches about 2,500 rpm and
let it shut. Normally the reading should drop to
near zero, rise above normal idle reading
(about 5 in.-Hg over) and then return to the
previous idle reading. If the vacuum returns
slowly and doesn’t peak when the throttle is
snapped shut, the rings may be worn. If there
is a long delay, look for a restricted exhaust
system (often the silencer or catalytic
converter). An easy way to check this is to
temporarily disconnect the exhaust ahead of
the suspected part and redo the test.
4 Cylinder compression check
2
1A compression check will tell you what
mechanical condition the upper end (pistons,
rings, valves, cylinder head gasket) of your
engine is in. Specifically, it can tell you if the
compression is down due to leakage caused
by worn piston rings, defective valves and
seats or a blown cylinder head gasket. Note:
The engine must be at normal operating
temperature and the battery must be fully
charged for this check.
2Begin by cleaning the area around the
spark plugs before you remove them
(compressed air should be used, if available,
otherwise a small brush or even a bicycle tyre
pump will work). The idea is to prevent dirt
from getting into the cylinders as the
compression check is being done.
3Remove all of the spark plugs from the
engine (see Chapter 1).
4Block the throttle wide open.
5Detach the coil wire from the centre of the
distributor cap and ground it on the engine
block. Use a jumper wire with alligator clips on
each end to ensure a good earth. Also,
remove the fuel pump relay (see Chapter 4) to
disable the fuel pump during the compression
test.
Engine removal and overhaul procedures 2B•3
2B
3.4 The vacuum gauge is easily attached
to a port on the intake manifold, and can
tell a lot about an engine’s state of tune
3261 Jaguar XJ6

6Refit the compression gauge in the spark
plug hole (see illustration).
7Crank the engine over at least seven
compression strokes and watch the gauge.
The compression should build up quickly in a
healthy engine. Low compression on the first
stroke, followed by gradually increasing
pressure on successive strokes, indicates
worn piston rings. A low compression reading
on the first stroke, which doesn’t build up
during successive strokes, indicates leaking
valves or a blown cylinder head gasket (a
cracked cylinder head could also be the
cause). Deposits on the undersides of the
valve heads can also cause low compression.
Record the highest gauge reading obtained.
8Repeat the procedure for the remaining
cylinders and compare the results to this
Chapter’s Specifications.
9Add some engine oil (about three squirts
from a plunger-type oil can) to each cylinder,
through the spark plug hole, and repeat the
test.
10If the compression increases after the oil
is added, the piston rings are definitely worn.
If the compression doesn’t increase
significantly, the leakage is occurring at the
valves or cylinder head gasket. Leakage past
the valves may be caused by burned valve
seats and/or faces or warped, cracked or bent
valves.
11If two adjacent cylinders have equally low
compression, there’s a strong possibility that
the cylinder head gasket between them is
blown. The appearance of coolant in the
combustion chambers or the crankcase
would verify this condition.
12If one cylinder is 20 percent lower than the
others, and the engine has a slightly rough
idle, a worn exhaust lobe on the camshaft
could be the cause.
13If the compression is unusually high, the
combustion chambers are probably coated
with carbon deposits. If that’s the case, the
cylinder head(s) should be removed and
decarbonised.
14If compression is way down or varies
greatly between cylinders, it would be a goodidea to have a leak-down test performed by
an automotive repair workshop. This test will
pinpoint exactly where the leakage is
occurring and how severe it is.
5 Engine removal-
methods and precautions
If you’ve decided that an engine must be
removed for overhaul or major repair work,
several preliminary steps should be taken.
Locating a suitable place to work is
extremely important. Adequate work space,
along with storage space for the vehicle, will
be needed. If a workshop or garage isn’t
available, at the very least a flat, level, clean
work surface made of concrete or asphalt is
required.
Cleaning the engine compartment and
engine before beginning the removal
procedure will help keep tools clean and
organised.
An engine hoist or A-frame will also be
necessary. Make sure the equipment is rated
in excess of the combined weight of the
engine and transmission. Safety is of primary
importance, considering the potential hazards
involved in lifting the engine out of the vehicle.
If the engine is being removed by a novice,
a helper should be available. Advice and aid
from someone more experienced would also
be helpful. There are many instances when
one person cannot simultaneously perform all
of the operations required when lifting the
engine out of the vehicle.
Plan the operation ahead of time. Arrange
for or obtain all of the tools and equipment
you’ll need prior to beginning the job. Some of
the equipment necessary to perform engine
removal and refitting safely and with relative
ease are (in addition to an engine hoist) a
heavy duty trolley jack, complete sets of
spanners and sockets as described in the
front of this manual, wooden blocks and
plenty of rags and cleaning solvent for
mopping up spilled oil, coolant and petrol. If
the hoist must be rented, make sure that you
arrange for it in advance and perform all of the
operations possible without it beforehand.
This will save you money and time.
Plan for the vehicle to be out of use for
quite a while. A machine workshop will be
required to perform some of the work which
the do-it-yourselfer can’t accomplish without
special equipment. These shops often have a
busy schedule, so it would be a good idea to
consult them before removing the engine in
order to accurately estimate the amount of
time required to rebuild or repair components
that may need work.
Always be extremely careful when removing
and refitting the engine. Serious injury can
result from careless actions. Plan ahead, take
your time and a job of this nature, although
major, can be accomplished successfully.
6 Engine- removal and refitting
3
Note:Read through the entire Section before
beginning this procedure. It is recommended
to remove the engine and transmission from
the top as a unit, then separate the engine
from the transmission on the workshop floor. If
the transmission is not being serviced, it is
possible to leave the transmission in the
vehicle and remove the engine from the top by
itself, by removing the crankshaft damper and
tilting up the front end of the engine for
clearance,but access to the upper
bellhousing bolts is only practical when the
rear transmission mount and driveshaft have
been removed and the transmission is angled
down with a trolley jack.
Removal
1Relieve the fuel system pressure (see
Chapter 4).
2Disconnect the battery negative cable.
Caution: If the stereo in your vehicle is
equipped with an anti-theft system, make
sure you have the correct activation code
before disconnecting the battery.
3Place protective covers on the wings and
cowl and remove the bonnet (see Chapter 11).
4Remove the battery and battery tray.
5Remove the air cleaner assembly (see
Chapter 4).
6Raise the vehicle and support it securely on
axle stands. Drain the cooling system and
engine oil and remove the drivebelts (see
Chapter 1).
7Clearly label, then disconnect all vacuum
lines, coolant and emissions hoses, wiring
harness connectors and earth straps.
Masking tape and/or a touch up paint
applicator work well for marking items (see
illustration). Take instant photos or sketch
the locations of components and brackets.
8Remove the cooling fan(s) and radiator (see
Chapter 3).
9Disconnect the heater hoses.
10Release the residual fuel pressure in the
tank by removing the petrol cap, then detach
the fuel lines connecting the engine to the
chassis (see Chapter 4). Plug or cap all open
fittings.
2B•4 Engine removal and overhaul procedures
4.6 A compression gauge with a threaded
fitting for the spark plug hole is preferred
over the type that requires hand pressure
to maintain the seal - be sure to block
open the throttle valve as far as possible
during the compression check!
6.7 Label both ends of each wire and hose
before disconnecting it
3261 Jaguar XJ6