1997 JAGUAR XJ6 heating

3261 Jaguar XJ6
REPAIRS & OVERHAUL
Engine and associated systems
Engine in-car repair procedures Page 2A•1
Engine removal and overhaul procedures Page 2B•1
Cooling, heating and air conditioning systems Page 3•1
Fuel and exhaust systems Page 4•1
Engine electrical systems Page 5•1
Emissions and engine cone control systems Page 6•1
Transmission
Automatic transmissionPage 7•1
DrivetrainPage 8•1
Brakes and suspension
Braking systemPage 9•1
Suspension and steering systems Page 10•1
Body equipment
Bodywork and fittingsPage 11•1
Body electrical systems Page 12•1
Wiring diagramsPage 12•16
REFERENCE
Dimensions and weights Page REF•1
Jacking and vehicle support Page REF•1
Radio/cassette unit anti-theft system - precaution Page REF•1
Conversion factorsPage REF•2
Use of EnglishPage REF•3
Buying spare parts and vehicle identification Page REF•4
General repair procedures Page REF•5
Tools and working facilities Page REF•6
MOT test checksPage REF•8
Fault findingPage REF•12
Glossary of technical terms Page REF•18
IndexPage REF•22
Contents

3261 Jaguar XJ6
0•14Weekly checks
Tyre condition and pressure
It is very important that tyres are in good
condition, and at the correct pressure - having
a tyre failure at any speed is highly dangerous.
Tyre wear is influenced by driving style - harsh
braking and acceleration, or fast cornering,
will all produce more rapid tyre wear. As a
general rule, the front tyres wear out faster
than the rears. Interchanging the tyres from
front to rear ("rotating" the tyres) may result in
more even wear. However, if this is
completely effective, you may have the
expense of replacing all four tyres at once!
Remove any nails or stones embedded in the
tread before they penetrate the tyre to cause
deflation. If removal of a nail does reveal thatthe tyre has been punctured, refit the nail so
that its point of penetration is marked. Then
immediately change the wheel, and have the
tyre repaired by a tyre dealer.
Regularly check the tyres for damage in the
form of cuts or bulges, especially in the
sidewalls. Periodically remove the wheels,
and clean any dirt or mud from the inside and
outside surfaces. Examine the wheel rims for
signs of rusting, corrosion or other damage.
Light alloy wheels are easily damaged by
"kerbing" whilst parking; steel wheels may
also become dented or buckled. A new wheel
is very often the only way to overcome severe
damage.New tyres should be balanced when they are
fitted, but it may become necessary to re-
balance them as they wear, or if the balance
weights fitted to the wheel rim should fall off.
Unbalanced tyres will wear more quickly, as
will the steering and suspension components.
Wheel imbalance is normally signified by
vibration, particularly at a certain speed
(typically around 50 mph). If this vibration is
felt only through the steering, then it is likely
that just the front wheels need balancing. If,
however, the vibration is felt through the
whole car, the rear wheels could be out of
balance. Wheel balancing should be carried
out by a tyre dealer or garage.
Tread Depth - visual check
The original tyres have tread wear safety
bands (B), which will appear when the tread
depth reaches approximately 1.6 mm. The
band positions are indicated by a triangular
mark on the tyre sidewall (A).1Tread Depth - manual check
Alternatively, tread wear can be
monitored with a simple, inexpensive device
known as a tread depth indicator gauge.2Tyre Pressure Check
Check the tyre pressures regularly with
the tyres cold. Do not adjust the tyre
pressures immediately after the vehicle has
been used, or an inaccurate setting will result.3
Tyre tread wear patterns
Shoulder Wear
Underinflation (wear on both sides)
Under-inflation will cause overheating of the
tyre, because the tyre will flex too much, and
the tread will not sit correctly on the road
surface. This will cause a loss of grip and
excessive wear, not to mention the danger of
sudden tyre failure due to heat build-up.
Check and adjust pressures
Incorrect wheel camber (wear on one side)
Repair or renew suspension parts
Hard cornering
Reduce speed!
Centre Wear
Overinflation
Over-inflation will cause rapid wear of the
centre part of the tyre tread, coupled with
reduced grip, harsher ride, and the danger of
shock damage occurring in the tyre casing.
Check and adjust pressures
If you sometimes have to inflate your car’s
tyres to the higher pressures specified for
maximum load or sustained high speed, don’t
forget to reduce the pressures to normal
afterwards.
Uneven Wear
Front tyres may wear unevenly as a result of
wheel misalignment. Most tyre dealers and
garages can check and adjust the wheel
alignment (or "tracking") for a modest charge.
Incorrect camber or castor
Repair or renew suspension parts
Malfunctioning suspension
Repair or renew suspension parts
Unbalanced wheel
Balance tyres
Incorrect toe setting
Adjust front wheel alignment
Note: The feathered edge of the tread which
typifies toe wear is best checked by feel.

done during the engine overhaul. Note:If the
engine was severely overheated, the cylinder
head is probably warped (see paragraph 12).
Cleaning
2Scrape all traces of old gasket material and
sealing compound off the cylinder head
gasket, intake manifold and exhaust manifold
sealing surfaces. Be very careful not to gouge
the cylinder head. Special gasket-removal
solvents that soften gaskets and make
removal much easier are available at car
accessory outlets.
3Remove all built up scale from the coolant
passages.
4Run a stiff wire brush through the various
holes to remove deposits that may have
formed in them. If there are heavy deposits in
the water passages, the bare head should be
professionally cleaned at a machine
workshop.
5Run an appropriate-size tap into each of the
threaded holes to remove corrosion and
any thread sealant that may be present. If
compressed air is available, use it to clear the
holes of debris produced by this operation.
Warning: Wear eye protection
when using compressed air!
6Clean the exhaust and intake manifold stud
threads with a wire brush.
7Clean the cylinder head with solvent and dry
it thoroughly. Compressed air will speed the
drying process and ensure that all holes and
recessed areas are clean. Note:Decarbonising
chemicals are available and may prove very
useful when cleaning cylinder heads and valve
train components. They are very caustic and
should be used with caution. Be sure to follow
the instructions on the container.
8Clean the lifters with solvent and dry themthoroughly. Compressed air will speed the
drying process and can be used to clean out
the oil passages. Don’t mix them up during
cleaning - keep them in a box with numbered
compartments.
9Clean all the valve springs, spring seats,
keepers and retainers with solvent and dry
them thoroughly. Work on the components
from one valve at a time to avoid mixing up
the parts.
10Scrape off any heavy deposits that may
have formed on the valves, then use a
motorised wire brush to remove deposits from
the valve heads and stems. Again, make sure
that the valves don’t get mixed up.
Inspection
Note:Be sure to perform all of the following
inspection procedures before concluding that
machine workshop work is required. Make a
list of the items that need attention. The
inspection procedures for the lifters and
camshafts, can be found in Part A.
Cylinder head
11Inspect the cylinder head very carefully for
cracks, evidence of coolant leakage and other
damage. If cracks are found, check with an
automotive machine workshop concerning
repair. If repair isn’t possible, a new cylinder
head should be obtained.
12A common problem on aluminium engines
is erosion of the cylinder head or engine block
coolant passages due to improper sealing.
Using a new cylinder head gasket held
against the cylinder head, trace the bolt holes
and coolant passage outlines in pencil on the
cylinder head. Use the gasket to trace the
same on the top of the engine block (see
illustration). If the top of the engine block has
eroded outsideof the pattern around thewater passages or cylinder head bolt holes,
the engine block must be renewed; the
manufacturer doesn’t recommend resurfacing
it. If the cylinder head has eroded outside of
the water passage holes but the erosion is
away fromthe combustion chamber, the
eroded area can be built up with metal-
impregnated epoxy and machined flat again.
13Using a straightedge and feeler gauge,
check the cylinder head gasket mating
surface (on the engine block and cylinder
head) for warpage (see illustration). If the
warpage exceeds the limit found in this
Chapter’s Specifications, it can be resurfaced
at an automotive machine workshop, but no
more then 0.010-inch of material should be
removed. If the cylinder head had been
overheated, take it to the machinist for
inspection before proceeding further. It’s
possible that the overheating could have
annealed (softened) the aluminium of the
cylinder head, making it unsuitable for
machine work. In this case, a new cylinder
head is required.
Note 1:To check if a cylinder head has been
machined previously, measure the height
between the cylinder head gasket surface and
the valve cover mounting surface with a large
micrometer or vernier caliper and compare
with Specifications.
Note 2:Jaguar aluminium cylinder heads
require precision machine work. It is best to
find a machine workshop that has
considerable experience in servicing Jaguar
cylinder heads.
14Examine the valve seats in each of the
combustion chambers. If they’re pitted,
cracked or burned, the cylinder head will
require valve service that’s beyond the scope
of the home mechanic.
Engine removal and overhaul procedures 2B•7
2B
3261 Jaguar XJ6 10.12 Place the new head gasket on the engine block, and trace
around the water passages and bolt holes - make sure there is no
erosion of the aluminium beyond these lines
10.13 Check the cylinder head and engine block gasket surfaces
for warpage by trying to slip a feeler gauge under a precision
straightedge (see the Specifications for the maximum warpage
allowed and use a feeler gauge of that thickness) - check both the
cylinder head and engine block (shown)

2Using a gasket scraper, remove all traces of
gasket material from the engine block. Be very
careful not to nick or gouge the gasket sealing
surfaces.
3Remove the main bearing caps and
separate the bearing inserts from the caps
and the engine block. Tag the bearings,
indicating which cylinder they were removed
from and whether they were in the cap or the
engine block, then set them aside.
4Remove all of the threaded oil gallery plugs
from the engine block. The plugs are usually
very tight - they may have to be drilled out and
the holes retapped. Use new plugs when the
engine is reassembled.
5If the engine is extremely dirty, it should be
taken to an automotive machine workshop to
be steam cleaned or hot tanked.
6After the engine block is returned, clean all
oil holes and oil galleries one more time.
Brushes specifically designed for this purpose
are available at most car accessory outlets.
Flush the passages with warm water until the
water runs clear, dry the engine block
thoroughly and wipe all machined surfaces
with a light, rust preventive oil. If you have
access to compressed air, use it to speed the
drying process and to blow out all the oil
holes and galleries. Warning: Wear eye protection
when using compressed air!
7If the engine block isn’t extremely dirty or
sludged up, you can do an adequate cleaning
job with hot soapy water and a stiff brush.
Take plenty of time and do a thorough job.
Regardless of the cleaning method used, be
sure to clean all oil holes and galleries very
thoroughly, dry the engine block completely
and coat all machined surfaces with light oil.
8The threaded holes in the engine block
must be clean to ensure accurate torque
readings during reassembly. Run the proper
size tap into each of the holes to remove rust,
corrosion, thread sealant or sludge and
restore damaged threads (see illustration). If
possible, use compressed air to clear the
holes of debris produced by this operation.
9Refit the main bearing caps and tighten the
bolts finger tight.
10After coating the sealing surfaces of the
new core plugs with suitable sealant, refit
them in the engine block (see illustration).
Make sure they’re driven in straight and
seated properly or leakage could result.
Special tools are available for this purpose,
but a large socket, with an outside diameter
that will just slip into the core plug, a 1/2-inchdrive extension and a hammer will work just
as well.
11Apply non-hardening sealant (such as
Permatex no. 2 or Teflon pipe sealant) to the
new oil gallery plugs and thread them into the
holes in the engine block. Make sure they’re
tightened securely.
12If the engine isn’t going to be
reassembled right away, cover it with a large
plastic trash bag to keep it clean.
16 Engine block- inspection
2
1Before the engine block is inspected, it
should be cleaned as described in Section 15.
2Visually check the engine block for cracks,
rust and corrosion (see illustration 10.12).
Look for stripped threads in the threaded
holes. It’s also a good idea to have the engine
block checked for hidden cracks by an
automotive machine workshop that has the
special equipment to do this type of work,
especially if the vehicle had a history of
overheating or using coolant. If defects are
found, have the engine block repaired, if
possible, or renewed. If the top of the engine
block has been eroded by coolant leakage
and the erosion is near the cylinder bores, the
engine block must be renewed.
3Check the cylinder bores for scuffing and
scoring.
4Check the cylinders for taper and out-of-
round conditions as follows (see illustrations):
5Measure the diameter of each cylinder at
the top (just under the ridge area), centre and
bottom of the cylinder bore, parallel to the
crankshaft axis.
6Next, measure each cylinder’s diameter at
the same three locations perpendicular to the
crankshaft axis.
7The taper of each cylinder is the difference
between the bore diameter at the top of the
cylinder and the diameter at the bottom. The
out-of-round specification of the cylinder bore
Engine removal and overhaul procedures 2B•11
2B
16.4a Measure the diameter of each
cylinder at 90° to engine centreline (A), and
parallel to engine centreline (B) - out-of-
round is the difference between A and B;
taper is the difference between A and B at
the top of the cylinder and A and B at the
bottom of the cylinder16.4b The ability to “feel” when the
telescoping gauge is at the correct point
will be developed over time, so work
slowly and repeat the check until you’re
satisfied that the bore measurement is
accurate
3261 Jaguar XJ6
15.8 All bolt holes in the engine block -
particularly the main bearing cap and
cylinder head bolt holes - should be
cleaned and restored with a tap (remove
debris from holes after this is done)15.10 A large socket on an extension can
be used to drive the new core plugs into
the bores
16.4c The gauge is then measured with a
micrometer to determine the bore size

in the back sides of the ring grooves and the
oil hole in the lower end of each rod are clear.
6If the pistons and cylinder walls aren’t
damaged or worn excessively, and if the
engine block is not rebored, new pistons
won’t be necessary. Normal piston wear
appears as even vertical wear on the piston
thrust surfaces and slight looseness of the top
ring in its groove. New piston rings, however,
should always be used when an engine is
rebuilt.
7Carefully inspect each piston for cracks
around the skirt, at the pin bosses and at the
ring lands.
Caution: Some early 1988 3.6 litre engines
(before engine no. 9D 121113) have
incorrectly-stamped pistons. On these, the
word FRONT is actually stamped on the rear
of the pistons. Correct pistons will have the
cast arrows on the inside of the skirt to your
left when facing the word FRONT.
8Look for scoring and scuffing on the thrust
faces of the skirt, holes in the piston crown
and burned areas at the edge of the crown. If
the skirt is scored or scuffed, the engine may
have been suffering from overheating and/or
abnormal combustion, which caused
excessively high operating temperatures. The
cooling and lubrication systems should be
checked thoroughly. A hole in the piston
crown is an indication that abnormal
combustion (pre-ignition) was occurring.
Burned areas at the edge of the piston crown
are usually evidence of spark knock
(detonation). If any of the above problems
exist, the causes must be corrected or the
damage will occur again. The causes may
include intake air leaks, incorrect air/fuel
mixture, incorrect ignition timing and EGR
system malfunctions.
9Corrosion of the piston, in the form of small
pits, indicates that coolant is leaking into the
combustion chamber and/or the crankcase.
Again, the cause must be corrected or the
problem may persist in the rebuilt engine.
10Measure the piston ring groove clearance
by laying a new piston ring in each ring groove
and slipping a feeler gauge in beside it (see
illustration). Check the clearance at three or
four locations around each groove. Be sure touse the correct ring for each groove - they are
different. If the clearance is greater than that
listed in this Chapter’s Specifications, new
pistons will have to be used.
11Check the piston-to-bore clearance by
measuring the bore (see Section 16) and the
piston diameter. Make sure the pistons and
bores are correctly matched. Measure the
piston across the skirt, at a 90° angle to
the piston pin (see illustration). Subtract the
piston diameter from the bore diameter to
obtain the clearance. If it’s greater than
specified, the engine block will have to be
rebored and new pistons and rings installed.
12Check the piston-to-rod clearance by
twisting the piston and rod in opposite
directions. Any noticeable play indicates
excessive wear, which must be corrected.
13If the pistons must be removed from the
connecting rods for any reason, the rods
should be taken to an automotive machine
workshop, to be checked for bend and twist,
since automotive machine shops have special
equipment for this purpose.
14Check the connecting rods for cracks and
other damage. Temporarily remove the rod
caps, lift out the old bearing inserts, wipe the
connecting rod and cap bearing surfaces
clean and inspect them for nicks, gouges and
scratches. After checking the connecting
rods, renew the old bearings, slip the caps
into place and tighten the nuts finger tight.
Note:If the engine is being rebuilt because of
a connecting rod knock, be sure to refit new
rods.
19 Crankshaft- inspection
3
1Clean the crankshaft with solvent and dry it
with compressed air (if available). Be sure to
clean the oil holes with a stiff brush and flush
them with solvent.
2Check the main and connecting rod bearing
journals for uneven wear, scoring, pits and
cracks.
3Remove all burrs from the crankshaft oil
holes with a stone, file or scraper.4Check the remainder of the crankshaft for
cracks and other damage. It should be
magnafluxed to reveal hidden cracks - an
automotive machine workshop will handle the
procedure.
5Using a micrometer, measure the diameter
of the main and connecting rod journals and
compare the results to this Chapter’s
Specifications (see illustration). By
measuring the diameter at a number of points
around each journal’s circumference, you’ll be
able to determine whether or not the journal is
out-of-round. Take the measurement at each
end of the journal, near the crank throws, to
determine if the journal is tapered. Crankshaft
runout should be checked also, but large V-
blocks and a dial indicator are needed to do it
correctly. If you don’t have the equipment,
have a machine workshop check the runout.
6If the crankshaft journals are damaged,
tapered, out-of-round or worn beyond the
limits given in the Specifications, have the
crankshaft reground by an automotive
machine workshop. Be sure to use the correct
size bearing inserts if the crankshaft is
reconditioned.
7Check the oil seal journals at each end of
the crankshaft for wear and damage. If the
seal has worn a groove in the journal, or if it’s
nicked or scratched, the new seal may leak
when the engine is reassembled. In some
cases, an automotive machine workshop may
be able to repair the journal by pressing on a
thin sleeve. If repair isn’t feasible, a new or
different crankshaft should be installed.
8Refer to Section 20 and examine the main
and big-end bearing inserts.
20 Main and big-end bearings-
inspection and selection
3
Inspection
1Even though the main and big-end bearings
should be replaced with new ones during the
engine overhaul, the old bearings should be
retained for close examination, as they may
Engine removal and overhaul procedures 2B•13
2B
19.5 Measure the diameter of each
crankshaft journal at several points to
detect taper and out-of-round conditions
3261 Jaguar XJ6 18.10 Check the ring groove clearance
with a feeler gauge at several points
around the groove
18.11 Measure the piston diameter at a
90° angle to the piston pin, at the bottom
of the piston pin area - a precision caliper
may be used if a micrometer isn’t available

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
3
Chapter 3
Cooling, heating and air conditioning systems
General
Radiator cap pressure rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5 to 117.5 psi
Thermostat rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 to 207° F
Torque wrench settingsNm lbf ft
Coolant pipe to block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 to 28 16 to 21
Fan assembly-to-drive hub nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 to 28 16 to 21
Fan clutch-to-fan blade bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 to 28 16 to 21
Thermostat cover bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 to 28 16 to 21
Thermostat housing-to-block bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 to 28 16 to 21
Water pump bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 to 28 16 to 21 Air conditioning and heating system - check and maintenance . . . . 13
Air conditioning compressor - removal and refitting . . . . . . . . . . . . . 15
Air conditioning condenser - removal and refitting . . . . . . . . . . . . . . 16
Air conditioning evaporator and expansion valve - removal
and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Air conditioning receiver/drier - removal and refitting . . . . . . . . . . . . 14
Antifreeze/coolant - general information . . . . . . . . . . . . . . . . . . . . . . 2
Coolant level check . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Coolant temperature sender unit - check and renewal . . . . . . . . . . . .9
Cooling system check . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Cooling system draining, flushing and refilling . . . . . . . . See Chapter 1
Drivebelt check, adjustment and renewal . . . . . . . . . . . See Chapter 1
Engine cooling fans - check and renewal . . . . . . . . . . . . . . . . . . . . . 4Engine oil cooler - renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Heater and air conditioning blower motors -circuit check
and component renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Heater and air conditioning control assembly -
check, removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Heater core - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Radiator, expansion tank and coolant reservoir -
removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Thermostat - check and renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Underbonnet hose check and renewal . . . . . . . . . . . . . . See Chapter 1
Water pump - check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Water pump and pipes - renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3•1
Specifications Contents
Easy,suitable for
novice with little
experienceFairly easy,suitable
for beginner with
some experienceFairly difficult,
suitable for competent
DIY mechanic
Difficult,suitable for
experienced DIY
mechanicVery difficult,
suitable for expert DIY
or professional
Degrees of difficulty
54321
1 General information
Engine cooling system
All vehicles covered by this manual employ a
pressurised engine cooling system with
thermostatically-controlled coolant circulation.
An impeller type water pump mounted on the
front of the block pumps coolant through the
engine. The coolant flows around each cylinder
and toward the rear of the engine. Cast-in
coolant passages direct coolant around the
intake and exhaust ports, near the spark plug
areas and in proximity to the exhaust valve
guides.A wax-pellet type thermostat is located in
the thermostat housing at the front of the
engine. During warm up, the closed
thermostat prevents coolant from circulating
through the radiator. When the engine
reaches normal operating temperature, the
thermostat opens and allows hot coolant to
travel through the radiator, where it is cooled
before returning to the engine.
The cooling system is sealed by a pressure-
type radiator cap. This raises the boiling point
of the coolant, and the higher boiling point of
the coolant increases the cooling efficiency
of the radiator. If the system pressure exceeds
the cap pressure-relief value, the excess
pressure in the system forces the spring-
loaded valve inside the cap off its seat and
allows the coolant to escape through the
overflow tube into a coolant reservoir. Whenthe system cools, the excess coolant is
automatically drawn from the reservoir back
into the radiator. This type of cooling system is
known as a closed design because coolant
that escapes past the pressure cap is saved
and reused.
The Jaguar cooling system on 1988 and
1989 models has both a manifold tank and a
coolant recovery tank. The manifold tank is the
highest point in the cooling system and is the
location of the “radiator” cap (the cap is not on
the radiator). The recovery tank down in the
passenger’s footwell collects heated coolant
as described above. Models from 1990 to
1994 do not have a coolant recovery tank, but
have an enlarged manifold tank. In all models,
the recovery tank has a sensor in it to detect a
low coolant level, and the instrument panel has
a warning light to that effect.

Heating system
The heating system consists of two blower
fans, one under the dash on the right and one
on the left, and a heater core located within
the heater/air conditioning assembly which is
under the dash and behind the console.
Hoses connect the heater core to the engine
cooling system. Heater function is controlled
by the heater/air conditioning control head on
the dashboard. Hot engine coolant is
circulated through the heater core. When the
heater mode is activated, a flap door opens to
expose the heater box to the passenger
compartment. A fan switch on the control
head activates the blower motor, which forces
air through the core, heating the air.
Air conditioning system
The air conditioning system consists of a
condenser mounted in front of the radiator, an
evaporator mounted in the heat/air
conditioning assembly behind the console and
under the centre of the dash, a compressor
mounted on the engine, a filter-drier which
contains a high pressure relief valve and the
plumbing connecting all of the above.
A blower fan forces the warmer air of the
passenger compartment through the
evaporator core (sort of a radiator-in-reverse),
transferring the heat from the air to the
refrigerant. The liquid refrigerant boils off into
low pressure vapour, taking the heat with it
when it leaves the evaporator. The
compressor keeps refrigerant circulating
through the system, pumping the warmed
coolant through the condenser where it is
cooled and then circulated back to the
evaporator.
2 Antifreeze/coolant-
general information
Warning: Do not allow antifreeze
to come in contact with your
skin or painted surfaces of the
vehicle. Rinse off spills immediately withplenty of water. Antifreeze is highly toxic if
ingested. Never leave antifreeze lying
around in an open container or in puddles
on the floor; children and pets are
attracted by it’s sweet smell and may drink
it. Check with local authorities about
disposing of used antifreeze. Many
communities have collection centres which
will see that antifreeze is disposed of
safely. Never dump used antifreeze on the
ground or into drains.
Note:Non-toxic antifreeze is now
manufactured and available at local car
accessory outlets, but even these types
should be disposed of properly.
The cooling system should be filled with a
water/ethylene-glycol based antifreeze
solution, which will prevent freezing down to
at least -20° F, or lower if local climate
requires it. It also provides protection against
corrosion and increases the coolant boiling
point.
The cooling system should be drained,
flushed and refilled every 24,000 miles or
every two years (see Chapter 1). The use of
antifreeze solutions for periods of longer than
two years is likely to cause damage and
encourage the formation of rust and scale in
the system. If your tap water is “hard”, i.e.
contains a lot of dissolved minerals, use
distilled water with the antifreeze.
Before adding antifreeze to the system,
check all hose connections, because
antifreeze tends to leak through very minute
openings. Engines do not normally consume
coolant. Therefore, if the level goes down, find
the cause and correct it.
The exact mixture of antifreeze-to-water
you should use depends on the relative
weather conditions. The mixture should
contain at least 50-percent antifreeze, but
should never contain more than 70-percent
antifreeze. Consult the mixture ratio chart on
the antifreeze container before adding
coolant. Hydrometers are available at most
car accessory outlets to test the ratio
of antifreeze to water (see illustration). Use
antifreeze which meets the vehicle
manufacturer’s specifications.
3 Thermostat-
check and renewal
2
Warning: Do not attempt to
remove the radiator cap, coolant
or thermostat until the engine
has cooled completely.
Check
1Before assuming the thermostat is
responsible for a cooling system problem,
check the coolant level (Chapter 1), drivebelt
tension (Chapter 1) and temperature gauge (or
light) operation.
2If the engine takes a long time to warm up
(as indicated by the temperature gauge or
heater operation), the thermostat is probably
stuck open. Renew the thermostat.
3If the engine runs hot, use your hand to
check the temperature of the lower radiator
hose.
Warning: Do this check with the
engine off. Do not get your
hands near the fan blades. If the
hose is not hot, but the engine
is, the thermostat is probably stuck in the
closed position, preventing the coolant
inside the engine from travelling through
the radiator. Renew the thermostat. Do not
drive the vehicle without a thermostat. The
computer may stay in open loop and
emissions and fuel economy will suffer.
4If the lower radiator hose is hot, it means
that the coolant is flowing and the thermostat
is open. Consult the Troubleshootingsection
at the front of this manual for further diagnosis.
Renewal
5Disconnect 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.
6Drain the coolant from the radiator (see
Chapter 1).
7Remove the bolts from the thermostat
cover (see illustration). If the cover doesn’t
3•2 Cooling, heating and air conditioning systems
3261 Jaguar XJ6 2.4 An inexpensive hydrometer can be
used to test the condition of your coolant
3.7 Remove the two bolts (small arrows)
holding the thermostat cover to the
housing (large arrow)