JAGUAR XJ6 1994 2.G Repair Manual

4.1.5 FAULT DIAGNOSIS
4.1.5.1 Introduction
The following diagnostic procedures are provided to assist properly qualified persons to identify and rectify the faults
in the system which are most likely to be encountered. Reference is made to the Electrical Diagnostic Manual (EDM),
which should be consulted for all electrical faults. When investigating faults relating to temperature, the prevailing
ambient temperature conditions should be taken into account. The climate control system is dealt with in Section 14.
Possible Cause
Thermostat stuck closed
Incorrect thermostat rating
Faulty temperature gauge
Faulty temperature transmitter
4.1.5.2 Diagnostic Procedures
Check
Test thermostat
Check thermostat operating
temperature
Refer to EDM
Refer to EDM
Symptom
herheating
Cooling fan(s) not operating 3verheating at
dle
roo cold
Refer to EDM
Incorrect thermostat rating
Thermostat not fitted
Cooling
fan(s) operating con-
tinuously Faulty temperature gauge
Faulty temperature transmitter
Radiator
core blocked
Radiator grille obstructed
Check thermostat operating
temperature
Remove thermostat housing
and inspect
Refer to EDM
Refer to EDM
Refer to EDM
Concentration of
anti
-freeze too high
Drive belt slack
Drive belt broken
Water pump seized
Insufficient coolant
Internally collapsed hoses
Incorrect ignition timing
Fuel
/ air mixture too weak
Incorrect valve
timing
Cylinder head gasket leaking
Brakes binding Check
for
hotspots in radiator
Check grille for obstruction
Check strength of coolant
Check belt tension
Visual check
Slacken drive belt and turn
water
pump pulley by hand.
Check belt for damage
Check coolant level
Pressure test system and
check for deformation of hoses
Refer to EDM
Refer to EDM
Check valve
timing
Pressure-test system. (Check
for contamination of coolant
in header tank)
Check brake calipers for stick
-
ing pistons and seized brake
pad pins
Thermostat stuck open
I Test thermostat
Remedy
Renew thermostat
Renew thermostat
Renew gauge
Renew transmitter
Flush
or renew radiator
Remove obstruction from
grille
Drain and fill
with coolant of
correct concentration
Adjust belt to correct tension
or renew belt
if worn
Renew belt
Renew water pump. Renew
drive belt
if required
Top-up coolant
Renew hoses as required
Rectify
as required
Rectify
as required
Correct valve
timing
Renew head gasket
Rectify
as required
Rectify
as required
Renew thermostat
Renew thermostat
Fit thermostat
Rectify
as required
Renew gauge
Renew transmitter
0
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0
0
Issue 1 August 1994 X300 VSM

Diagnostic Procedures (continued)
Symptom
Loss of cool-
Possible Cause Check
Loose clips on hoses
Hoses perished Visual check
Radiator core leaking Pressure
-test system
Water
pump seal leaking Pressure-test system
Thermostat gasket leaking Pressure
-test system. (Check
for distortion of thermostat
housing)
Inspect cap or test cap spring
pressure
Pressure
-test system. Check
strength of coolant
Pressure
-test system. Check
for contamination of coolant
and engine lubrication system
Identify
component(s)
contamination of engine
lubrication system)
Check
clips for correct
tight-
ness
Header tank cap defective
Porosity
in castings Pressure-test system
Corrosion caused by con
-
centration of anti-freeze being
too low
Cylinder head gasket leaking
Cracked or damaged internal
engine component affected. (Check for
Remedy
Tighten clips as required
Renew hoses as required
Repair or renew radiator
Renew water
pump
Renew gasket. Renew hous-
ing if required
Renew cap
Rectify as required
Rectify as required. Drain and
fill with coolant of correct con-
centration
Renew head gasket
Rectify as required

8

SECTION CON TENTS
Subsection Titie SRO Page
it0 IV ............ Preliminarypages .................................................................... i
4.2.1 ............. Cooling System Description ........................................................... 1
4.2.1.1 ........... Cooling System Description. Major Components .......................................... 1
4.2.1.2 ........... Cooling System Description. Components for Climate Control System ........................ 1
4.2.1.3 ........... Cooling System Description. Operation .................................................. 1
4.2.2 ............. Cooling System Configuration .......................................................... 2
4.2.3
............. Service Procedures ................................................................... 3
4.2.3.1
........... Service Procedures. Safety Precautions .................................................. 3
4.2.3.2
........... Service Procedures. Working Practices .................................................. 3
4.2.3.3
........... Service Procedures. Coolant Change .................................................... 3
4.2.4
............. Drain and Fill Procedures ............................................................. 4
4.2.4.1
........... Drain and Fill Procedures. Radiator, Drain ............................................... 4
4.2.4.2
........... Drain and Fill Procedures. Radiator, Fill ................................................. 4
* 4.2.4.3 ........... Drain and Fill Procedures. Complete System. Fill .......................................... 4
4.2.4.4
........... Drain and Fill Procedures. System. Air Bleeding ........................................... 4
4.2.5
............. Fault Diagnosis ...................................................................... 5
4.2.5.1
........... Fault Diagnosis. introduction ........................................................... 5
4.2.5.2
........... Fault Diagnosis. Diagnostic Procedures .................................................. 5
X300 VSM i Issue 1 August 1994

Lower radiator cradle to body
Radiator drain plug
1,5-2,5
Radiator temperature switch 13-17
Receiver drier to cooling fan assembly
Top radiator panel to body 7
-1 0
2,5-3,5
7-10
111. SERVICE
MATERIALS
Description USeS Notes
I to be issued I I I
0
SERVICE TOOLS & EQUIPMENT
No Jaguar service tools are required for working on the cooling system. Some normal workshop items will be required,
including a pressure tester, hydrometer and thermometer.
TORQUE TIGHTEN/ NG SPECI FICA TIONS
Fixing Tightening Torque
(Nm)
Electric fan assembly to body
Header tank bracket to body 7-10
7-10
Header tank to body
2,5-3,5
Hose clip, bleed hoses except those shown below 13-2.5
Hose clip, all main hoses 2,5-3,5
Hose clip, bleed hoses to header tank
Locator, fan cowl to radiator top panel 2.5-3,5
8,5-11,5
0
0
/U SERVICE
DATA
I Application
I Engine thermostat temperature rating
I Coolant header cap pressure rating
Water
pump / air injection pump drive belt tension
Drive belt tension measuring point
Specification I
88OC I
1.2 bar
Burroughs method: new belt 650
N. In service, if
tension falls below 320 N reset at 400 N
Clavis method: new belt 169 to 175 Hz. In service, if
tension falls below 127 Hz reset at 132 to 138 Hz.
Mid
-way between crankshaft and air injection pump
pulleys
X300 VSM Issue 1 August 1994 ii

Cooling System (V12
4.2.1 COOLING SYSTEM DESCRIPTION I
4.2.1.1 Major Components
o Engine crossflow radiator, incorporating a concentric tube cooler for the power steering fluid mounted in the
left
-hand radiator side tank. Vehicles with automatic transmission have a six-plate transmission fluid cooler
mounted in the right
-hand radiator side tank. A double-action temperature switch, for controlling the electric
radiator cooling fans, is mounted in the left
-hand radiator side tank.
0 Engine driven, viscous-coupled, radiator cooling fan
0 Two electrically operated radiator cooling fans, mounted in front of the radiator.
o Coolant circulating pump, belt driven from the engine crankshaft.
0 Coolant header tank with pressure relief cap and coolant level probe.
0 Two engine thermostats, one in each cylinder bank.
4.2.1.2
0 Heater matrix.
0 Electrically operated coolant circulating pump, mounted on the left-hand side of the engine bulkhead.
o Solenoid operated valve, located adjacent to the coolant circulating pump.
Components for Climate Control System
1
4.2.1.3 Operation
The configuration of the cooling system is shown in Sub-section 4.2.2.
The cooling system is pressurized, which allows the system to operate at a higher temperature without overheating.
The header tank is fitted with a pressure relief cap to protect the system against overpressure.
Under cold start conditions, coolant is forced by the engine driven water pump through each cylinder block and cylin
- der head to the thermostat housings. The thermostats are closed to give rapid engine warm up, hence the coolant is
returned via the engine cross pipe to the water pump inlet. When normal engine operating temperature is reached,
the thermostats open and coolant is diverted through the radiator before returning to the water pump inlet.
If the engine driven fan is unable to provide sufficient cooling, the electrically operated fans operate in series and paral
-
lel underthe control of the radiator mounted temperature switch. Under hot operating conditions, the electric fans may
continue to operate after the engine has been switched off. The fans stop automatically when the coolant temperature
has been reduced sufficiently.
The system also provides the coolant supply for the climate control system, which is described in Section 14.
I
I X300 VSM 1 Issue 1 August 1994

Cooling System (VI 2)
0
4.2.2 COOLING SYSTEM CONFIGURATION
Theconfigurationofthecooling system isshown in Fig. 1. Themaincoolantflows,withthesystem at normaloperating
temperature (i.e. with the engine thermostats open), are indicated
by arrows.
6 rr
1
2
1. Header Tank 3. Water Pump 5. Engine 7. Heater Pump
2. Radiator 4. Thermostat 6. Heater 8. Heater Valve
Fig.
1 Cooling System Layout
Issue 1 August 1994 2 X300 VSM

WARNING: DO NOT REMOVE THE HEADER TANK PRESSURE CAP WHILE THE ENGINE IS HOT. IF THE CAP MUST
BE REMOVED, PROTECT THE HANDS AGAINST ESCAPING STEAM AND SLOWLY TURN THE CAP ANTI- CLOCKWISE UNTIL THE EXCESS PRESSURE CAN ESCAPE. LEAVE THE CAP IN THIS POSITION UNTIL
ALL THE STEAM AND PRESSURE HAS ESCAPED AND THEN REMOVE THE CAP COMPLETELY.
WARNING: WHEN DRAINING THE COOLANT WITH THE ENGINE HOT, PROTECT THE HANDS AGAINST CONTACT
WITH HOT COOLANT.
WARNING
: WHEN WORKING WITHIN THE ENGINE COMPARTMENT, KEEP CLEAR OF THE ENGINE DRIVEN RADI- ATOR COOLING FAN WHEN THE ENGINE IS RUNNING.
4.2.3.2 Working Practices
Whenfilling thesystem with coolant,ensurethatthevehicle isstanding on a level surfaceand thatthecoolant is poured
in slowly so that airlocks are not introduced into the system. Airlocks can seriously affect the operation of the climate
control system and can cause damage to the heater circuit pump.
Hose clips should always be positioned
so that there is proper access for tightening and that the clip does not foul or
interfere with the operation of any components.
4.2.3 SERVICE PROCEDURES
4.2.3.1 Safety Precautions
The anti-freeze specified in Appendix A1 must be used wherever possible. It is designed to afford the maximum cor- rosion protection to all metals found in the engine cooling system, as well as having the frost protection properties
necessary during the winter months. Should it not be available, then anti-freeze conforming to Ford Motor Company
specification
ESBM97B49-A may be used. To provide optimum temperature and corrosion protection, the specified
anti-freeze concentration must always be used. Once coolant has been drained from the system, it must be discarded
and not reused. Anti-freeze is harmful to the environment. Always dispose of used coolant safely and never pour it down a drain connected to the public sewer.
CAUTION: Never fill or topup the system with water only.
CAUTION
: Anti-freeze is harmful to paintwork. Coolant spillages must be wiped up immediately and the affected
area washed to remove all traces of coolant.
CAUTION: To prevent the possibility of damage to the heater circuit
pump, the pump should be electrically isolated if the ignition has to be turned ON while the cooling system is drained.
The drive belt must always be tensioned to the specified value and the tension checked at the correct point on the belt.
This information is given in Sub-section IV in the preliminary pages.
When tightening components, the torque figures given in Sub
-section II in the preliminary pages should always be
used for the fastenings listed.
When fitting a replacement thermostat, ensure that the jiggle-pin is to the top of the thermostat housing.
4.2.3.3 Coolant Change
The coolant must be changed at intervals of four years. The system should be drained from the radiator drain plug,
flushed and filled with fresh coolant. Flushing should be carried out thoroughly to remove all the old coolant from the
engine and heater matrix. (The heatervalve isopen with the ignition OFF). AfterfilIing,checkthecoolant concentration
with a hydrometer. For specified anti-freeze and coolant concentration, see in Appendix Al.
X300 VSM 3 Issue 1 August 1994

€3 Cooling System (V12)
4.2.4 DRAIN AND FILL PROCEDURES
4.2.4.1 Radiator, Drain
. Place a drain tray in position under the radiator drain plug
. Remove the headertank pressure cap. Release thecaptive
Tighten the radiator drain plug.
(Fig.
1).
radiator drain
plug and drain the coolant.
CAUTION: This procedure does not drain the heater cir- cuit.
m: DO NOT REMOVE THE HEADER TANK PRES- SURE CAP WHILE THE ENGINE IS HOT. IF THE
CAP MUST BE REMOVED, PROTECT THE
HANDS AGAINST ESCAPING STEAM AND
SLOWLY TURN THE CAP
ANTI-CLOCKWISE UNTIL THE EXCESS PRESSURE CAN ESCAPE.
LEAVE THE CAP IN THIS POSITION UNTIL ALL
THE STEAM AND PRESSURE HAS ESCAPED
AND THEN REMOVE THE CAP COMPLETELY.
WARNING: WHEN DRAINING THE COOLANT
WITH THE
ENGINE HOT, PROTECT ME HANDS AGAINST
CONTACT WITH HOT COOLANT.
Fig. 1
4.2.4.2 Radiator, Fill
. Add coolant until the level in the header tank is steady at MAX. (Do not fit the header tank cap).
. Switch on the ignition. (The climate control system must be OFF).
. Start the engine and add coolant to the header tank if required to ensure that it does not empty.
. Run the engine until thetemperature gauge reads normal. (The enginespeed may be raised to reduce warm uptime).
. Switch off the ignition and wait for one minute.
Check that the coolant level in the header tank is between MAX and
10 mm above MAX. Add coolant as necessary.
. Fit the header tank cap.
4.2.4.3 Complete System, Fill
. Add coolant until the level in the header tank is steady at MAX. (Do not fit the header tank cap).
= Switch on the ignition. (The climate control system must be OFF).
. Start the engine and add coolant to the header tank if required to ensure that it does not empty.
. Run the engine until the temperature gauge reads normal, (The engine speed may be raised to reduce the warm up
. Turn the climate control system ON. Set the temperature to HI. Manually select a fan speed of approximately 50%.
. Run the engine for four minutes. Ensure that the climate control system outlet air temperature is hot to very hot and
that there is no noise from the heater coolant circulating pump. (The engine speed may be raised to assist with heat- ing).
time).
8 Switch
off the ignition and wait for one minute.
. Check that the coolant level in the header tank is between MAX and 10 mm above MAX. Add coolant as necessary.
. Fit the header tank cap.
4.2.4.4 System, Air Bleeding
After filling the system with coolant, any air present must be purged before effective cooling is possible. Provided the
correct fill procedure has been followed, purging of the system takes place automatically as follows:
The air entrained by the coolant, rises to the top of the radiator and to the highest point on each side of the engine (the
thermostat housings). While the thermostats are closed, the radiator is under reduced pressure due to the pump suc
- tion and air is bled through the jiggle-pins in each thermostat. Purged air is returnedvia the bleed system to the header
tank. When normal operating temperature is reached, the thermostats open and the system operates normally. ~~
Issue 1 August 1994 4 X300 VSM

4.2.5.2 Diagnostic Procedures
1
I Symptom ..
Overheating
herheating at
dle
roo cold ~~~
Possible Cause
Thermostat(s) stuck
closed
Incorrect thermostat rating
Faulty temperature gauge
Faulty temperature transmitter
Radiator core blocked
Radiator grille obstructed
Concentration of anti
-freeze
too high
Drive belt slack
Drive belt broken
Water pump seized
lnsuff icient coolant
Internally collapsed hoses
Incorrect ignition timing
Fuel
/ air mixture too weak
Incorrect valve timing
Cylinder head
gasket(s) leak-
ing
Brakes binding
Electric cooling
fan(s) not op- erating
Thermostat(s) stuck open
Incorrect thermostat rating
Thermostatb) not fitted
Electric cooling
fan(s) operat-
ing continuously
Faulty temperature gauge
Faulty temperature transmitter
Check
Cooling System (V12)
4.2.5 FAULT DIAGNOSIS
4.2.5.1 Introduction
The following diagnostic procedures are provided to assist properly qualified persons to identify and rectify the faults in the system which are most likely to be encountered. Reference is made to the Electrical Diagnostic Manual (EDM), which should be consulted for all electrical faults. When investigating faults relating to temperature, the prevailing
ambient temperature conditions should be taken into account. The climate control system is dealt with in Section 14.
Test thermostat(s)
Check thermostat operating
temperature
Refer to EDM
Refer to EDM
Check for
hotspots in radiator
Check grille for obstruction
Check strength of coolant
Check belt tension
Visual check Slacken drive belt and turn
water pump pulley by hand.
Check belt for damage
Check coolant level
Pressure test system and
check for deformation of hoses
Refer to EDM
Refer to EDM
Check valve timing
Pressure
-test system. (Check
for contamination of coolant in
header tank)
Check brake calipers for stick
- ing pistons and seized brake
pad pins
..
Refer to EDM
Test
thermostat(4
Check thermostat operating
temperature
Remove thermostat housing
and inspect
Refer to EDM
Refer to EDM
Refer to EDM
Remedy
Renew thermostat(s)
Renew thermostat(s1
Renew gauge
Renew transmitter
Flush or renew radiator
Remove obstruction from
grille
Drain and
fill with coolant of
correct concentration
Adjust belt to correct tension
or renew belt
if worn
Renew belt
Renew water pump. Renew
drive belt
if required
Top
-up coolant
Renew hoses as required
Rectify as required
Rectify as required
Correct valve timing
Renew head
gasket(s)
Rectify as required
Rectify as required
Renew
thermostat(s1
Renew thermostatb)
Fit thermostat(s)
Rectify as required
Renew gauge
Renew transmitter
Issue 1 August 1994 X300 VSM 5