1998 JAGUAR X308 engine coolant

6. Connec
t the oxygen sensor multiplugs.
Con

nect the plug(s) to the respective (previously noted)
sensor(s).
Cor
rectly position the multiplu
gs on the mounting bracket.

7. F
it the coolant header tank.
1. Reposition the tank and fit the securing nuts.
2. Connect the harness connector

8. R
efit the centre trim panel and th
e left hand enclosure panel to
the engine compartment.
1. Refit the centre trim panel.
2. Refit the left hand enclosure panel.
9. Raise the vehicle on the ramp.
10. Tighten the mounting brac ket securing bolts.

Exha
ust System - Catalyti
c Converter Gasket LH4. 0L NA V8 - AJ27/3.2L
NA V8 - AJ26
Re mo
val and Installation
Remova

l
1.
Op
en the engine compartment and fit paintwork protection
sheets.
2. Remove the front muffler; refer to Operation 30.10.18 in this
section.

3. Re
move the centre trim panel
from the engine compartment.
1. Remove the left hand side enclosure panel.
2. Remove the centre trim panel.

4. Repo
sition the expansion tank from the mounting.
1. Disconnect the coolant level sensor connector.
2. Remove the nuts which secures the tank.

5. CAUT
ION: Note the position of the upstream and
downstream (where fitted) o xygen sensor multiplugs for
reassembly.
Disconnect the oxygen sensor multiplugs.
Re
lease the multiplugs from th
e engine mounting bracket.

Dis
connect the plug(s) from the oxygen sensor(s)
6.
Re
move the four nuts which se
cure the downpipe catalytic
converter to the exhaust manifold.

5. Connec t
the oxygen sensor multiplugs.
Con
n
ect the plug(s) to the respective (previously noted)
sensor(s).
Cor r
ectly position the multiplu
gs on the mounting bracket.

6. Fi
t the coolant header tank.
1. Reposition the tank and fit the securing nuts.
2. Connect the harness connector

7. Re
fit the centre trim panel and th
e left hand enclosure panel to
the engine compartment.
1. Refit the centre trim panel.
2. Refit the left hand enclosure panel.
8. Raise the ramp.
9. Tighten the mounting brac ket securing bolts.

Exha
ust System - Cataly
tic Converter Gasket LH 4.0L SC V8 - AJ26
Remo
val and Installation
Remov
a
l
1.
Op
en the engine compartment and fit paintwork protection
sheets.

2. Re
move the centre trim panel
from the engine compartment.
1. Remove the left hand side enclosure panel.
2. Remove the centre trim panel.

3. Repo
sition the expansion tank from the mounting.
1. Disconnect the coolant level sensor connector.
2. Remove the nuts which secures the tank.

4. CAUT
ION: Note the position of the upstream and
downstream (where fitted) o xygen sensor multiplugs for
reassembly.
Disconnect the oxygen sensor multiplugs.
Di spl
ace the multiplugs from the engine mounting bracket.

Dis
connect the plug(s) from the oxygen sensor(s).

5.
Re
move the four nuts which se
cure the downpipe catalytic
converter to the exhaust manifold.

In
stallation
1.
Fit a ne
w gasket to the mani
fold mating flange on the
downpipe.

2. Fit
the downpipe catalytic converter.
1. Fit the downpipe assembly to the manifold.
Fit,
but do not fully tighten, the mounting bracket securing

bolts. (Leave loose until the nu ts securing the downpipe to
the exhaust manifold are fitted.)
3. Lower the ramp.

4. Tigh te
n the nuts securing the downpipe flange to the manifold
flange.

5. Connec t
the oxygen sensor multiplugs.
Con
n
ect the plug(s) to the respective (previously noted)
sensor(s).
Cor r
ectly position the multiplu
gs on the mounting bracket.

6. Fi
t the coolant header tank.
1. Reposition the tank and fit the securing nuts.
2. Connect the harness connector
7. Refit the centre trim panel and th e left hand enclosure panel to
the engine compartment.

Symp
tom #5
Sy
m
ptom #5


Low r
e
frigerant charge
*
Check f or 'hissi
ng' at expansion
valve; may be witnessed by low
HIGH side pressure. Recover / recharge
*
Moi
s
ture or air in the system
*
Chec k syst
em pressures
*
Heat er ci
rcuit air-lock
*
R e
fer section 303-03 for fill / bleed procedure
*
Suct ion
pipe touching bank 1 (A)
cylinder head (rubber isolator
missing)
*
Check the pi
pe cluster for correct fitti
ng
*
• NOTE: Electrical faults may be more rapidly traced using PDU
Sym
ptom
Possib
l
e Sources
Acti
o
n
Insuffi
ci
ent
heating
Coo l
ant flow valve stuck 'closed'
Coolant flow valve stuck 'open' allowing recirculation of
coolant at engine idle
*
*
Re
new v
alve
*
Motorized in-car aspirator sei zed
*R e
new aspirator
*
Coo l
air bypass damper stuck open

*
Re new,
check fault code #43

*
B l
ocked air inlet / pollen filter
*
Chec k / cl
ean / renew
*
B l
ower speed low
*
Check performance range
*
Low cool ant
level
*
Adjust as req u
ired (verify and correct
reason for loss)
*
Engine
t
hermostat faulty
*
Check engine r u
nning temperature
*
Heater water pump seized
*Chec k op
eration
*
Heater ma trix
blocked
*
Re new m
atrix
*
Heater circui t
air-lock
*
R e
fer section 303-03 for fill / bleed
procedure
*

Sym
p
tom #4
Sym
ptom #4
Sy
m
ptom
Possib
l
e Sources
Acti
o
n
No
i
sy
system
Loose or damaged compressor drive
belt
*Adjust or r
e
new
*
Loose compressor mountings
*Check f o
r damage, tighten to specification if OK
*
Compressor oil level l
ow
*
Look for evidence of l
eakag
e and rectify as required
*
Compressor internal dama ge
*Check f o
r debris, renew compressor and receiver drier
*
B l
ower motor noise
*
Re new m
otor (assuming no fan interference)
*
Excessive refrige rant charge
*Check f o
r vibration or 'thumping'
in high pressure line; may be
witnessed by high pressure on both HIGH and LOW sides.
Recover / recharge
*

Parts List
The heater circuit 'scavenges' coolant from the engine cooling system by mean s of an electric water pump. The water pump
has a protection circuit to inhibit operation when the coolant temperature is <16°C; this is to prevent possible damage to
the impeller due to the presence of coolant borne ice particles. Coolant is drawn from the en gine system through the water
valve inlet port into the heater matrix. The coolant passes thro ugh the bottom section of the heater matrix from left to right
filling the end tank of the matrix before returning through the top half of the ma trix and through the outlet ports of the
water valve and back into the engine cooling system.
Non return valves are located in the heat er bypass hose and the hose between the water pump and valve. These valves are
required to prevent coolant flowing in th e wrong direction at low engine speeds and restrict convected flow through the
heater after the engine is switched off.
When the exterior ambient temperature is > 0°C the refrigerat ion system automatically operates cooling and dehumidifying
incoming air before it is re -heated by the heater matrix.
Water Valve Assembly
Location
The water valve assembly is located above the water pump, in the engine compartmen t and is secured to the firewall by a
bracket. The valve operates by means of an electrical solenoid which oscillates the valve stem between the inlet and outlet
ports.
When in automatic mode, the water valve duty cycle is influenced by the following inputs to the A/CCM:
Outlet air temperature 'Air off' heater matrix temperature External ambient Coolant temperature
ItemPart NumberDescription
1—Assembly pump - water
2—Hose - from header tank
3—Hose / connector - return to engine
4—Hose - heater feed to matrix
5—Valve - non return (by-pass)
6—Hose / connector - feed from engine
7—Hose - heater return from matrix
8—Assembly valve - water
9—Valve - non return

Engine speed (valve closed with the engine not running) Demand (set) temperature In-car temperature sensor Solar sensor
Re-heating of the refrigerated air is contro lled by the time that the water valve is open (i.e. not energised) over a six secon d
interval. The duty cycle of the water valve, the time open / time closed, is controlled by the A/CCM.
Maximum heating demand will cause the water valve to be fu lly open (not energised) to allow maximum coolant flow
through the heater matrix.
At Maximum cooling, the water va lve will be fully closed (energised) to prevent hot (engine temperature) coolant entering
the heater circuit; the pump however will continue to circulate coolant through both the heater matrix and water valve
bypass.
The water valve defaults open when the ignition is OFF.
Under engine stall conditions, when ignition is ON, the water valve will be open.
Water Pump Assembly
Located in the same area as the water valve, the water pump continually circulates coolant through the heater matrix
except when the conditions below apply:
The engine coolant is below 16°C. The ignition is OFF. Under engine stall conditions, when ignition is ON. Control panel OFF
Non return valves
The heater bypass hose has a non-return valve, located between the engine feed and return hoses. The valve prevents the
water pump from recirculating coolant fro m the heater at low engine speeds.
The flow indicator arrow embossed on the valve bo dy MUST point towards the coolant header tank.
CAUTION: Coolant flow will be compromi sed if either valve is fitted incorrectly. Observe the correct direction.
A second non-return valve is located betw een the water pump and water valve. This valve prevents hot coolant from flowing
into the heater with the engine switched off. The flow indicator arrow MUST point towards the water pump.
Heater feed and return hoses
The heater feed and return hoses are connected to the engine feed and return hoses by 'Quick-Fit' connection unions. The
feed hose has a Norma R20 connector and the return hose a Norma push and seal connector. The coolant system bleed
joints have Cobra clamps. All remaining hose connections have spring band hose clamps.
The engine feed hose is connected to the engine bypass hous ing and the engine return hose is connected to the engine
water pump.
Clamp Identification