1998 JAGUAR X308 V8 supercharged

T
he cooling system for the supercharged engine is very similar
to the normally aspirated engine, but with the addition of a
water cooled, intake air charge cooling system. This comprises a radiator, an electrically operated water pump and two
charge air cooler assemblies (heat exchangers) - one for each bank. The system works independently, but is connected to the
main cooling system at the bottom hose to allow for therma l expansion and to help to prevent unwanted circulation.
The condenser for the air conditioning system fits between th e coolant main radiator and the charge air cooling system
radiator.
Cylinder Block Heater, Drain Location
ItemDe
scription
1Rad

iator - Intake Air Coolant
2Ele

ctrically Operated Coolant Pump
3Top Hose
4Charge Air Coo

lers -
Intake Air Cooling
5Fi
lling Point for Intake Air Cooling
6N

on-Return Valves - Heater
7Ele

ctrically Operated Coolant Pump
8Hea

ter Matrix
9Wate

r Valve - Heater Control
10EGR V

alve (when fitted)
11Thr

ottle Body
12Coolan

t Recovery Bottle
13H

eader/Expansion Tank
14Eng

ine Coolant Pump
15The

rmostat Housing
16Bottom

Hose
17Air Bleed

Pipes
18Rad

iator - Main Cooling System

A coola
nt outlet plastic pipe connects to the outlet port of ea
ch cylinder head to provide a common connection point for the
radiator top hose. It also incorporates the Engine Coolant Te mperature (ECT) sensor which provides a signal representing
coolant temperature at the cylinder heads. The outlet pipe has connections to supply the heater matrix and the bypass flow
to the thermostat housing. An in-groove ga sket, seals each of the outlet-to-cylinder head joints. An aluminium gasket seals
the ECT sensor to duct joint.
Coolant Outlet Duct - Supercharged

The coolant outlet duct on the supercharged engine performs exactly the same function as on the normally aspirated engine
and connects to the same ports on the engine. The main physical difference is that the thermostat housing has been
ItemDe
scription
1Bottom

Hose Connection
2The

rmostat Cover
3The

rmostat
4Coolan

t Outlet Duct
5B

reather Connection
6ECT Se

nsor
7Top Hose Conn

ection
8Bypa

ss to Water Pump
9Hea

ter Hose Connection

combin
ed with the outlet duct and consequently, there is no separate housin
g assembly fitted above the water pump, as used
on the normally aspirated engine. The illustration shows the outlet duct viewed from the engine.
Thermostat Housing

The plastic housing for the thermostat is fitted between th e two cylinder banks immediately above the coolant pump.
Controlling the coolant flow through the radiator, the thermostat starts to open at 80 ° to 84 °C and is fully open at 96 °C.
A duct in the cylinder block connects the thermostat housing outlet to the coolant pump inlet. The joint between the
thermostat housing and the cylinder block is via an in-groove seal.
An air bleed outlet vents an y air in the system into the expansion reservoir, durin
g normal operation. A removable cap (usin g
a hex key) allows air to vent from the system when filling from empty.
On supercharged engines, the thermostat housin g is combined with the coolant outlet duct.
Radiator

The cooling
pack incorporates the radiator a
ssembly with integral transmission oil cool er (located in the radiator outlet tank),
an air conditioning condenser, and the cooling fans and cowl assembly.
The cooling pack on supercharged vehicles is the same as described above, but with the addition of a charge air cooler
coolant radiator located in front of the condenser.
Radiator Mounti
ng/Retention
T
he radiator is mounted on four rubber mounts, one on each
end of the upper and lower horizontal face. The two lower
mountings are supported on two isolated brackets mounted on the body; the lower cradle assembly has subsequently been
deleted.
A closing panel made from polypropylene, which retains the radiat or assembly, fits over the top of the radiator and is bolted
to the vehicle top panel.
Coolant Hoses - Engine

Engine Cooling - Cooling System Draining and Vacuum Filling
Gene
ral Procedures
WARNING: To avoid having scalding ho t coolant or steam blowing out of the cooling system, use extreme care when
removing the coolant pressure cap from a hot cooling system. Wait until the engine has cooled, then wrap a thick cloth
around the coolant pressure cap and turn it slowly until the pressure begins to release. Step ba ck while the pressure is
released from the system. When certain al l the pressure has been released (still with a cloth) turn and remove the coolant
pressure cap from the coolant expansion tank. Failure to fo llow these instructions may result in personal injury.
• CAUTIONS:
The engine cooling syst em must be maintained with the correct concentration and type of anti-freeze solution to
prevent corrosion and frost damage. Failure to follow th is instruction may result in damage to the vehicle.
Engine coolant will damage the paint finished surfaces. If spilt, immediately remove the coolant and clean the area
with water.
• NOTE: Vehicles fitted with supercharged engines shown, V8 NA engines similar.
All vehicles
1. Set
the heater controls to maximum HOT.

2. WARN
ING: Relieve the cooling system pressure by
unscrewing the coolant pressure cap. Failure to follow this
instruction may result in personal injury.
Remove the coolant expans ion tank pressure cap.
3. Raise a
nd support the vehicle.

4. NOTE : Remov
e and discard the
radiator drain plug seal.
Drain the coolant into a suitable container.
Remove the radiato
r drain plug.
5. CAUTION: Do not over tighten the drain plug. Failure to
follow this instruction may result in damage to the vehicle.
• NOTE: Install a new radiator drain plug seal.
Install the coolant drain plug.

Engine Cooling - Coolant Expansi
on Tank
Re
moval and Installation
Remov

al
1.
O
pen the engine compartment and fit paintwork protection
sheets.

2. R
emove the centre trim panel
from the engine compartment.
1. Remove the left hand side enclosure panel.
2. Remove the centre trim panel.
3. Ensure that the cooling system is cool and very carefully,
remove the pressure cap.
4. Place a cloth under the expansion tank to absorb any spillage
caused by disconnecting the hoses.

5. R
elease the hoses (Quick Fit connections) from the expansion
tank.
1. Release the hose, expansion tank to thermostat housing (coolant outlet pipe on supercharged
engines).
2. Release the hose, expansion tank to recovery tank.
3. Release the hose, expansion tank to radiator..
6. Fit blanking plugs to the pipes and the tank.

7. Re
move the expansion tank from the mounting.
1. Disconnect the coolant level sensor connector.
2. Remove the nuts which secures the tank.
8. Remove the expansion tank from the vehicle.
1. Use a pipe clamp to clam p the bottom hose branch.
2. Release the pipe clip an d move it along the pipe.
3. Disconnect the tank from the bottom hose and

Fuel D
istribution
Fuel is supplied to th
e engine
via eight fuel injectors (one pe r cylinder). The injectors are located in two fuel rails which r un
the length of each cylinder bank and ar e integral with the air intake manifold.
Fuel pumped from the tank enters a feed pipe at the rear of bank 2. Fuel flow is along bank 2 fuel rail, across the top front
of the engine (cross-over pipe) and through bank 1 fuel rail, the unused fuel re turning to the tank via a pressure regulator.
The fuel injectors are each controlled electrically from the engine control module (ECM).
A test valve is fitted to the cross-over pipe connecting the fu el rails at the front of the intake manifold. This valve allows the
fuel system to be depr essurized during servicin g and troubleshooting.
Fuel Injector

Eight, side-fed, dual straight-jet fuel injectors are fi tted in the fuel rails.
The injector consists of a solenoid, core, needle valve and ho using. When a control signal from the ECM is applied to the
solenoid coil, the needle valve lifts up and fuel is injected under pressure into the intake port. The fuel sprays from the
injectors are directed onto the back of the intake valves.
The injection quantity is determined by the length of time that the ECM signal is applied to the solenoid coil.
The injectors installed in the fuel rails of supercharged engines are of a higher flow rating than those installed in normally
aspirated engines and are secured in position by spring clips. Seals are instal led between the injector mounts of the fuel
rails and the related re cesses in the charge air cooler adaptors.
Pressure Regulator

Pa
rts List
The pressure regulator is a diap hragm-operated valve that regula tes fuel-rail pressure at 3,0 bar above the intake manifold
pressure. A pipe connects the throttle induction elbow to the pressure regulator to provide the vacuum control signal. On
supercharged engines, the pressure regulator vacuum feed is taken from the top of the supercharger outlet duct.
The regulator is fitted between the rear end of the right-hand fuel rail (bank 1) and the fuel return line to the tank.
Circuit Diagram, Fuel Injection Syst em - Normally Aspirated Vehicles

Ite
m
Par
t
Number
De
scr
iption
1—F
u
el Return
2—F
u
el Pressure Regulator
3—Inta
k
e Manifold Pressure