Page 338 of 873
CRUISE CONTROL
1
REPAIR BRAKE AND CLUTCH PEDAL SWITCHES/VENT
VALVES
Service repair no - 19.75.34 - Clutch Switch
Service repair no - 19.75.35 - Brake Switch
Remove
1.Remove 3 studs securing driver's side fascia
closing panel.
2.Release and move closing panel aside.
3.Locate and release locking sleeve.
4.Release switch/vent valve from pedal bracket.
5.Disconnect vacuum hose and harness connector
from switch.
6.Remove switch.
Refit
7.Reverse removal procedure.
NOTE: Ensure locking sleeve is correctly
positioned.
Page 344 of 873

CRUISE CONTROL
7
REPAIR CRUISE CONTROL ECU - V8i
Service repair no - 19.75.49
Remove
1.Remove lower dash panel.
2.Disconnect ECU multi-plug.
3.Remove ECU fixing.
4.Remove ECU.
5.Reverse removal procedure. Ensuring that
electrical multi-plug is securely reconnected.
SPEED TRIP ECU - MANUAL V8i
NOTE: The neutral lock out relay
module/speed trip ECU is mounted in the
right hand side footwell. To identify
components.
See Electrical Trouble Shooting
Manual.
VEHICLE SPEED SENSOR
Service repair no - 18.30.22
For Tdi
See FUEL SYSTEM Tdi, Repair, Vehicle
Speed Sensor
For V8iSee FUEL SYSTEM MFI, Repair, Vehicle
Speed Sensor
NEUTRAL LOCK OUT RELAY
Service repair no - 19.75.28
1.Remove 3 studs securing fascia right hand side
closing panel.
2.Release and move closing panel aside.
3.Remove 2 studs securing right hand side 'A' post
lower trim casing.
4.Remove casing.
5.Locate relay (neutral coloured base) and release
base from bracket.
6.Remove relay.
NOTE: For further information.See
Electrical Trouble Shooting Manual.
Refit
7.Reverse removal procedure.
Page 345 of 873

19FUEL SYSTEM
8
REPAIR ACTUATOR - Tdi
Service repair no - 19.75.05
NOTE: The actuator is non serviceable, fit
a new unit if failure or damage occurs.
Remove
1.Disconnect battery negative lead.
2.Remove split pin, withdraw clevis pin and
disconnect cable from lever.
3.Disconnect link ball end from cable lever.
4.Disconnect vacuum hose from actuator.
5.Remove nut securing actuator to bracket and
remove actuator.
6.Inspect rubber diaphragm. Fit a new actuator
assembly if diaphragm is damaged.Refit
7.Check that link setting distance (dimension 'A')
equals 16 mm and that the retainer is locked in
position. If correct, proceed to paragraph 9.
8.If dimension 'A' is not correct, proceed as
follows:
·Measure 16 mm from diaphragm collar and
mark the position.
·Position link and retainer to the mark and
rotate retainer half a turn to secure.
·Check measurement 'A' is still 16 mm, then
turn retainer a further quarter turn to lock.
9.Fit actuator and secure to bracket with nut.
10.Connect vacuum hose.
11.Connect link ball end to cable lever.
12.Connect cable to lever and secure with clevis pin
and split pin.
13.Adjust cable position to remove any free play
from link, setting dimension 'B' should be 103
mm.
Page 347 of 873

Tdi
1
DESCRIPTION AND OPERATION ENGINE COOLING
Description
The Tdi engine uses a pressurized cooling system
and cross flow radiator which is supplied from a
separate header tank. The radiator assembly is in
three sections. The largest section is for engine
coolant and the other two sections which are cast in
aluminium, are the engine oil cooler and the turbo
charger intercooler.
A belt driven viscous fan and centrifugal water pump
is located in the front of the cylinder block. Hot coolant
is supplied to the heater through hoses. Two small
diameter air purge hoses connect the top of the
radiator and cylinder head water gallery, to the header
tank.
Coolant circulation (engine cold)
1. Cross flow radiator
2. Header tank
3. Viscous fan
4. Heater hoses
5. By pass hose and engine thermostat
6. Air purge hoses
7. Coolant pumpCOOLANT CIRCULATION
Operation
When the engine is started from cold the thermostat
prevents any coolant circulation through the radiator
by closing off the top hose. During the engine warm
up period, the water pump, pumps coolant towards
the rear of the cylinder block around each of the
cylinders. Coolant as it is heated rises through ports in
the cylinder block and head gasket, into the cylinder
head.The coolant flows forwards to the thermostat,
by-pass port and radiator top hose connection.
Start from cold (thermostat closed)
While the thermostat is closed, coolant circulates
around the cylinder block and cylinder head via the
by-pass.
Engine warm (thermostat open)
When the engine reaches normal running temperature
the thermostat closes off the by-pass and opens the
flow to the top of the radiator.
Page 348 of 873

26COOLING SYSTEM
2
DESCRIPTION AND OPERATION VISCOUS FAN
Description
The viscous drive unit for the engine cooling fan,
provides a means of controlling the speed of the fan
relative to the running temperature of the engine. The
viscous unit is a type of fluid coupling, which drives
the fan blades through the medium of a special
'silicone fluid' injected into the unit during
manufacture.
1. Drive in from water pump spindle
2. Drive out to fan blades
3. Bi-metalOperation
The viscous unit consists of two principal components:
An inner member 1 which is secured to water pump
spindle and is driven by the fan belt.
An outer member 2 which has the fan blades
attached, houses the working parts and is driven
through the medium of the viscous fluid.
The inner and outer members have interlocking
annular grooves machined in each, with a small
running clearance 3 to allow the silicone fluid to
circulate through the valve plate 4.
The unit also contains a valve 5 which is controlled by
an external bi-metal thermostat 6.
Starting engine from cold
During the time the engine is at rest the silicone fluid
drains down, half filling chambers A and B. Thus when
the engine is first started sufficient fluid is present in
chamber A to provide a positive drive between the
members, as is evident by the initial noise of the fan.
However within a very short period of time, after
starting the engine, the fan speed and noise will
decline indicating that the fluid is being centrifuged
into chamber B (as seen in RR3757M) causing the
drive to slip.
Page 350 of 873

Tdi
1
FAULT DIAGNOSIS ENGINE OVERHEATING
Before conducting any cooling system diagnosis:
See
Description and operation, Engine Cooling
1.Is coolant level correct?
NO - Allow engine to cool, top up level to
expansion tank seam.
YES - Continue.
2.Is drive belt tension correct?
NO -
See ENGINE, Repair, Compressor
Drive Belt
YES - Continue.
3.Is coolant in radiator frozen?
YES - Slowly thaw and drain system.
See
Adjustment, Coolant
NO - Continue.
4.Is air flow through radiator restricted or blocked?
YES - Apply air pressure from engine side of
radiator to clear obstruction.
NO - Continue.
5.Are there any external leaks, from water pump,
engine gaskets, fast idle thermostat or the heater
unit?
YES - Investigate and rectify.
See Adjustment,
Coolant
NO - Continue.
6.Are fan blades fitted correct way round, concave
side towards engine?
NO - Rectify.
YES - Continue
7.Is viscous unit operating correctly?
See
Description and operation, Viscous Fan
NO - Renew.See Repair, Viscous
Coupling, Fan Blades, Pulley and Fan
Cowl
YES - Carry out a pressure test on radiator cap
and system. Check thermostat type,
operation and correct fitting.
See Repair,
Thermostat
If pressure test leads you to suspect coolant
leakage across gaskets, go to check 10,
otherwise: Continue.8.Are the air conditioning fans operating correctly?
See Electrical Trouble Shooting Manual.
NO - Rectify.
YES - Continue.
9.Is temperature sender and gauge giving
accurate readings?
NO - Sustitute parts and compare readings.
YES - Continue.
10.Carry out cylinder pressure test to determine if
pressure is leaking into cooling system causing
over pressurising and loss of coolant.
If problem is not diagnosed, check the coolant system
for engine oil contamination and engine lubrication
system for coolant contamination.
If only the coolant system is contaminated suspect a
cylinder head gasket.
If both systems are contaminated, suspect the
radiator.
If only the lubrication system is contaminated with
coolant, suspect leakage past cylinder liner seals or
cylinder head gasket.
Page 353 of 873

Tdi
1
REPAIR VISCOUS COUPLING, FAN BLADES, PULLEY AND
FAN COWL
Service repair no - 26.25.03/05
Viscous coupling -Remove1to3
Fan blades -Remove1to4
Fan cowl -Remove1to3
Fan pulley -Remove1to6
Remove
WARNING: Disconnect battery negative
terminal to prevent engine being started
before removing or adjusting drive belt.
1.Slacken nut securing viscous coupling/fan blade
assembly to pulley.
NOTE: Nut securing viscous unit to pulley
has a left hand thread. Release by turning
clockwise when viewed from front of
viscous unit.
2.Drop viscous unit and fan assembly into bottom
of cowling
3.Remove two fixings clips from top of cowling and
lift cowling complete with viscous unit and fan
out of lower mountings.
4.Remove fan blades from viscous coupling if
necessary.
5.Remove serpentine drive belt and, if fitted, air
conditioning compressor belt.
6.Remove pulley fixings, remove pulley.
NOTE: The serpentine belt is removed by
using a hexagonal socket and tommy bar
on the auto-tensioning pulley nut. Whilst
tensioning the device the belt can be removed.
7.Reverse removal procedure. Ensure fan blades
are fitted correctly. Fan is marked 'front' and
should be fitted with word 'front' closest to
radiator. Tighten to
30 Nm.
8.Refit drive belt.See ENGINE, Repair, Drive
Belt
THERMOSTAT
Service repair no - 26.45.01
Remove
1.Partially drain cooling system, until coolant level
is below thermostat housing.
2.Disconnect hose from thermostat housing.
3.Disconnect electrical connections to water
temperature switch.
4.Remove outlet elbow.
5.Withdraw thermostat.
Test
6.Note rating of thermostat is 88°C. Place
thermostat in a container half full of water. Heat
water, observe temperature at which thermostat
begins to open. Thermostat is satisfactory if its
open between 85°C and 89°C.
Refit
7.Insert thermostat with jiggle pin/vent hole upper
most (12 o'clock position) .
8.Fit the outlet elbow and new joint washer.
Tighten to
28 Nm.
9.Reverse removal procedure. 1 to 3.
10.Check for coolant leaks around all connections
and joint faces.
Page 356 of 873

26COOLING SYSTEM
2
DESCRIPTION AND OPERATION COOLANT CIRCULATION
Operation
When the engine is started from cold the thermostat
prevents any coolant circulation through the radiator
by closing off the top hose. During the engine warm
up period, the water pump, pumps coolant around the
cylinders to the rear of the cylinder block along the
main galleries in both cylinder banks. At the rear of
the cylinder block the coolant rises through a large
port in each cylinder head/block joint face, and then
flows forward to connect with ports at the front of the
inlet manifold. From the manifold the coolant is carried
by an external pipe to the heater unit and from the
heater through another external pipe to the pump
inlet.The coolant circulation through the cylinder block and
heads, does not change when normal running
temperature is reached and the thermostat opens. But
with the thermostat open, coolant flows through the
top hose to the radiator where it is cooled and drawn
back into the pump via the bottom hose.