1995 LAND ROVER DISCOVERY Workshop Manual

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.

CRUISE CONTROL
9
REPAIR CRUISE CONTROL ECU - Tdi
Service repair no - 19.75.49
Remove
1.Remove 4 studs securing fascia left hand
closing panel.
2.Remove closing panel.
3.Remove nut securing ECU/relay bracket.
4.Lower bracket for access.
5.Remove bottom nut securing ECU to bracket.
6.Open glove box, align stops with cut-outs in
fascia panel and lower.
7.Move SRS harness aside.
8.Remove top nut securing ECU to bracket.
9.Disconnect ECU multiplug.
10.Remove ECU.
Refit
11.Reverse removal procedure. Ensure electrical
multiplug is securely reconnected.

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.

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.

Tdi
3
DESCRIPTION AND OPERATION
Viscous unit slipping (Engine at normal running
temperature)
1. Inner member (drive in fast)
2. Outer member (drive out slow)
3. Running clearance
4. Valve plate
5. Valve (closed)
6. Bi-metal
7. Fluid seals
8. Ball race
AFluid chamber
BFluid chamber
If the engine speed is increased the degree of slip will
also increase to limit the maximum fan speed.Hot conditions
When operating in high ambient temperatures or
when stationary in traffic, the bi-metel thermostat will
operate and open the valve port between chambers A
and B.
Opening the valve (as shown in RR3758M) allows the
fluid to circulate between the two members, causing
the unit to couple, thus increasing the fan speed and
cooling effect.
Viscous unit coupled (Hot running conditions)
Bi-metal expanded, valve (open)

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.

26COOLING SYSTEM
2
FAULT DIAGNOSIS ENGINE RUNS COLD
Before conducting any cooling system diagnosis:
See
Description and operation, Engine Cooling
1.Check operation of viscous unit.See
Description and operation, Viscous Fan
Is viscous unit operating correctly?
NO -
See Repair, Viscous Coupling, Fan
Blades, Pulley and Fan Cowl
YES - Continue.
2.Is thermostat correct type and operating?
See
Repair, Thermostat
If problem is not diagnosed: Continue.
3.Are the air conditioning fans operating
continuously?
YES -
See Electrical Trouble Shooting
Manual.
NO - Continue.
4.Is temperature sender and gauge giving
accurate readings? Substitute parts and
compare readings. If problem is not diagnosed
repeat tests, starting at 1.

Tdi
1
ADJUSTMENT COOLANT
Service repair no - 26.10.01
Draining
WARNING: Do not remove any caps or
plugs when the engine is hot. The cooling
system is pressurised and personal
scalding could result.
1.Remove expansion tank filler cap.
2.Disconnect bottom hose from radiator and allow
coolant to drain into a container. Ensure
container is clean if reusing coolant.
NOTE: When expansion tank has emptied,
remove thermostat housing plug to assist
drainage. Similarly when coolant level is
below top of radiator, remove radiator plug.
3.Reconnect hose after draining and tighten hose
clamp.
Refit
CAUTION: In order to expel ALL air from
the cooling system, follow the procedures
carefully.
NOTE: Refill procedure is slow but can be
accelerated by squeezing hoses to assist
removal of air from the system.
4.Add correct mix of coolant into expansion tank
until radiator is full (as seen through plug hole on
top of radiator).
See LUBRICANTS, FLUIDS
AND CAPACITIES, Information, Anti-Freeze
CAUTION: Take care to avoid excess
coolant spillage from radiator.
5.Fit radiator plug.
6.Continue adding coolant into expansion tank
until coolant appears in thermostat housing.
CAUTION: Take care to avoid excess
coolant spillage from thermostat housing.
7.Fit thermostat housing plug.
8.Check coolant in expansion tank is level with
indicator post. Add more coolant if necessary.
9.Start engine and run for 5 minutes.
10.Allow engine to cool, check coolant level in
expansion tank; top up to level indicator post if
necessary.
11.Fit expansion tank filler cap.