1996 LAND ROVER DEFENDER coolant

COOLING SYSTEM
3
DESCRIPTION AND OPERATION COOLANT CIRCULATION
Operation
When the engine is started from cold the thermostat
(2) prevents coolant circulation through the radiator by
closing off the top hose (6). During the engine warm
up period the water pump (5) circulates coolant to the
cylinders in the crankcase and through separate ports
to the cylinder head. At the rear of the cylinder head a
proportion of the flow is diverted through a heater feed
pipe (16) to the matrix of the heater unit (15). The
coolant is then carried, via a heater return rail (14) and
hoses (7), back to the water pump. The remaining
coolant flows through a by-pass hose (9) at the
thermostat housing and back to the water pump to
complete the first cycle.
When the normal engine running temperature is
reached, the thermostat opens, closing off the by-pass
hose (9). Coolant is then circulated via the top hose
(6) and through the radiator, where it is cooled and
drawn from the radiator bottom hose (3) by the water
pump (5). The coolant circulation through the
crankcase and cylinder head remains the same.
Two bleed pipes (10) and (11) help control the system
pressure by purging excess air and coolant to the
expansion tank via the 'Y'piece ejector (12).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 by means of 'silicone fluid'.
1.Input (drive) member
2.Output (driven) member
3.Sensing mechanism (bi-metal coil)
The fan drive has to be engaged only periodically,
between 5% and 10%, during normal operating
conditions, because the engine is cooled by ram air
for most of the time.

COOLING SYSTEM
1
ADJUSTMENT DRAIN AND REFILL COOLING SYSTEM
Service repair no - 26.10.01
Draining
WARNING: DO NOT remove 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.Position a clean container under radiator if
coolant is to be reused.
3.Disconnect radiator bottom hose and allow
coolant to drain.
NOTE: A chassis undertray may be fitted
on some vehicle derivatives to conform to
legal requirements. When under chassis
remove and refit procedures are required, it may
be necessary to remove the undertray and/or
integral access panels.
See CHASSIS AND BODY,
Repair, Front undertray
orSee CHASSIS AND
BODY, Repair, Rear undertray
4.When expansion tank has emptied remove
thermostat housing plug to assist drainage.
5.Similarly when coolant is below top of radiator,
remove radiator plug.
6.Fit radiator bottom hose and fully tighten hose
clip.Refill
CAUTION: It is important that the correct
procedure is followed when refilling or
topping up the cooling system to avoid
trapping air in the system.
7.Fill cooling system with 50% - 50% of
water/anti-freeze mixture
See LUBRICANTS,
FLUIDS AND CAPACITIES, Information,
Recommended lubricants and fluids
8.Fill through expansion tank until radiator is full,
with level in expansion tank the same as
radiator.
NOTE: Care should be taken to avoid
excess coolant spillage.
9.Fit plastic plug in radiator.
10.Add a further 1 litre (1.76 pints) of coolant into
expansion tank and allow to settle.
11.Refit expansion tank cap and thermostat
housing plug.
12.Run engine at idle speed for 5 minutes.
13.Switch off engine and allow to cool.
14.Check that coolant in expansion tank is level
with top of indicator post. Top up if necessary.

26COOLING SYSTEM
2
REPAIR FAN COWL
Service repair no - 26.25.11
Remove
1.Disconnect battery.
2.Drain coolant.
See Adjustment, Drain and
refill cooling system.
3.Slacken retaining clips and remove radiator top
hose.
4.Slacken retaining clip and remove top hose from
intercooler.
NOTE: On vehicles fitted with EGR system,
remove complete intercooler top hose
assembly.
5.Remove viscous coupling and fan
See Viscous coupling and fan.
6.Remove 2 nuts securing top of fan cowl.
7.Release expansion tank hose from clips at base
of fan cowl.
8.Lift and remove cowl .
NOTE: On vehicles fitted with air
conditioning, it will be necessary to
remove the cowl and viscous fan unit
together to enable clearance of the compressor.Refit
9.Position fan cowl.
10.Fit viscous fan unit.
See Viscous coupling
and fan
11.Fit expansion tank hose into fan cowl clips.
12.Secure top of fan cowl to radiator top cover.
13.Fit intercooler top hose.
14.Fit radiator top hose.
15.Refill cooling system.
See Adjustment, Drain
and refill cooling system
16.Reconnect battery.
FAN PULLEY
Service repair no - 26.25.04.
Remove
1.Disconnect battery.
2.Remove viscous fan unit.
See Viscous
coupling and fan
3.Remove drive belt.See ELECTRICAL, Repair,
Auxiliary drive belt
4.Unscrew 4 bolts and remove pulley from adaptor
boss.
Refit
5.Fit fan pulley to adaptor boss. Tighten bolts to
25
Nm (18 lbf/ft).
6.Fit drive belt.See ELECTRICAL, Repair,
Auxiliary drive belt
7.Fit viscous fan unit.See Viscous coupling
and fan
8.Reconnect battery.

COOLING SYSTEM
5
REPAIR 28.Secure steering pump and bracket to auxiliary
mounting bracket.
29.Fit steering pump pulley.
30.Fit drive belt
See ELECTRICAL, Repair,
Auxiliary drive belt
.
31.Fit fan cowl
See Fan cowl.
32.Fit viscous fan unit
See Viscous coupling and
fan
.
33.Fit intercooler top hose.
34.Fit radiator top hose.
35.Refill cooling system.
See Adjustment, Drain
and refill cooling system
36.Reconnect battery.THERMOSTAT
Service repair no - 26.45.01
Remove
1.Partially drain cooling system, until coolant level
is below thermostat housing.
2.Disconnect top hose from outlet elbow.
3.Disconnect electrical connections to water
temperature switch.
4.Unscrew 2 bolts and remove outlet elbow.
5.Withdraw thermostat. Note 88°C rating of
thermostat.
6.Place thermostat in a container half full of water.
Heat water and observe temperature at which
thermostat begins to open. Thermostat is
satisfactory if it opens between 85°-89°C.
Refit
7.Fit thermostat with jiggle pin/vent hole upwards.
8.Secure outlet elbow to thermostat housing.
Tighten bolts to
25 Nm (18 lbf/ft).
9.Fit water temperature switch connections.
10.Fit top hose to outlet elbow.
11.Refill cooling system.
See Adjustment, Drain
and refill cooling system

COOLING SYSTEM
7
REPAIR EXPANSION TANK
Service repair no - 26.15.01
Remove
1.Position container to collect coolant spillage.
2.Slacken retaining clips and disconnect both
hoses from base of expansion tank.
3.Remove 3 bolts securing expansion tank to
inside wing and mounting bracket.
4.Remove expansion tank.
Refit
5.Fit expansion tank to inside wing and mounting
bracket.
6.Fit both hoses to base of tank.
7.Check and top up cooling system
See
SECTION 10, Maintenance, Under bonnet
maintenance

AIR CONDITIONING
1
DESCRIPTION AND OPERATION AIR CONDITIONING SYSTEM
Description
Air conditioning is an optional system which provides
fully integrated climate control for the vehicle interior.
The air conditioning system comprises four major
units as follows:- An evaporator matrix and expansion
valve (1), housed in the heater/ cooler unit (3), an
engine mounted compressor (4), a condenser (5),mounted in front of the radiator, and a receiver/drier
(7) located to the right of the condenser.
Ancillary components in the system comprise a blower
motor (2), also housed in the heater/cooler unit, and
condenser cooling fan motors (6), mounted on a
support frame. The four major units are interconnectd
by preformed metal and flexible refrigerant pipes as
illustrated below (RH drive installation shown).
Coolant flow to a heater matrix, housed in the heater
cooler unit, is controlled by a water valve (8) from a
combined air conditioning panel on the vehicle fascia.
1.Evaporator matrix and expansion valve
2.Blower motor
3.Heater/cooler unit
4.Compressor
5.Condenser6.Condenser fan motors
7.Receiver/drier
8.Water valve
9.Heater matrix feed and return hoses

ELECTRICAL
3
DESCRIPTION AND OPERATION Door and bonnet switches
Perimetric protection for the vehicle is provided by
ECU inputs connected to the starter switch, bonnet
switch and door switches.
Ultrasonic sensor
The ultrasonic sensor operates by emitting an air
pressure carrier wave which is subsequently received
by the sensor as it bounces back from objects inside
the vehicle. Once armed, the alarm will sound if wave
is disturbed by a door opening, or if movement is
detected inside the vehicle.
When the volumetric sensor is activated it monitors
movement within the vehicle for 15 seconds before
detecting and responding to intrusions. If the sensor
detects movement it delays arming until a quiet period
has lapsed; if continuous movement is detected, the
alarm will not arm volumetrically.
NOTE: Interior protection will not operate
until 15 seconds after alarm is set.
The ultrasonic sensor is positioned in a different
location, according to vehicle type, as follows:
·90/110 Station Wagon - RH cantrail trim
·90/110 Pick-up - On headlining, between interior
lamp and rear view mirror
·130 Crewcab - On headlining above RH door
Alarm sounder
Two types of alarm sounder can be fitted, one with a
battery back-up facility and or without battery back-up,
both providing an audible warning whenever the alarm
is triggered. The vehicle horn will also operate if the
alarm sounds.
The alarm sounder is fitted to LH inner front wing in
the engine compartment.
NOTE: Disconnecting the battery on
vehicles fitted with the battery backed-up
facility will result in the alarm sounding, if
correct procedure has not been followed.Engine immobilisation warning light
The engine immobilisation warning light is located on
the instrument panel, and provides a visual indication
that the engine is immobilised.
Anti-theft alarm indicator light
The anti-theft alarm indicator light is located on the
instrument panel, between the fuel and coolant
temperature indicators, and provides a visual
indication of the alarm/ immobiliser status.