oil temperature LAND ROVER DEFENDER 1996 User Guide

26COOLING SYSTEM
4
DESCRIPTION AND OPERATION Operation
To engage and disengage the fan drive the bi-metal
coil senses air temperature behind the radiator. When
a pre-determined temperature is reached, the coil
opens a valve (5) which allows fluid to enter the drive
area and, due to centrifugal force, circulates to the
annular drive area.
There are two sets of annular grooves (3), one in the
drive clutch and the other in the drive body, a specific
clearance being provided between the two sets of
grooves.
Viscous unit disengaged (engine at normal
running temperature)
1.Input (drive) member
2.Output (driven) member
3.Running clearance
4.Pump plate
5.Valve (closed)
6.Sensing mechanism (bi-metal coil)
7.Fluid seal
8.Bearing, input member
9.Fluid chamber
10.Fluid reservoirWhen this clearance is filled with viscous fluid, a
shearing action, caused by the speed differential
between the two drive components, transmits torque
to the fan. The fluid is thrown to the outside of the unit
by centrifugal force from where it is recirculated to the
reservoir (10) via the pump plate (4) adjacent to the
drive member.
If the engine speed is increased the amount of slip will
also increase to limit the maximum fan speed.
When the air temperature from the radiator drops
sufficiently, the bi-metal coil closes the valve and
prevents fluid entering the drive area. The fluid that is
in the drive area will gradually pump out into the
reservoir (10) and the fan will return to an idle
condition.
Viscous unit engaged (hot running temperature)
Bi-metal coil (6) expanded, valve (5) open.

CLUTCH
1
FAULT DIAGNOSIS CLUTCH ASSEMBLY CONDITIONS
For the clutch to operate correctly it is important the
following conditions are satisfied:-
·The primary shaft (15) must be free in the
crankshaft spigot bush (17).
·The friction plate (2) must be able to slide easily on
the splines on the primary shaft (15), to a position
where it does not contact either the flywheel or the
pressure plate.
·The friction plate must not be distorted or the
linings contaminated with oil, which may cause it to
stick or continue to run in contact with the flywheel
or pressure plate.
A number of faults can develop in the operation of the
clutch for a variety of reasons and most faults are due
to normal wear at high mileage. Problems can also
occur if the unit has been renewed by an unskilled
operator.
Recognising and diagnosing a particular clutch fault is
therefore of paramount importance in ensuring that
the problem is rectified at the first attempt.
Problems which develop in the clutch are as follows:-
·Clutch spin/drag
·Clutch slip
·Clutch judder/fierceCLUTCH SPIN - DRAG
Symptoms
Clutch spin is that, with engine running and clutch
pedal depressed, the gears cannot be immediately
engaged without making a grinding noise. This
indicates the clutch is not making a clean break.
However, if the clutch pedal is held depressed for
several seconds the friction plate will eventually break
free from the engine and the gear will engage silently.
Clutch spin as it becomes more severe develops into
clutch drag, making the silent engagement of a gear
impossible, regardless of how long the pedal is held
depressed.
CLUTCH SLIP
Symptoms
Clutch slip is most evident climbing a hill or when the
vehicle is moving off from stationary with a heavy
load. As the clutch is released, slip occurs between
the engine and the transmission, allowing the engine
speed to increase without a corresponding increase in
vehicle speed.
Clutch slip can develop to the stage where no power
is transmitted through the clutch as the pedal is
released.
CLUTCH JUDDER - FIERCE
Symptoms
Clutch judder or fierce engagement, like slip, is most
likely to occur when the vehicle is moving off from
stationary. As the clutch pedal is released the vehicle
will move rapidly or in a series of jerks, which cannot
be controlled even by careful operation of the clutch
by the driver.
It should be noted that a vehicle may display all the
symptoms or any combination of the symptoms
described, depending on the driving conditions vehicle
load and operating temperatures.

57STEERING
4
DESCRIPTION AND OPERATION Rotary valve misaligned
Demand for assistance (Valve misaligned)
When the steering wheel and input shaft is turned,
steering resistance transmitted to the worm causes
the torsion bar to be twisted and the valve ports to be
misaligned for a right or left turn. The misalignment of
the valve ports directs all fluid pressure A to one side
of the piston only and allows displaced fluid B on the
other side.
When demanding maximum assistance, any
excessive fluid output from the pump due to high
pump speed, will circulate through the regulator valve
located in the pump unit, causing the temperature of
the fluid and the pump to rise rapidly.CAUTION: To avoid excessive fluid
temperatures which could damage the oil
seals, the steering must not be held on full
lock for more than 30 seconds in one minute.
Only when the steering wheel, and the demand for
assistance, is released, will the torsion bar return the
valve to neutral, allowing the fluid to circulate through
the reservoir where it is cooled.
In the unlikely event of mechanical failure of the
torsion bar, a coarse splined connection (7) between
the input shaft and worm, ensures steering control is
maintained sufficient to allow the vehicle to be
recovered.

82AIR CONDITIONING
2
DESCRIPTION AND OPERATION Operation
Evaporator unit and expansion valve
High pressure liquid refrigerant is delivered to the
expansion valve which is the controlling device for the
air conditioning system. A severe pressure drop
occurs across the valve and as the refrigerant flows
through the evaporator it picks up heat from the
ambient air, boils and vaporizes. As this change of
state occurs, a large amount of latent heat is
absorbed. The evaporator is therefore cooled and as
a result heat is extracted from the air flowing across
the evaporator. The refrigerant leaves the evaporator,
on its way to the compressor, as a low pressure gas.
An evaporator sensor measures the air temperature at
the evaporator and engages or disengages the
compressor clutch to prevent icing of the air ways.
Compressor
The compressor, a pump specially designed to raise
the pressure of the refrigerant, is mounted on the front
of the engine and is driven by an independent drive
belt from the crankshaft pulley. The compressor draws
vaporized refrigerant from the evaporator. It is
compressed with a resulting rise in temperature and
passed on to the condenser as a hot, high pressure
vapour.
Condenser
The condenser is mounted directly in front of the
radiator and consists of a refrigerant coil mounted in a
series of thin cooling fins to provide the maximum
heat transfer. Air flow across the condenser is induced
by vehicle movement and assisted by two electric fans
attached to the frame of the condenser. The
refrigerant high pressure vapour enters the condenser
inlet on the RH side. As the vapour passes through
the condenser coils the air flow, assisted by the two
fans, carries the latent heat away from the condenser.
This induces a change of state resulting in the
refrigerant condensing into a high pressure warm
liquid. From the condenser, the refrigerant continues
to the receiver/ drier.
Receiver/drier
This component acts as a reservoir and is used to
hold extra refrigerant until it is needed by the
evaporator. The drier within the receiver unit contains
a filter and dessicant (drying material) which absorb
moisture and prevent dessicant dust from being
carried with the refrigerant into the system.AIR CONDITIONING AND HEATER CONTROLS -
LH DRIVE
1. Temperature control
Move the lever upwards (RED) to increase air
temperature, or downwards (BLUE) to reduce air
temperature.
2. Air conditioning switch
Press the switch (indicator lamp illuminates) to
activate the air conditioning. Press again to switch off.
3. Air recirculation control
Move the lever fully upwards to activate air
recirculation. Move the lever fully downwards to
cancel recirculation.
NOTE: Prolonged recirculation may cause
the windows to mist up.
4. Air distribution control
Lever fully up - air to windscreen vents (also provides
some air to the footwell).
Lever midway - air to fascia vents (also provides some
air to the footwell).
Lever fully down - air to footwell vents (also provides
some air to the windscreen).

82AIR CONDITIONING
6
ADJUSTMENT SYSTEM TEST
1.Place the vehicle in a ventilated, shaded area
free from excessive draught, with the doors and
windows open.
2.Check that the surface of the condenser is not
restricted with dirt, leaves, flies, etc. Do not
neglect to check the surface between the
condenser and the radiator. Clean as necessary.
3.Switch on the ignition and the air conditioner air
flow control. Check that the blower is operating
efficiently at low, medium and high speeds.
Switch off the blower and the ignition.
4.Check that the evaporator condensate drain
tubes are open and clear.
5.Check the tension of the compressor driving belt,
and adjust if necessary.
6.Inspect all connections for the presence of
refrigerant oil. If oil is evident, check for leaks,
and repair as necessary.
NOTE: The compressor oil is soluble in
Refrigerant R134a and is deposited when
the refrigerant evaporates from a leak.
7.Start the engine.
8.Set the temperature controls to cold and switch
the air conditioner blower control on and off
several times, checking that the magnetic clutch
on the compressor engages and releases each
time.
9.With the temperature control at maximum
cooling and the blower control at high speed,
warm up the engine and fast idle at 1000
rev/min.
10.Repeat at 1800 rev/min.
11.Gradually increase the engine speed to the high
range and check the sight glass at intervals.
12.Check for frosting on the service valves.
13.Check the high pressure hoses and connections
by hand for varying temperature. Low
temperature indicates a restriction or blockage at
that point.
14.Switch off the air conditioning blower and stop
the engine.
15.If the air conditioning equipment is still not
satisfactory, carry out a pressure test as
previously described in this section.PRECAUTIONS IN HANDLING REFRIGERANT
LINES
WARNING: Wear eye and hand protection
when disconnecting components
containing refrigerant. Plug all exposed
connections immediately.
1.When disconnecting any hose or pipe
connection the system must be discharged of all
pressure. Proceed cautiously, regardless of
gauge readings. Open connections slowly,
keeping hands and face well clear, so that no
injury occurs if there is liquid in the line. If
pressure is noticed, allow it to bleed off slowly.
2.Lines, flexible end connections and components
must be capped immediately they are opened to
prevent the entrance of moisture and dirt.
3.Any dirt or grease on fittings must be wiped off
with a clean alcohol dampened cloth. Do not use
chlorinated solvents such as trichloroethylene. If
dirt, grease or moisture cannot be removed from
inside the hoses, they must be replaced with
new hoses.
4.All replacement components and flexible end
connections must be sealed, and only opened
immediately prior to making the connection.
5.Ensure the components are at room temperature
before uncapping, to prevent condensation of
moisture from the air that enters.
6.Components must not remain uncapped for
longer than 15 minutes. In the event of delay, the
caps must be fitted.
7.Receiver/driers must never be left uncapped as
they contain Silica Gel crystals which will absorb
moisture from the atmosphere. A receiver/ drier
left uncapped must not be used, fit a new unit.
8.The compressor shaft must not be rotated until
the system is entirely assembled and contains a
charge of refrigerant.
9.A new compressor contains an initial charge of
refrigerant oil. The compressor also contains a
holding charge of gas when received which
should be retained by leaving the seals in place
until the pipes are re-connected.
10.The receiver/drier should be the last component
connected to the system to ensure optimum
dehydration and maximum moisture protection of
the system.

AIR CONDITIONING
9
REPAIR EXPANSION VALVE - LH DRIVE
Service repair no - 82.25.01
Remove
1.Remove heater/cooler unit
See Heater/cooler
unit.
2.Suitably support unit on a bench to prevent
damage to heater matrix pipes.
3.Remove 7 screws securing outlet duct to
heater/cooler unit.
4.Break sealing compound around edge of duct
and pull duct from unit.
5.Remove all fixing screws securing top cover
seam and cover sides to main casing.
6.Remove 4 screws and 4 nuts from top of cover.
7.Break sealing compound from unit casing and
top cover.
8.Lift off top cover, release grommet and feed
blower motor wiring and air flap operating rod
through respective apertures. Note thermostat
temperature probe which is inserted in top of
evaporator.
9.Release 2 clips securing expansion valve sensor
and lagging to low pressure pipe.
10.Unscrew union securing expansion valve to
evaporator high pressure pipe.
11.Remove expansion valve, complete with high
pressure pipe.
12.Disconnect high pressure pipe from expansion
valve.
13.Discard all pipe connection 'O' rings.
14.Clean sealing compound from all joints of main
casing, top cover and outlet duct.
Refit
15.Coat unions, threads and new 'O' rings with
refrigerant oil prior to reassembly.
16.Fit high pressure pipe to new expansion valve.
17.Fit expansion valve to evaporator pipe
connector.
18.Position valve sensor at low pressure pipe and
secure with lagging and clips.
19.Apply sealing compound around top edge of
main casing.
20.Feed blower motor wiring through top cover and
fit grommet.
21.Fit top cover to casing. Ensure thermostat
temperature probe is inserted in top of
evaporator. Apply mastic sealant to air flap
operating rod aperture.
22.Apply sealing compound to joint face of blower
motor outlet duct.
23.Locate duct over blower motor outlet and secure
to casing.
24.Fit heater/cooler unit
See Heater/cooler unit.

82AIR CONDITIONING
16
REPAIR EXPANSION VALVE - RH DRIVE
Service repair no - 82.25.01
Remove
1.Remove evaporator
See Evaporator - RH
drive.
2.Unscrew union securing pressure sensor to low
pressure pipe.
3.Release spring clip securing temperature sensor
to low pressure pipe.
4.Unscrew union and remove expansion valve
from evaporator high pressure pipe.
5.Remove high pressure pipe from expansion
valve.
6.Discard all pipe connection 'O' rings.
Refit
7.Coat unions, threads and new 'O' rings with
refrigerant oil prior to reassembly.
8.Fit high presssure pipe to new expansion valve.
9.Fit expansion valve to evaporator high pressure
pipe.
10.Secure temperature and pressure sensors to low
pressure pipe.
11.Fit evaporator
See Evaporator - RH drive.

ELECTRICAL
3
REPAIR ELECTRONIC CONTROL UNIT (ECU)
Service repair no - 86.55.85
Remove
1.Remove LH front seat cushion.
2.Release retaining clip and remove battery
access cover.
3.Slacken battery negative lead clamp bolt.
4.Turn starter switch 'on'.
5.Turn starter switch 'off' and remove key.
6.Disconnect battery negative lead.
NOTE: Operation 6 needs to be carried out
within 15 seconds to avoid activating
battery backed-up alarm sounder, if fitted.
7.Remove steering wheel
See STEERING,
Repair, Steering wheel.
8.Remove 4 screws securing instrument panel to
fascia cowl
See INSTRUMENTS, Repair,
Instrument panel.
9.Pull instrument panel away from fascia cowl and
disconnect speedometer cable, multi-plugs,
alarm LED plug lead, heated rear screen lead,
gearbox oil temperature lead and immobiliser
warning light leads.
10.Remove instrument panel.
11.Remove 2 screws securing ECU to fascia cowl
(LH drive shown). On RH drive vehicles ECU is
positioned lower down, on vertical face of fascia
panel.
12.Release ECU from fascia cowl and disconnect
both multi-plugs.
13.Remove ECU.
NOTE: A new ECU must be initialised
using TestBook.
Refit
14.Position ECU at fascia cowl and reconnect both
multi-plugs.
15.Locate ECU on mounting face of fascia cowl and
secure with 2 screws.
16.Position instrument panel to fascia cowl and
reconnect immobiliser warning light leads,
gearbox oil temperature lead, heated rear screen
lead, alarm LED plug lead, multi-plugs and
speedometer cable.
17.Secure instrument panel to fascia cowl with 4
screws
See INSTRUMENTS, Repair,
Instrument panel.
18.Fit steering wheelSee STEERING, Repair,
Steering wheel.
19.Reconnect battery negative lead.
20.Fit battery access cover.
21.Fit LH seat cushion.

ELECTRICAL
5
REPAIR PASSIVE COIL
Service repair no - 86.77.35
Remove
1.Remove LH front seat cushion.
2.Release retaining clip and remove battery
access cover.
3.Slacken battery negative lead clamp bolt.
4.Turn starter switch 'on'.
5.Turn starter switch 'off' and remove key.
6.Disconnect battery negative lead.
NOTE: Operation 6 needs to be carried out
within 15 seconds to avoid activating
battery backed-up alarm sounder, if fitted.
7.Remove steering wheel
See STEERING,
Repair, Steering wheel.
8.Remove 4 screws securing instrument panel to
fascia cowl
See INSTRUMENTS, Repair,
Instrument panel.
9.Pull instrument panel away from fascia and
disconnect speedometer cable, multi-plugs,
alarm LED plug lead, heated rear screen lead,
gearbox oil temperature lead and immobiliser
warning light leads.
10.Remove instrument panel.
11.Remove 7 screws securing upper and lower
halves of nacelle to steering column mounting
bracket
See STEERING, Repair, Steering
column nacelle.
12.Release multi-switch gaiters from both sides of
nacelle.
13.Remove nacelle upper and lower halves from
steering column; collect blanking grommet from
RH side.
14.Disconnect multi-plug and remove passive coil
from starter switch.
Refit
15.Feed passive coil plug lead into fascia cowl area
and reconnect multi-plug .
16.Fit coil on starter switch.
17.Position nacelle upper and lower halves to
steering column mounting bracket and secure
with 7 screws. Do not fully tighten screws at this
stage
See STEERING, Repair, Steering
column nacelle.
18.Check that passive coil is still fitted correctly on
starter switch.
19.Check fit of nacelle at starter switch and steering
column and fully tighten fixing screws.
20.Fit multi-switch gaiters to both sides of nacelle
and check that blanking grommet is located.
21.Position instrument panel to fascia cowl area
and reconnect immobiliser warning light leads,
gearbox oil temperature lead, heated rear screen
lead, alarm LED plug lead, main harness multi-
plugs and speedometer.
22.Secure instrument panel to fascia cowl with 4
screws
See INSTRUMENTS, Repair,
Instrument panel.
23.Fit steering wheelSee STEERING, Repair,
Steering wheel.
24.Reconnect battery negative lead.
25.Fit battery access cover.
26.Fit LH seat cushion.
27.Test immobilisation and alarm system.

86ELECTRICAL
10
REPAIR Refit
12.Fit alarm indicator light into fascia panel and
reconnect plug lead.
13.Reconnect speedometer cable and fit instrument
panel to fascia cowl.
14.Fit steering wheel
See STEERING, Repair,
Steering wheel.
15.Reconnect battery negative lead.
16.Fit battery access cover.
17.Fit LH seat cushion.ALARM SYSTEM FUSE
Service repair no - 86.77.04
Remove
1.Remove LH front seat cushion.
2.Release retaining clip and remove battery
access cover.
3.Slacken battery negative lead clamp bolt.
4.Turn starter switch 'on'.
5.Turn starter switch 'off' and remove key.
6.Disconnect battery negative lead.
NOTE: Operation 6 needs to be carried out
within 15 seconds to avoid activating
battery backed-up alarm sounder, if fitted.
NOTE: If an alarm sounder without battery
back-up is fitted, it is not necessary to
disconnect battery.
7.Remove steering wheel
See STEERING,
Repair, Steering wheel.
8.Remove 4 screws securing instrument panel to
fascia cowl
See INSTRUMENTS, Repair,
Instrument panel.
9.Pull instrument panel away from fascia and
disconnect speedometer cable, main harness
multi-plugs, alarm LED plug lead, heated rear
screen leads, gearbox oil temperature lead and
immobiliser warning light lead.
10.Remove instrument panel.
11.Remove alarm system 15 amp (blue) fuse from
holder located behind starter switch.