heating LAND ROVER DISCOVERY 1995 Workshop Manual

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04
05
07
09
10
12
17
19
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33
37
41
44
47
51
54
57
60
64
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84
86
Workshop manual
DISCOVERY
This manual covers vehicles from
1995 model year
01 INTRODUCTION
04 GENERAL SPECIFICATION DATA
05 ENGINE TUNING DATA
07 GENERAL FITTING REMINDERS
09 LUBRICANTS, FLUIDS AND CAPACITIES
10 MAINTENANCE
12 ENGINE Tdi
12 ENGINE 3.9 V8
12 ENGINE 4.0 V8
12 ENGINE Mpi
17 EMISSION CONTROL
19 FUEL SYSTEM Tdi
19 FUEL SYSTEM MFI
19 FUEL SYSTEM SFI
19 FUEL SYSTEM Mpi
19 CRUISE CONTROL
26 COOLING SYSTEM Tdi
26 COOLING SYSTEM V8
26 COOLING SYSTEM Mpi
30 MANIFOLD AND EXHAUST SYSTEM
33 CLUTCH
37 MANUAL GEARBOX
41 TRANSFER GEARBOX
44 AUTOMATIC GEARBOX
47 PROPELLER SHAFTS
51 REAR AXLE AND FINAL DRIVE
54 FRONT AXLE AND FINAL DRIVE
57 STEERING
60 FRONT SUSPENSION
64 REAR SUSPENSION
70 BRAKES
74 WHEELS AND TYRES
75 SUPPLEMENTARY RESTRAINT SYSTEM
76 CHASSIS AND BODY
80 HEATING AND VENTILATION
82 AIR CONDITIONING
84 WIPERS AND WASHERS
86 ELECTRICAL
Published by Rover Technical Communication
Ó1996 Rover Group Limited
Publication Part No. LRL 0079 ENG (2nd Edition)

MAINTENANCE
5
MAINTENANCE 2.Clean or replace spark plugs as applicable.
3.It is essential that correct type of spark plugs are
fitted.
4.Incorrect grade of plugs may lead to piston
overheating and engine failure.
Remove
5.Disconnect battery negative lead. Remove H.T.
leads from spark plugs.
6.Remove plugs and washers.
7.When pushing leads onto plugs, ensure that
shrouds are firmly seated.Fitting H.T. leads
8.Ensure replacement H.T. leads are correctly
refitted as illustrated.
Failure to observe this instruction may result in
cross-firing between two closely fitted leads
which are consecutive in firing order.
3.9 V8
4.0 V8

V8i
3
FAULT DIAGNOSIS ENGINE STARTING PROBLEMS
Engine fails to crank in park or neutral (Automatic
Transmission)
1.Is battery in good state of charge?
NO -
See INTRODUCTION, Information,
Jump Starting
YES - Continue.
2.Is automatic transmission inhibitor switch faulty
or gear selection linkage incorrectly adjusted?
YES -
See AUTOMATIC GEARBOX, Repair,
Inhibitor Switch
,
NO -
See Electrical Trouble Shooting
Manual.
If problem is not diagnosed repeat tests, starting
at 1.
Engine fails to crank (Manual Transmission)
1.Is battery in good state of charge?
NO -
See INTRODUCTION, Information,
Jump Starting
YES -See Electrical Trouble Shooting
Manual.
If problem is not diagnosed repeat tests, starting
at 1.
Engine cranks but fails to start
1.Is the cranking speed fast enough (120 rpm)?
NO -
See INTRODUCTION, Information,
Jump Starting
If necessary also.See Electrical Trouble
Shooting Manual.
YES - Continue.
2.Is there combustion in any cylinder?
NO -
See ELECTRICAL, Fault diagnosis,
Lucas Constant Energy Ignition
System - V8i See Electrical Trouble
Shooting Manual.
YES - Continue.
3.Are the fuel supply, tank, pump, ventilation and
emission control systems in correct working
order or the fuel contaminated?
NO -
See FUEL SYSTEM, Repair, Fuel
Filter See FUEL SYSTEM, Repair,
Fuel Tank See FUEL SYSTEM, Repair,
Fuel pump and Sender Unit See
EMISSION CONTROL, Description and
operation, Emission control
If problem is not diagnosed repeat tests, starting
at 2.ENGINE RUNNING PROBLEMS
Engine runs at high speed but will not idle (stops)
Engine idle speed erratic Engine starts but stops
immediately
Engine stalls Engine misfires/hesitation
1.Multiport fuel injection.
See Electrical Trouble
Shooting Manual. See ELECTRICAL, Fault
diagnosis, Lucas Constant Energy Ignition
System - V8i
Check brake vacuum connections.See
BRAKES, Description and operation, Brake
Servo Unit
Check heater/ventilation unit vacuum
connections.
See HEATING AND
VENTILATION, Description and operation,
Heating and Ventilation Unit
If problem is not diagnosed continue.
2.Are HT leads correctly routed and clipped?
NO -
See ELECTRICAL, Repair, Distributor
- V8i
YES - Continue.
3.Is fuel supply, tank, pump, ventilation and
emission control systems in correct working
order or the fuel contaminated?
NO -
See FUEL SYSTEM, Repair, Fuel
Filter See FUEL SYSTEM, Repair,
Fuel Tank See FUEL SYSTEM, Repair,
Fuel Pump and Sender Unit See
EMISSION CONTROL, Description and
operation, Emission Control
If problem is not diagnosed repeat tests, starting
at 1.
Engine lacks power/poor performance
1.Is throttle travel restricted or cable incorrectly
adjusted?
YES - Check thickness of carpets.
See FUEL
SYSTEM, Repair, Throttle Cable See
FUEL SYSTEM, Repair, Accelerator
Pedal
NO - Continue.
2.Are the Ignition and Multiport Fuel Injection
systems in order?
NO -
See Electrical Trouble Shooting
Manual.A1 See ELECTRICAL, Fault
diagnosis, Lucas Constant Energy
Ignition System - V8i See
ELECTRICAL, Repair, Distributor - V8i
YES - Continue.

12ENGINE
4
FAULT DIAGNOSIS 3.Are fuel supply, tank, pump, ventilation and
emission control systems in correct working
order or the fuel contaminated?
NO -
See FUEL SYSTEM, Repair, Fuel
Filter See FUEL SYSTEM, Repair,
Fuel Tank See FUEL SYSTEM, Repair,
Fuel Pump and Sender Unit
YES - Suspect valves held open by hydraulic
tappets due to high oil pressure.
See
Engine Oil Pressure Test
4.Is oil pressure high?
YES - Remove oil filter and cooler adaptor and
check pressure relief valve strainer gauze
for blockage and that the relief valve is
not stuck closed.
See Description and
operation, Description
NO - Carry out cylinder compression tests to
determine condition of head gaskets and
valves.
See Cylinder Compression -
Test
5.Are cylinder compressions satisfactory?
NO -
See Repair, Cylinder Heads - Renew
YES - Check brake vacuum connections.See
BRAKES, Description and operation,
Brake Servo Unit
Check heater/ventilation unit vacuum connections.
See HEATING AND VENTILATION, Description and
operation, Heating and Ventilation Unit
If problem is not diagnosed: Continue.
6.Are the brakes binding?
YES - Investigate cause of binding.
NO - Continue.
7.Automatic Transmission only. Is the Torque
Converter and Transmission operating correctly?
Carry out Road test, Static tests and Stall tests
to determine condition of Automatic
transmission.
If problem is not diagnosed: repeat tests starting at 1.Engine backfires into exhaust system
1.Are there any leaking joints/connections or holes
in the exhaust system?
YES -
See MANIFOLD AND EXHAUST
SYSTEM, Repair, Exhaust System
Complete
NO - Continue.
2.Is distributor fitted correctly, HT leads in correct
firing order and routed correctly?
NO -
See ELECTRICAL, Repair, Distributor
- V8i
YES - Continue.
3.Is air fuel ratio correct?
NO - Check multiport fuel injection.
See
Electrical Trouble Shooting Manual.
Check brake vacuum connections.See
BRAKES, Description and operation, Brake
Servo Unit
Check heater/ventilation unit vacuum
connections.
See HEATING AND
VENTILATION, Description and operation,
Heating and Ventilation Unit
Check the crank case and fuel tank ventilation
system.
See EMISSION CONTROL,
Description and operation, Emission Control
YES - Continue.
4.Are cylinder compressions satisfactory?
NO - Carry out compression test to check for
leaking gaskets valves etc.
See
Cylinder Compression - Test
See Repair, Cylinder Heads - Renew
If problem is not diagnosed: repeat tests starting
at 1.

V8i
5
FAULT DIAGNOSIS Engine backfires into inlet system
1.Is the Distributor, HT connections and routing
correct?
NO -
See ELECTRICAL, Repair, Distributor
- V8i
YES - Continue.
2.Is air fuel ratio correct?
NO - Check multiport fuel injection.
See
Electrical Trouble Shooting Manual.
Check brake vacuum connections.See
BRAKES, Description and operation, Brake
Servo Unit
Check heater/ventilation unit vacuum
connections.
See HEATING AND
VENTILATION, Description and operation,
Heating and Ventilation Unit
Check the crank case and fuel tank ventilation
system.
See EMISSION CONTROL,
Description and operation, Emission Control
YES - Continue.
3.Are cylinder compressions satisfactory?
NO - Carry out compression test to check for
leaking gaskets valves etc.
See
Cylinder Compression - Test
For repairSee Repair, Cylinder Heads -
Renew
If problem is not diagnosed: repeat tests starting
at 1.

19FUEL SYSTEM
6
DESCRIPTION AND OPERATION DESCRIPTION ELECTRONIC DIESEL CONTROL
The Electronic Diesel Control (EDC) 'drive by wire'
system derives its from the replacement of
conventional mechanical controls by electronic
components.
The EDC system supplies the exact amount of fuel to
the engine according to the prevailing engine
operating conditions. To monitor these conditions,
sensors are fitted to the engine to measure engine
parameters. Data from the sensors is received by the
Engine Control Module (ECM) which determines the
exact amount of fuel, injection timing and Exhaust
Gas Recirculation (EGR) required for any running
condition.
Safety and emergency features are built into the
system which protect the engine against overspeed
and overheating damage. In the event of component
failure the system is designed to compensate and
allow emergency start and limp home facilities to
operate. The ECM does this by substituting a default
value for the failed component which may result in a
noticeable loss in power but keeps the engine
running.FUEL SYSTEM COMPONENT LOCATION EDC
1. Vehicle speed sensor
2. No. 4 injector sensor
3. Coolant temperature sensor
4. Boost pressure sensor
5. Electro-pneumatic modulator
6. Airflow sensor
7. Engine speed sensor
8. Brake/clutch switches
9. Injector pump
10. Throttle position sensor
11. Engine control module

19FUEL SYSTEM
2
DESCRIPTION AND OPERATION Fuel pressure regulator
The fuel pressure regulator is mounted in the fuel rail
at the rear of the plenum chamber. The regulator is a
mechanical device controlled by plenum chamber
vacuum, it ensures that fuel rail pressure is
maintained at a constant pressure difference of 2.5
bar above that of the manifold.
When pressure exceeds the regulator setting excess
fuel is returned to the fuel tank.
Fuel pump
The electric fuel pump is located in the fuel tank, and
is a self priming 'wet' pump, the motor is immersed in
the fuel within the tank.
Air flow sensor
The hot-wire air flow sensor is mounted on a bracket
attached to the left hand valance, rigidly connected to
the air cleaner and by hose to the plenum chamber
inlet neck.
The air flow sensor consists of a cast alloy body
through which air flows. A proportion of this air flows
through a bypass in which two wire elements are
situated: one is a sensing wire and the other is a
compensating wire. Under the control of an electronic
module which is mounted on the air flow sensor body,
a small current is passed through the sensing wire to
produce a heating effect. The compensating wire is
also connected to the module but is not heated, but
reacts to the temperature of the air taken in, as engine
intake air passes over the wires a cooling effect takes
place.
The electronic module monitors the reaction of the
wires in proportion to the air stream and provides
output signals in proportion to the air mass flow rate
which are compatible with the requirements of the
ECM.Throttle position sensor
The throttle position sensor is mounted on the side of
the plenum chamber inlet neck and is directly coupled
to the throttle butterfly shaft.
The throttle position sensor is a resistive device
supplied with a voltage from the ECM. Movement of
the accelerator pedal causes the throttle valve to
open, thus rotating the wiper arm within the throttle
position sensor which in turn varies the resistance in
proportion to the valve position. The ECM lengthens
the injector open time when it detects a change in
output voltage (rising) from the throttle position
sensor.
In addition the ECM will weaken the mixture when it
detects the throttle position sensor output voltage is
decreasing under deceleration and will shorten the
length of time the injectors are open.
When the throttle is fully open, the ECM will detect the
corresponding throttle position sensor voltage and will
apply full load enrichment. This is a fixed percentage
and is independent of temperature. Full load
enrichment is also achieved by adjusting the length of
the injector open time.
When the throttle is closed, overrun fuel cut off or idle
speed control may be facilitated dependant on other
inputs to the ECM.
The throttle position sensor is 'self adaptive', which
means that adjustment is not possible. It also means
the throttle position sensor setting is not lost, for
example, when throttle stop wear occurs.
CAUTION: Do not attempt to adjust throttle
position sensor.

Mpi
5
DESCRIPTION AND OPERATION
Fuel pump
The electric fuel pump, located inside the fuel tank, is
a self-priming centrifugal 'wet' pump, the motor and
pump are filled with fuel.
The fuel pump supplies more fuel than the maximum
load requirement for the engine, so that pressure in
the fuel system can be maintained under all
conditions.
Fuel pressure regulator
The pressure regulator is a mechanical device
controlled by manifold depression and is mounted in
the fuel rail. The regulator ensures that fuel rail
pressure is maintained at a constant pressure
difference to that in the inlet manifold, as manifold
depression increases the regulated fuel pressure is
reduced in direct proportion.
When pressure exceeds the regulator setting excess
fuel is spill returned to the fuel tank swirl pot which
contains the fuel pick-up strainer.
Relay module
The relay module contains the main relay, fuel pump
relay, starter relay and oxygen sensor relay and is
mounted on the ECM mounting bracket.
The main relay is energised when the ignition is
switched on and supplies current to the ECM
The fuel pump relay is energised by the ECM for a
short period when the ignition is switched on, during
cranking and while the engine is running.
The starter relay is energised by the cranking signal
from the ignition switch.
This oxygen sensor relay is energised when the
ignition is switched on and supplies current to the
ECM
Intake air temperature sensor
The intake air temperature sensor is fitted in the side
of the inlet manifold and sends the ECM a signal
relating to air temperature. The ECM uses this signal
in its calculations on air flow.
Inertia switch
The fuel pump circuit incorporates an inertia switch
which in the event of sudden deceleration isolates the
power supply to the fuel pump. The inertia switch is
situated in the engine compartment on the bulkhead
and can, if tripped, be reset by depressing the central
plunger.
WARNING: Check the integrity of the fuel
system before the inertia switch is reset.
Diagnostic connector
A diagnostic connector is provided to enable
diagnosis to be carried out without disturbing the
system electrical connections and to allow the ECM's
ability to store certain faults to be utilised.
Oxygen sensor - Closed-loop emission control
The MEMS Mpi system operates a closed loop
emission system to ensure the most efficient level of
exhaust gas conversion.
An oxygen sensor fitted in the exhaust manifold
monitors the exhaust gases. It then supplies a small
voltage proportional to exhaust oxygen content to the
ECM As the air/fuel mixture weakens, the exhaust
oxygen content increases and so the voltage to the
ECM decreases. If the mixture becomes richer so the
oxygen content decreases and the voltage increases.
The ECM uses this signal voltage to determine the
air/fuel mixture being delivered to the engine, and
adjusts the injector duration to maintain the ratio
necessary for efficient gas conversion by the catalyst.
The oxygen sensor has an integral heating element to
ensure an efficient operating temperature is quickly
reached from cold. The electrical supply for the heater
element is controlled by the oxygen sensor relay.
Fuel temperature sensor
The fuel temperature sensor is inserted in the fuel rail
and measures fuel and fuel rail temperatures. During
engine cranking at high temperatures, the ECM
increases fuel supply, and opens the throttle disc via
the stepper motor to aid hot starting.

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.

V8i
1
DESCRIPTION AND OPERATION ENGINE COOLING
Description
The V8i engine uses a pressurised cooling system
and cross flow radiator which is supplied from a
separate header tank. The coolant radiator also
incorporates a section at the left hand end for cooling
the transmission oil and a section at the other end for
cooling the engine oil.The belt driven viscous fan and centrifugal water
pump is located in the engine front cover with ports for
circulation of coolant to both banks of cylinders and
cylinder heads. Coolant returns to the top of the
radiator via ports in the inlet manifold where the
thermostat is mounted horizontally.
Coolant also circulates through the vehicle heating
system and is used to heat air entering the inlet
manifold plenum chamber.
Coolant circulation (engine hot)
1. Cross flow radiator
2. Header tank
3. Viscous fan and water pump
4. Heater pipes
5. Plenum chamber connection
6. Thermostat