cooling LAND ROVER DEFENDER 1996 User Guide

ENGINE
7
REPAIR Refit
12.Lightly grease pulley spigot and locate pulley
onto cranshaft.
13.Fit pulley retaining bolt.
14.Fit pulley retainerLRT-12-080and secure with 4
bolts.
15.Tighten pulley nut to
80 Nm (59 lbf/ft)+90°.
16.Remove pulley retainer.
17.Fit drive belt.
See ELECTRICAL, Repair,
Auxiliary drive belt; Refit
18.Fit fan cowl.See COOLING SYSTEM, Repair,
Fan cowl
19.Fit viscous coupling and fan.See COOLING
SYSTEM, Repair, Viscous coupling and fan
20.Fit intercooler to induction manifold hose.
21.Fit radiator top hose.
22.Refill cooling system.
See COOLING SYSTEM,
Repair, Drain and refill cooling system
23.Reconnect battery.FRONT COVER PLATE AND SEAL
Service repair no - 12.65.01
Remove
1.Disconnect battery.
2.Drain coolant.
See COOLING SYSTEM,
Repair, Drain and refill cooling system
3.Remove top hose from radiator.
4.Remove intercooler to induction manifold hose.
5.Remove viscous coupling and fan.
See
COOLING SYSTEM, Repair, Viscous
coupling and fan
6.Remove fan cowl.See COOLING SYSTEM,
Repair, Fan cowl
7.Remove drive belt.See ELECTRICAL, Repair,
Auxiliary drive belt
8.Remove crankshaft pulley.See Crankshaft
pulley
9.Remove 14 bolts securing front cover plate. Note
that top 2 bolts also retain thermostat hose clips.
10.Remove cover plate complete with gasket.
11.Remove small gasket from centre bolt boss.
Seal replacement
12.Remove worn seal from cover and clean recess.
13.Support cover and fit new seal, open side fitted
into recess, using special toolLRT-12-077.

12ENGINE
8
REPAIR Refit
14.Fit gasket to centre bolt boss.
15.Locate new gasket and fit front cover plate using
fixing bolts as shown. Tighten bolts to
25 Nm (18
lbf/ft).
1- 25 mm,2- 35 mm,3- 50 mm,4- 100 mm,5- 110
mm
16.Fit crankshaft pulley.
See Crankshaft pulley
17.Fit drive belt.See ELECTRICAL, Repair,
Auxiliary drive belt
18.Fit fan cowl.See COOLING SYSTEM, Repair,
Fan cowl
19.Fit viscous coupling and fan.See COOLING
SYSTEM, Repair, Viscous coupling and fan
20.Fit intercooler to induction manifold hose.
21.Fit top hose to radiator.
22.Refill cooling system.
See COOLING SYSTEM,
Repair, Drain and refill cooling system
23.Reconnect battery.CAMSHAFT DRIVE BELT
Service repair no - 12.65.18
Remove
1.Remove front cover plate.
See Front cover
plate
2.Position engine at TDC on No. 1 cylinder.
3.Remove blanking plug from flywheel housing
and insert timing toolLRT-12-044.
4.Engage timing tool pin with slot in flywheel.
5.Check correct alignment of timing mark on
camshaft gear and that crankshaft key aligns
with cast arrow on housing.
6.Insert pin from special toolLRT-12-045in
injection pump gear and through into pump
flange.

ENGINE
15
REPAIR FLYWHEEL
Service repair no - 12.53.07
Remove
1.Disconnect battery.
2.Remove gearbox.
See MANUAL GEARBOX,
Repair, R380 gearbox
3.Remove clutch.See CLUTCH, Repair, Clutch
assembly
4.Fit 2, long, 8 mm bolts into the clutch bolt holes,
as shown, to use as handles when lifting the
flywheel off the crankshaft.
5.Remove fan cowl.
See COOLING SYSTEM,
Repair, Fan cowl
6.Fit crankshaft pulley retainerLRT-12-080and
secure with 4 bolts, to restrain crankshaft while
removing flywheel retaining bolts.
7.Remove bolts and lift off flywheel.
Refit
NOTE: To prevent excessive flywheel
run-out, ensure that mating faces of
flywheel and crankshaft are clean.
8.Locate flywheel on crankshaft, remove lifting
bolts, and secure flywheel with new patched
retaining bolts, progressively tighten to
147 Nm
(108 lbf/ft).
9.Check the flywheel for possible run-out by
mounting a dial test indicator with the stylus in a
loaded condition resting on the flywheel face at a
radius of 114 mm (4.50 in) from the centre.
10.Turn flywheel and check that run-out does not
exceed 0,07 mm (0.003 in).
11.Should run-out be excessive, remove flywheel
and check again for irregularities on crankshaft
and flywheel mating faces and location dowel.
12.Remove crankshaft pulley retainer.
13.Fit fan cowl.
See COOLING SYSTEM, Repair,
Fan cowl
14.Fit clutch.See CLUTCH, Repair, Clutch
assembly
15.Fit gearbox.See MANUAL GEARBOX, Repair,
R380 gearbox
16.Reconnect battery.

12ENGINE
20
REPAIR OIL FILTER HEAD GASKET
Service repair no - 12.60.03
Remove
1.Clean filter head adaptor.
2.Disconnect oil cooler pipes and plug to prevent
ingress of dirt.
3.Disconnect oil pressure switch lead.
4.Remove 4 bolts and withdraw filter head,
complete with gasket.
5.Clean mating faces of filter head and cylinder
block.
6.Fit head with new gasket.
7.Tighten bolts to
45 Nm (33 lbf/ft).
8.Reconnect oil pressure switch lead.
9.Reconnect oil cooler pipes.CYLINDER HEAD GASKET
Service repair no - 12.29.02
Remove
1.Disconnect battery
2.Remove bonnet.
3.Drain coolant.
See COOLING SYSTEM,
Repair, Drain and refill cooling system
4.Remove air cleaner.See FUEL SYSTEM,
Repair, Air cleaner
5.Detach crankcase ventilation valve and side
breather hose from rocker cover and move to
one side.
6.Remove fuel injectors and pipes.
See FUEL
SYSTEM, Repair, Fuel injectors
7.Remove heater plugs.See FUEL SYSTEM,
Repair, Heater plugs
8.Disconnect radiator top hose from thermostat.
9.Disconnect bleed hose at thermostat.
10.Disconnect water pump hose at thermostat.
11.Disconnect water temperature sensor lead.

ENGINE
23
REPAIR
43.Check and adjust valve clearances.
See Adjustment, Valve clearances - check
and adjust
44.Fit rocker cover, ensuring oil seal is satisfactory
for continued use, and renew if necessary.
45.Secure rocker cover with special seal washers
and nuts. Tighten to
10 Nm (7 lbf/ft).
46.Fit rear engine lifting bracket, securing breather
pipe and multi-plug retaining clips. Tighten fixing
bolts to
25 Nm (18 lbf/ft).
47.Fit engine harness bracket to cylinder head.
48.Secure air cleaner mounting bracket to support
strut.
49.Connect heater hose to rear of cylinder head.
50.Position heater rail and connect hose from water
pump.
51.Fit exhaust manifold and turbocharger assembly.
See MANIFOLD AND EXHAUST SYSTEM,
Repair, Exhaust manifold
52.Fit induction manifold.See MANIFOLD AND
EXHAUST SYSTEM, Repair, Induction
manifold
53.Connect water temperature sensor lead.
54.Connect water pump hose at thermostat.
55.Fit bleed hose at thermostat.
56.Connect radiator top hose at thermostat.
57.Fit heater plugs.
See FUEL SYSTEM, Repair,
Heater plugs
58.Fit fuel injectors.See FUEL SYSTEM, Repair,
Fuel injectors
59.Fit crankcase ventilation valve and side breather
hose.
60.Fit air cleaner.
See FUEL SYSTEM, Repair,
Air cleaner
61.Refill cooling system.See COOLING SYSTEM,
Repair, Drain and refill cooling system
62.Fit bonnet.
63.Reconnect battery.OIL PUMP
Service repair no - 12.60.26
Remove
1.Remove engine front cover.
See Front cover
gasket
2.Remove 7 screws and release oil pump retaining
plate from engine front cover.
3.Mark oil pump inner gear rotor, outer gear rotor
and front cover housing for reassembly.
4.Check for rotor clearances:
Outer rotor to housing, 0,025 - 0,075 mm (0.010
- 0.030 in).
Inner rotor to outer rotor, 0,025 - 0,075 mm
(0.010 - 0.030 in).
Rotor end float, 0,026 - 0,135 mm (0.010 - 0.054
in).
5.Remove inner and outer rotors.
6.Check condition of oil pump components.
NOTE: If the oil pump seating in the front
cover or retaining plate is badly worn,
pitted or scored, a new front cover must
be fitted.
See Front cover gasket
Always renew oil pump rotors as a pair.
7.Clean sealant from pump retaining plate and
front cover.

FUEL SYSTEM
9
DESCRIPTION AND OPERATION OPERATION
Diesel engines operate by compression ignition. The
rapid compression of air in the cylinder during the
compression cycle heats the air and when fuel is
injected into the heated air, it ignites instantaneously.
During cold tarting, automatically controlled heater
plugs assist in raising the temperature of the
compressed air to ignition point.
A cold start advance unit advances the injection timing
to further assist starting. Idle quality is improved by
the high idle setting.
The engine is supplied with pre-compressed air by a
single stage turbocharger.
Exhaust gases passing over a turbine cause it to
rotate, driving a compressor mounted on the turbine
shaft. Air drawn from the cold air intake passes, via
the air cleaner, to the turbocharger where it is
compressed. Compression in the turbocharger warms
up the air considerably, so that it expands. As a result
the air mass per cylinder is reduced, having a
negative effect on power output. By fitting a charge-air
intercooler, located on the LH side of the radiator, the
air is cooled before reaching the cylinders. This
increases power output through increased mass of
oxygen in the combustion process, as well as
maximising engine durability, through maintaining
lower piston and head temperatures.
Fuel is drawn from the tank by a mechanical lift pump
and passes to the injection pump via a filter. In
addition to removing particle contamination from the
fuel, the filter incorporates a water separator, which
removes and stores water.
The sedimentor/s, when fitted, is located adjacent to
the fuel tank/s and separates contamination and water
particles in the fuel before reaching the fuel lift pump.
The injection pump meters a precisely timed, exact
quantity of fuel to the injectors in response to throttle
variations, injection timing varying with engine speed.
Any excess fuel delivered to the injection pump is
passed back to the tank via the spill return line.
Fuel is injected in a finely atomised form into the main
combustion chamber, the burning fuel expands
rapidly, creating extreme turbulence which mixes the
burning fuel thoroughly with the compressed air,
providing complete combustion.Cold Starting is assisted by heater plugs, a cold start
advance unit and a high idle setting.
Heater plugs
Heater plug operation is controlled by a timer unit,
start relay and resistor. When the ignition is turned on
the timer unit is energised, the heater plugs start to
operate and a warning light on the dashboard
illuminates, remaining on until the heater plugs are
automatically switched off.
The length of time the heater plugs will operate is
dependent on under bonnet temperature, which is
monitored by a sensor located in the timer unit.
Starting the engine results in the power supply to the
heater plugs passing through the resistor, which
reduces their operating temperature. The heater plugs
are cut out either by the temperature sensor in the
timer, or by a microswitch on the injection pump which
operates when the throttle is depressed.
Cold start advance
The cold start advance unit is connected to the engine
cooling system via hoses. It contains a temperature
sensitive element which is retracted when cold and
pulls the advance lever, via cable, towards the rear of
the pump against spring pressure. As coolant
temperature rises, the cold start element expands
releasing tension on the cable and allowing spring
pressure to move the advance lever forwards.
Exhaust gas recirculation (EGR), when fitted
Operation of the EGR system is dependent on the
following:
·Engine temperature - must be between 20°C and
100°C approx.
·Engine speed - must be between 630 and 2850
rev/min.
·Engine load - calculated by throttle position
sensor.
·EGR valve lift position.
·Duration of engine idling.

COOLING SYSTEM
1
DESCRIPTION AND OPERATION ENGINE COOLING SYSTEM
Description
The complete cooling system of the 300Tdi engine
incorporates three independent functions:- Engine
(coolant) cooling; Turbo (charge air) intercooling;
Engine oil cooling.The intercooler is a separate aluminium unit, located
on the LH side of the engine compartment adjacent to
the radiator, sharing the same upper and lower
mountings. For details of turbo intercooling
See
FUEL SYSTEM, Description and operation,
Operation
. The oil cooler matrix is an integral part of
the radiator. Pre-formed pipes/hoses are used to link
the components within the separate systems as
shown below.
Engine cooling system
1.Radiator
2.Thermostat housing
3.Radiator bottom hose
4.Viscous fan
5.Water pump
6.Radiator top hose
7.Heater return hose
8.Coolant supply hose
9.By-pass hose
10.Radiator bleed (purge) hose
11.Bleed (purge) hose, thermostat housing
12.'Y' piece ejector
13.Expansion tank14.Heater rail
15.Heater unit
16.Heater feed hose
17.Intercooler
18.Air cleaner
19.Air feed hose
20.Turbocharger
21.Charge air supply pipe/hose
22.Cooled charge air supply hose
23.Exhaust manifold
24.Engine oil cooler
25.Feed pipe, engine oil cooler
26.Return pipe, engine oil cooler
27.Oil filter

26COOLING SYSTEM
2
DESCRIPTION AND OPERATION ENGINE (COOLANT) COOLING
Description
The 300Tdi engine uses a pressurised cooling system
and cross flow radiator which is supplied with coolant
from an expansion tank mounted on the RH side of
the engine compartment. A belt driven centrifugal
water pump, fitted to an auxiliary mounting assembly,pumps coolant to the engine crankcase, cylinder head
and vehicle heater unit.
An eleven bladed fan, incorporating a viscous
coupling, is driven by an independent pulley secured
to the front cover plate. The thermostat housing,
bolted to the front of the cylinder head, is fitted with a
vent valve that purges excessive air pressure and
coolant back to the expansion tank.
Engine coolant circulation (engine warm - thermostat open).
1.Radiator
2.Thermostat/housing
3.Radiator bottom hose
4.Viscous fan
5.Water pump
6.Radiator top hose
7.Heater return hose
8.Coolant supply hose9.By-pass hose
10.Radiator bleed (purge) hose
11.Thermostat housing bleed (purge) hose
12.'Y' piece ejector
13.Expansion tank
14.Heater rail
15.Heater unit
16.Heater feed hose

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.

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.