lock LAND ROVER DEFENDER 1999 Workshop Manual

COOLING SYSTEM
7
DESCRIPTION AND OPERATION Radiator
The 44 row radiator is located at the front of the vehicle in the engine compartment. The cross flow type radiator is
manufactured from aluminium with moulded plastic end tanks interconnected with tubes. The bottom four rows are
separate from the upper radiator and form the lower radiator for the fuel cooler. Aluminium fins are located
between the tubes and conduct heat from the hot coolant flowing through the tubes, reducing the coolant
temperature as it flows through the radiator. Air intake from the front of the vehicle when moving carries the heat
away from the fins. When the vehicle is stationary, the viscous fan draws air through the radiator fins to prevent
the engine from overheating.
Two connections at the top of the radiator provide for the attachment of the top hose from the outlet housing and
bleed pipe to the expansion tank. Three connections at the bottom of the radiator allow for the attachment of the
bottom hose to the thermostat housing and the return hose from the oil cooler and the feed hose to the fuel cooler.
The bottom four rows of the lower radiator are dedicated to the fuel cooler. The upper of the two connections at
the bottom of the radiator receives coolant from the oil cooler. This is fed through the four rows of the lower
radiator in a dual pass and emerges at the lower connection. The dual pass lowers the coolant temperature by up
to 24°C before being passed to the fuel cooler. Two smaller radiators are located in front of the cooling radiator.
The upper radiator is the intercooler for the air intake system and the lower radiator provides cooling of the
gearbox oil.
Pipes and Hoses
The coolant circuit comprises flexible hoses and metal formed pipes which direct the coolant into and out of the
engine, radiator and heater matrix. Plastic pipes are used for the bleed and overflow pipes to the expansion tank.
A bleed screw is installed in the radiator top hose and is used to bleed air during system filling. A drain plug to
drain the heater and cylinder block circuit of coolant is located on the underside of the coolant pump feed pipe.
Oil Cooler
The oil cooler is located on the left hand side of the engine block behind the oil centrifuge and oil filter. Oil from the
oil pump is passed through a heat exchanger which is surrounded by coolant in a housing on the side of the
engine.
Full water pump flow is directed along the cooler housing which also distributes the flow evenly along the block
into three core holes for cylinder cooling. This cools the engine oil before it is passed into the engine. A small
percentage of the coolant from the oil cooler passes into a metal pipe behind the engine. It then flows into the
lower radiator via a hose.
Fuel Cooler
The fuel cooler is located on the right hand side of the engine and is attached to the inlet manifold. The cooler is
cylindrical in design and has a coolant feed connection at its forward end. A’T’connection at the rear of the cooler
provides a connection for the coolant return from the heater matrix and coolant return from the fuel cooler.
The’T’connection houses a thermostat which opens at approximately 82°C. This prevents the cooler operating in
cold climates. Two quick release couplings on the cooler allow for the connection of the fuel feed from the
pressure regulator and return to the fuel tank. A counter flow system is used within the cooler.
Fuel flows around a coolant jacket within the cooler and flows from the back to the front of the cooler. As the hot
fuel cools travelling slowly forwards it meets progressively colder coolant travelling in the opposite direction
maintaining a differential cooling effect.
ProCarManuals.com

26COOLING SYSTEM
8
DESCRIPTION AND OPERATION Coolant Pump
1.Drive lugs (hidden)
2.Housing
3.’O’rings4.Cover
5.Feed hose connection
6.Impeller
The coolant pump is attached on the left hand side of the engine, behind the PAS pump. A cast housing, bolted to
the cylinder block provides a common attachment point for both pumps. The housing has galleries which connect
the coolant pump to the cylinder block and the oil cooler housing. The coolant pump comprises a shaft, a housing
and a cover.
The shaft, which passes through the alloy housing, is supported at each end by bearings. Seals at each end of the
shaft protect the bearings from the coolant. The forward end of the shaft has two lugs which engage with the PAS
pump shaft. The opposite end of the shaft is fitted with an impeller which draws coolant from the feed pipe and
circulates it through galleries in the cylinder block. The shaft is driven by the auxiliary drive belt at the same
rotational speed as the crankshaft by a pulley attached to the PAS pump.
The pump is sealed in the cast housing with two’O’rings. An outer cover is positioned over the pump and secured
with six bolts and sealed to the pump with an’O’ring. The cover provides the attachment for the feed pipe
connecting hose.
ProCarManuals.com

COOLING SYSTEM
9
DESCRIPTION AND OPERATION Viscous Fan
1.Idler pulley drive attachment
2.Fan blades3.Bi-metallic coil
4.Body
The viscous fan provides a means of controlling the speed of the fan relative to the operating temperature of the
engine. The fan rotation draws air through the radiator, reducing engine coolant temperatures when the vehicle is
stationary or moving slowly.
The viscous fan is attached to an idler pulley at the front of the engine which is driven at crankshaft speed by the
auxiliary drive belt. The fan is secured to the pulley by a right hand threaded nut. The nut is positively attached to
the fan spindle which is supported on bearings in the fan body. The viscous drive comprises a circular drive plate
attached to the spindle and driven from the idler pulley. The drive plate and body have interlocking annular
grooves with a small clearance which provides the drive when silicone fluid enters the fluid chamber. A bi-metallic
coil is fitted externally on the forward face of the body. The coil is connected to and operates a valve in the body.
The valve operates on a valve plate with ports that connect the reservoir to the fluid chamber. The valve plate also
has return ports which, when the valve is closed, scoop fluid from the fluid chamber and push it into the reservoir
under centrifugal force.
Silicone fluid is retained in a reservoir at the front of the body. When the engine is off and the fan is stationary, the
silicone fluid level stabilises between the reservoir and the fluid chamber. This will result in the fan operating when
the engine is started, but the drive will be removed quickly after the fan starts rotating and the fan will’freewheel’.
ProCarManuals.com

COOLING SYSTEM
11
DESCRIPTION AND OPERATION OPERATION
Coolant Flow - Engine Warm Up
During warm up the coolant pump moves fluid through the cylinder block and it emerges from the outlet housing.
From the outlet housing, the warm coolant flow is prevented from flowing through the upper and lower radiators
because both thermostats are closed. The coolant is directed into the heater circuit.
Some coolant from the by-pass pipe can pass through small sensing holes in the flow valve. The warm coolant
enters a tube in the thermostat housing and surrounds 90% of the thermostat sensitive area. Cold coolant
returning from the radiator bottom hose conducts through 10% of the thermostat sensitive area. In cold ambient
temperatures the engine temperature can be raised by up to 10°C (50°F) to compensate for the heat loss of the
10% exposure to the cold coolant return from the radiator bottom hose.
At engine speeds below 1500 rev/min, the by-pass valve is closed only allowing the small flow through the sensing
holes. As the engine speed increases above 1500 rev/min, the greater flow and pressure from pump overcomes
the light spring and opens the by-pass flow valve. The flow valve opens to meet the engine’s cooling needs at
higher engine speeds and prevents excess pressure in the cooling system. With both thermostats closed,
maximum flow is directed through the heater circuit.
The heater matrix acts as a heat exchanger reducing the coolant temperature as it passes through the matrix.
Coolant emerges from the heater matrix and flows to the fuel cooler’T’connection via the heater return hose.
From the fuel cooler the coolant is directed into the coolant pump feed pipe and recirculated around the heater
circuit. In this condition the cooling system is operating at maximum heater performance.
Coolant Flow - Engine Hot
As the coolant temperature increases the main thermostat opens. This allows some coolant from the outlet
housing to flow through the top hose and into the radiator to be cooled. The hot coolant flows from the left tank in
the radiator, along the tubes to the right tank. The air flowing through the fins between the tubes cools the coolant
as it passes through the radiator.
A controlled flow of the lower temperature coolant is drawn by the pump and blended with hot coolant from the
by-pass and the heater return pipes in the pump feed pipe. The pump then passes this coolant, via the cylinder
block, to the oil cooler housing, cooling the engine oil before entering the block to cool the cylinders.
When the fuel temperature increases, the heat from the fuel conducts through the fuel cooler’T’connection and
causes the fuel thermostat to open. Coolant from the cylinder block flows through the oil cooler and via a pipe and
hose enters the lower radiator. The lower temperature coolant from the oil cooler housing is subjected to an
additional two passes through the lower radiator to further reduce the coolant temperature. From the lower radiator
the coolant flows , via a hose, to the fuel cooler.
As the hot fuel cools, travelling slowly forwards through the cooler, it meets the progressively colder coolant
travelling in the opposite direction from the lower radiator.
ProCarManuals.com

MANIFOLD AND EXHAUST SYSTEM
3
DESCRIPTION AND OPERATION Front pipe assembly
The front pipe is of welded and fabricated tubular construction. The front pipe is connected to a flange on the
turbocharger and secured with three flanged nuts and sealed with a metal laminated gasket. The front pipe
incorporates a flexible pipe near the connection with the turbocharger and terminates in a flanged connection with
the intermediate pipe.
The flexible pipe is formed into a concertina shape with woven metal strands around its outer diameter. The
flexible pipe allows for ease of exhaust system alignment and also absorbs engine vibration. The woven metal
strands also increase the longevity of the flexible pipe.
The front pipe is attached via a bracket and a mounting rubber to the chassis. The mounting rubber allows ease of
alignment and vibration absorption.
Intermediate pipe and silencer
The intermediate pipe is of welded and fabricated tubular construction. It connects at its forward end to the front
pipe flange. Two captive studs on the intermediate pipe flange allow for attachment to the front pipe with locknuts.
The rear section of intermediate pipe connects to the tail pipe assembly via a flanged joint, sealed with a metal
gasket and secured with locknuts and studs.
The forward and rear sections are joined by a silencer. The silencer is fabricated from stainless steel sheet to form
the body of the silencer. An end plate closes each end of the silencer and is attached to the body with seam joints.
Perforated baffle tubes, inside the silencer, are connected to the inlet and outlet pipes on each end plate. Internal
baffle plates support the baffle tubes and, together with a stainless steel fibre packing, absorb combustion noise
as the exhaust gases pass through the silencer.
The intermediate pipe is attached by two brackets, positioned at each end of the silencer, and two mounting
rubbers to the chassis. The mounting rubber allows for ease of alignment and vibration absorption.
Tail pipe assembly
The tail pipe is of welded and fabricated construction. The tail pipe connects to the intermediate pipe with a
flanged joint secured with locknuts and sealed with a metal gasket. The pipe is shaped to locate above the rear
axle allowing clearance for axle articulation. The pipe is also curved to clear the left hand side of the fuel tank
which has a reflective shield to protect the tank from heat generated from the pipe.
A fabricated silencer is located at the rear of the tail pipe. The silencer is circular in section and is constructed from
stainless steel sheet. A baffle tube is located inside the silencer and the space around the baffle tube is packed
with a stainless steel fibre. The holes in the baffle tube allow the packing to further reduce combustion noise from
the engine. The tail pipe from the silencer is curved downwards at the rear of the vehicle and directs exhaust
gases towards the ground. The curved pipe allows the exhaust gases to be dissipated by the airflow under the
vehicle and prevents the gases from being drawn behind the vehicle.
The tail pipe is attached by a bracket, positioned forward of the silencer, and a mounting rubber to the chassis.
The mounting rubber allows ease of alignment and vibration absorption.
ProCarManuals.com

33CLUTCH
4
REPAIR Clutch pedal setting
1.Loosen both locknuts on master cylinder push
rod.
2.Check distance from lower edge of clutch pedal
to floor. Correct measurement is 140 mm (5.50
in) without floor mat.
3.Adjust pedal stop to obtain correct setting.
4.Adjust master cylinder push rod to obtain
approximately 1.5 mm (0.06 in) free play
between push rod and master cylinder piston.
5.Tighten push rod locknuts.
6.Check operation of clutch pedal and ensure that
there is minimum of 6 mm (0.25in) of free play
before pressure is felt.
7.Fit pedal box top cover and multiplug bracket
using a new gasket and secure with screws.
8.Connect multiplug and harness clip to pedal
bracket.
9.Bleed clutch hydraulic system.See
Adjustment.CYLINDER - CLUTCH SLAVE
Service repair no - 33.35.01
Remove
1.Disconnect pipe from slave cylinder.
CAUTION: Plug the connections.
2.Position container to catch spillage.
3.Remove 2 bolts securing slave cylinder to bell
housing.
4.Withdraw slave cylinder from bell housing and
push rod.
Refit
5.Clean ends of pipes, bell housing and slave
cylinder mating faces.
6.Lubricate end of push rod with Molybdenum
disulphide gease.
7.Locate slave cylinder to push rod and bell
housing.
8.Fit bolts and tighten to25 Nm (18 lbf.ft).
9.Connect clutch pipe to slave clyinder.
10.Bleed clutch system.See Adjustment.
ProCarManuals.com

MANUAL GEARBOX
1
ADJUSTMENT SPRINGS - GEAR LEVER BIAS
Service repair no - 37.16.26
Check
NOTE: The purpose of this adjustment is
to set both bolts so that the bias spring
legs apply equal pressure on both ends of
the gear lever cross pin when 3rd or 4th gear is
engaged. This will ensure that when the gear lever
is in neutral, the gear change mechanism is
automatically aligned for 3rd or 4th gears.
1.Remove gear lever knobs.
2.Release and remove gear lever gaiter.
3.Select 3rd or 4th gear.
4.Adjust the two adjusting screws until both legs of
the spring are approximately 0.5 mm (0.02 in)
clear of cross pin in the gear lever.
5.Apply a light load to the gear lever in a RH
direction and adjust the LH adjusting screw
downwards until the LH spring leg just makes
contact with the cross pin.
6.Repeat the same procedure for the RH adjusting
screw.
7.Lower both adjusting screws equal amounts until
the radial play is just eliminated. Tighten lock
nuts.
8.Return gear lever to neutral position and move
gear lever across the gate several times. The
gear lever should return to the 3rd and 4th gate.
9.Fit gear lever gaiter.
10.Fit gear lever knobs.
ProCarManuals.com

37MANUAL GEARBOX
4
REPAIR MECHANISM AND HOUSING - GEAR SELECTOR
Service repair no - 37.16.37
Remove
1.Remove gear lever knobs.
2.Remove gearbox tunnel carpet.
3.Remove gear lever gaiter(s)
4.Release and remove insulation pad from around
gear levers.
5.Remove 2 screws securing relay/fuse panel and
collect 2 spacers.
6.Release bulkhead carpet from LH side of tunnel
and move aside.
7.Remove 13 screws securing tunnel cover.
8.Release and remove tunnel cover.
9.Remove 4 bolts securing gear change housing,
remove housing, remove and discard gasket.
10.Using a suitable piece of tubing located over
ends of bias spring, release both ends of bias
spring from ball pins.
11.Loosen locknuts and remove bias spring
adjusting screws.
12.Drift out roll pin, remove bias spring.
13.Remove nut and extension from lower gear
lever.
ProCarManuals.com

MANUAL GEARBOX
5
REPAIR
14.Remove bolt and special washer securing lower
gear lever in housing.
15.Carefully withdraw lower gear lever from the
housing ensuring that the spring loaded nylon
pad is retained during removal.
WARNING: Personal injury may result if
nylon pad is not retained.
16.Release nylon pad, recover spring.
Refit
17.Clean components, gear change housing and
mating face on remote housing.
18.Apply multi - purpose grease to ball pin and fit
spring and nylon pad.
19.Depress nylon pad against spring pressure,
position lower gear lever in housing with the
nylon pad facing away from bias spring location.
20.Fit lower gear lever retaining bolt and special
washer and tighten bolt to10 Nm (7 lbf.ft).
21.Fit upper gear lever to lower gear lever and
tighten nut to25 Nm (18 lbf.ft).
22.Drift new roll pin into housing.
23.Fit bias spring adjusting screws and locknuts.
24.Using a suitable piece of tubing, locate both
ends of bias spring over ball pins.
25.Fit new gasket to remote housing, position gear
change housing to remote housing and tighten
bolts to25 Nm (18 lbf.ft).26.Adjust bias springs.See Adjustment.
27.Fit and align tunnel cover, fit and tighten screws.
28.Secure bulkhead carpet to LH side of tunnel.
29.Position relay/fuse panel, fit spacers and tighten
screws.
30.Fit insulation pad around gear levers.
31.Fit gear lever gaiter(s).
32.Fit gearbox tunnel carpet.
33.Fit gear lever knobs.
ProCarManuals.com

37MANUAL GEARBOX
10
REPAIR
34.Pull handbrake cable through heel board.
35.Disconnect multiplug from speed sensor and
release harness from clip on transfer gearbox.
36.Remove retaining nut and release battery earth
lead from transfer gearbox.
37.Release body harness clips from bracket on top
of transfer gearbox.
38.Lower gearbox jack sufficiently to allow transfer
gearbox lever to clear tunnel.
39.Disconnect 2 Lucars from differential lock switch,
multiplug from reverse light switch and multiplug
from low ratio detect switch - if fitted and release
multiplug from bracket.
40.Remove bolt and release earth leads from RH
side of transfer gearbox.
41.Support the weight of the engine.
42.Remove 6 bolts securing clutch housing to
engine.
43.With assistance, remove gearbox from engine.
ProCarManuals.com