1999 LAND ROVER DISCOVERY oil type

COOLING SYSTEM - V8
26-2-6 DESCRIPTION AND OPERATION
Description
General
The cooling system used on the V8 engine is a pressure relief by-pass type system which allows coolant to circulate
around the cylinder block and the heater circuit when the thermostat is closed. With coolant not passing through the
radiator, this promotes faster heater warm-up which in turn improves passenger comfort.
A coolant pump is located in a housing at the front of the engine and is driven by a drive belt. The pump is connected
into the coolant passages cast in the cylinder block and pumps coolant from the radiator through the cylinder block.
A viscous fan is attached by means of a nut to the coolant pump pulley drive spindle. The fan draws air through the
radiator to assist in cooling when the vehicle is stationary. The fan rotational speed is controlled relative to the running
temperature of the engine by a thermostatic valve regulated by a bi-metallic coil.
The cooling system uses a 50/50 mix of anti-freeze and water.
Thermostat housing
A plastic thermostat housing is located behind the radiator. The housing has three connections which locate the
radiator bottom hose, top hose and coolant pump feed hose. The housing contains a wax element and a spring loaded
by-pass flow valve.
Thermostat - Main valve
The thermostat is used to maintain the coolant at the optimum temperature for efficient combustion and to aid engine
warm-up. The thermostat is closed at temperatures below approximately 82°C (179°F). When the coolant
temperature reaches approximately 82°C the thermostat starts to open and is fully open at approximately 96°C
(204°F). In this condition the full flow of coolant is directed through the radiator.
The thermostat is exposed to 90% hot coolant from the engine on one side and 10% cold coolant returning from the
radiator bottom hose on the other side.
Hot coolant from the engine passes from the by-pass pipe through four sensing holes in the flow valve into a tube
surrounding 90% of the thermostat sensitive area. Cold coolant returning from the engine, cooled by the radiator,
conducts through 10% of the sensitive area.
In cold ambient temperatures, the engine temperature is raised by approximately 10°C (50°F) to compensate for the
heat loss of 10% exposure to the cold coolant returning from the bottom hose.
By-pass flow valve
The by-pass flow valve is held closed by a light spring. It operates to further aid heater warm-up. When the main valve
is closed and the engine speed is at idle, the coolant pump does not produce sufficient flow and pressure to open the
valve. In this condition the valve prevents coolant circulating through the by-pass circuit and forces the coolant through
the heater matrix only. This provides a higher flow of coolant through the heater matrix to improve passenger comfort
in cold conditions.
When the engine speed increases above idle the coolant pump produces a greater flow and pressure than the heater
circuit can take. The pressure acts on the flow valve and overcomes the valve spring pressure, opening the valve and
limiting the pressure in the heater circuit. The valve modulates to provide maximum coolant flow through the heater
matrix and yet allowing excess coolant to flow into the by-pass circuit to provide the engine's cooling needs at higher
engine rev/min.

COOLING SYSTEM - V8
DESCRIPTION AND OPERATION 26-2-7
Inlet manifold - Cooling connections
Coolant leaves the cylinder block via an outlet pipe attached to the front of the air intake manifold. The pipe is
connected to the thermostat housing and the radiator by a branch hose off the radiator top hose.
Hot coolant from the engine is also directed from the inlet manifold via pipes and hoses into the heater matrix. Coolant
is circulated through the heater matrix at all times when the engine is running.
A further tapping from the inlet manifold supplies coolant to the throttle housing via a hose. The coolant circulates
through a plate attached to the bottom of the housing and is returned through a plastic bleed pipe to an expansion
tank. The hot coolant heats the air intake of the throttle housing preventing ice from forming.
An Engine Coolant Temperature (ECT) sensor is fitted in the inlet manifold adjacent to the manifold outlet pipe. The
sensor monitors coolant temperature emerging from the engine and sends signals to the ECM for engine
management and temperature gauge operation.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
Expansion tank
The expansion tank is located in the engine compartment. The tank is made from moulded plastic and attached to
brackets on the right hand inner wing. A maximum coolant when cold level is moulded onto the tank.
Excess coolant created by heat expansion is returned to the expansion tank from the radiator bleed pipe at the top of
the radiator. An outlet pipe is connected into the pump feed hose and replaces the coolant displaced by heat
expansion into the system when the engine is cool.
The expansion tank is fitted with a sealed pressure cap. The cap contains a pressure relief valve which opens to allow
excessive pressure and coolant to vent through the overflow pipe. The relief valve opens at a pressure of 1.4 bar (20
lbf.in
2) and above.
Heater matrix
The heater matrix is fitted in the heater assembly inside the passenger compartment. Two pipes pass through the
bulkhead into the engine compartment and provide coolant flow to and from the matrix. The pipes from the bulkhead
are connected to the matrix, sealed with 'O' rings and clamped with circular rings.
The matrix is constructed from aluminium with two end tanks interconnected with tubes. Aluminium fins are located
between the tubes and conduct heat away from the hot coolant flowing through the tubes. Air from the heater
assembly is warmed as it passes through the matrix fins. The warm air is then distributed into the passenger
compartment as required.

+ HEATING AND VENTILATION, DESCRIPTION AND OPERATION, Description.When the engine is
running, coolant from the engine is constantly circulated through the heater matrix.
Radiator
The 45 row radiator is located at the front of the vehicle. The cross-flow type radiator is manufactured from aluminium
with moulded plastic end tanks interconnected with tubes. Aluminium fins are located between the tubes and conduct
heat from the hot coolant flowing through the tubes, reducing the cooling temperature as it flows through the radiator.
Air intake from the front of the vehicle when moving carries 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 and bleed pipe. A connection at
the bottom of the radiator allows for the attachment of the bottom hose to the thermostat housing.
Two smaller radiators are located in front of the cooling radiator. The lower radiator provides cooling of the gearbox
oil and the upper radiator provides cooling for the engine oil.

+ MANUAL GEARBOX - R380, DESCRIPTION AND OPERATION, Description.

+ AUTOMATIC GEARBOX - ZF4HP22 - 24, DESCRIPTION AND OPERATION, Description.

+ ENGINE - V8, DESCRIPTION AND OPERATION, Description.
Pipes and hoses
The coolant circuit comprises flexible hoses and metal formed pipes which direct 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 is fitted
to each cylinder bank in the cylinder block. These are used to drain the block of coolant.

CLUTCH - V8
33-2-6 DESCRIPTION AND OPERATION
Description
General
The clutch system is a conventional diaphragm type clutch operated by a hydraulic cylinder. The clutch requires no
adjustment to compensate for wear.
Hydraulic clutch
The hydraulic clutch comprises a master cylinder, slave cylinder and a hydraulic reservoir, which is also shared with
the braking system. The master and slave cylinders are connected to each other hydraulically by plastic and metal
pipes. The plastic section of the pipe allows ease of pipe routing and also absorbs engine movements and vibrations.
The master cylinder comprises a body with a central bore. Two ports in the body connect the bore to the hydraulic
feed pipe to the slave cylinder and the brake/clutch fluid reservoir. A piston is fitted in the bore and has an external
rod which is attached to the clutch pedal with a pin. Two coiled springs on the clutch pedal reduce the effort required
to depress the pedal.
The master cylinder is mounted on the bulkhead in the engine compartment and secured with two bolts. The cylinder
is connected to the shared brake/clutch reservoir on the brake servo by a braided connecting hose.
The slave cylinder is located on the left hand side of the gearbox housing and secured with two bolts. A heat shield
protects the underside of the cylinder from heat generated from the exhaust system. The slave cylinder comprises a
cylinder with a piston and a rod. A port in the cylinder body provides the attachment for the hydraulic feed pipe from
the master cylinder. A second port is fitted with a bleed nipple for removing air from the hydraulic system after
servicing. The piston rod locates on a clutch release lever located in the gearbox housing. The rod is positively
retained on the release lever with a clip.
Clutch mechanism
The clutch mechanism comprises a flywheel, drive plate, pressure plate, release lever and a release bearing. The
clutch mechanism is fully enclosed at the rear of the engine by the gearbox housing.
A clutch release bearing sleeve is attached in the gearbox housing with two bolts and located on two dowels. A spigot
with a ball end is formed on the release bearing sleeve and provides a mounting and pivot point for the clutch release
lever. A dished pivot washer is located on the ball of the spigot. When the release lever is located on the ball, the pivot
washer seats against the rear face of the release lever. A spring clip is located on the lever and the pivot washer and
secures the lever on the spigot. A small bolt retains the spring clip in position.
The release lever is forked at its inner end and locates on the clutch release bearing carrier. The outer end of the
release lever has a nylon seat which locates the slave cylinder piston rod. A second nylon seat, positioned centrally
on the release lever, locates on the ball spigot of the release bearing sleeve and allows the release lever to pivot freely
around the ball.
The clutch release bearing locates on the clutch release lever and the release bearing sleeve. The bearing is retained
on a carrier which has two flats to prevent the carrier rotating on the release lever. A clip retains the release lever on
the carrier. The bearing and carrier are not serviceable individually.
Flywheel
The flywheel is bolted to a flange on the rear of the crankshaft with six bolts. A dowel on the crankshaft flange ensures
that the flywheel is correctly located. A ring gear is fitted on the outside diameter of the flywheel and seats against a
flange. The ring gear is an interference fit on the flywheel and is installed by heating the ring and cooling the flywheel.
The ring gear is a serviceable item and can be replaced if damaged or worn.
The operating face of the flywheel is machined to provide a smooth surface for the drive plate to engage on. Three
dowels and six threaded holes provide for the location and attachment of the pressure plate. The flywheel is balanced
to ensure that it does not produce vibration when rotating. A machined slot, with a series of holes within the slot, is
located on the engine side of the flywheel. The slot accommodates the tip of the crankshaft position sensor which is
used by the Engine Control Module (ECM) for engine management.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.

REAR AXLE
51-2 DESCRIPTION AND OPERATION
Description
General
The rear axle consists of an axle casing with a differential unit attached to the right of the vehicle centre line. A wheel
hub is installed in each end of the axle casing and connected to the differential unit by a drive shaft.
Axle casing
The axle casing is of welded construction, with brackets on the casing exterior for attachment to the rear suspension.
A differential cover on the rear of the axle casing contains an oil level plug for checking and replenishment of the
differential unit lubricating oil. A magnetic drain plug is installed on the underside of the axle casing.
The interior of the axle casing is ventilated through a breather tube inserted in a red plastic sleeve in the top of the
casing. The open end of the breather tube is located between the chassis and the left rear wheelarch.
Differential unit
The differential unit is of the spiral bevel type, lubricated by splash oil. The unit consists of a differential carrier
attached to a pinion housing. In the pinion housing, the pinion is splined to a pinion flange which is secured with a bolt
and washer. An oil seal prevents leakage past the pinion flange.
Centralising peg
The centralising peg is a press fit in the centre of the pinion flange and provides a positive location for the rear
propellor shaft to ensure it is centralised with the flange.

FRONT AXLE
54-2 DESCRIPTION AND OPERATION
Description
General
The front axle consists of an axle casing with a differential unit attached to the right of the vehicle centre line. A wheel
hub is installed in a steering knuckle at each end of the axle casing and connected to the differential unit by a drive
shaft.
Axle casing
The axle casing is of welded construction, with brackets on the casing exterior for attachment to the front suspension.
Yokes at each end of the casing incorporate upper and lower ball joints for attachment of the steering knuckles.
A differential cover on the front of the axle casing contains an oil level plug for checking and replenishment of the
differential lubricating oil. A magnetic drain plug is installed on the underside of the casing. An oil seal is installed in
each end of the axle casing to prevent leakage past the drive shafts.
The interior of the axle casing is ventilated through a breather tube inserted in a red plastic sleeve in the top of the
casing. The open end of the breather tube is located in the left rear corner of the engine compartment.
Differential unit
The differential unit is of the spiral bevel type, lubricated by splash oil. The unit consists of a differential carrier
attached to a pinion housing. In the pinion housing, the pinion is splined to a drive flange which is secured with a bolt
and washer. An oil seal prevents leakage past the drive flange.
Steering knuckle
The steering knuckles are mounted on upper and lower ball joints in the yokes at the end of the axle casing. A tension
collet, in the lower mounting point of each steering knuckle, accommodates manufacturing tolerances to enable the
correct tightening of both ball joints. Lugs are incorporated on the steering knuckles for attachment of the steering
system drag link and track rod.

FRONT AXLE
DESCRIPTION AND OPERATION 54-3
Wheel hub
Section through wheel hub
1Drive shaft
2Axle casing
3Gaiter
4Upper ball joint
5Constant velocity joint
6Steering knuckle
7Hub bearing
8Hub flange9Wheel stud
10Stake nut
11ABS sensor ring
12Tension collet
13Lower ball joint
14Securing bands
15Shield
16Oil seal
Each wheel hub consists of a hub flange pressed into a hub bearing.
The hub flange is splined to accept the constant velocity joint of the drive shaft, which is secured to the hub flange
with a stake nut. Five studs are installed in the hub flange for the wheel nuts and a threaded hole is provided for the
brake disc securing screw.
The outer race of the hub bearing is bolted to the steering knuckle. The hub bearing is a sealed unit which contains
twin opposed roller bearings, pre-packed with grease during manufacture. A toothed ABS sensor ring is integrated
into the inner race of the hub bearing. An opening in the outer race of the hub bearing accommodates the ABS sensor.
Drive shaft
Each drive shaft consists of a solid rod, splined at both ends, with a constant velocity joint installed on the outboard
end. A shield is incorporated onto each rod to protect the oil seals in the axle casing. The constant velocity joint is of
the ball and socket type. A shaft on the constant velocity joint is splined to the hub flange. The constant velocity joint
is pre-packed with grease and protected by a gaiter. Two securing bands retain the gaiter in position.

REAR SUSPENSION
DESCRIPTION AND OPERATION 64-7
Coil Spring Specifications – Models up to 03 Model Year
The rear coil springs are of the variable rate type and are manufactured from silicon manganese 16.5 mm (0.65 in.)
diameter bar. Each spring has 9 coils and a free length of 385 mm (15.1 in.). The variable rate of the spring is achieved
by the active coils at one end being closer together. The rear coil spring is identified by a purple stripe painted on a
number of coils.
Coil Spring Specifications – Models From 03 Model Year
The introduction of the 03MY vehicle introduced a range of additional rear coil spring fitments. These were introduced
as a package to optimise vehicle trim heights.
The coil springs are manufactured from silicon manganese 16.35 mm (0.64 in.) diameter bar for springs on five seater
models and 16.57 mm (0.65 in.) diameter bar on seven seater models. The following spring data table shows the
colour codes, number of coils and spring free length.
Spring Data
The following table shows spring fitment applicability.
Spring Fitment Applicability
Watts linkage
A Watts linkage is used to ensure that the rear axle remains centrally located. The Watts linkage comprises two
transverse links and a pivot housing. The transverse links and pivot housing allow the rear axle to move vertically
without any transverse movement.
The transverse links are made from fabricated and welded steel. Each transverse link has a bush press fitted into a
housing at one end. The opposite end has a forked bracket with two cross holes.
The pivot housing is made from cast iron. Three bushes are press fitted in the housing, one in the centre and one at
each end.
The pivot housing is located in a fabricated bracket centrally located on the rear of the axle. The central bush of the
pivot housing is secured in the bracket with a bolt and locknut. Fabricated brackets on each chassis longitudinal
provide for the attachment of each transverse link. Each link is secured through its bush with a bolt and locknut. The
forked end of each link locates over the bushes at each end of the pivot housing and is secured with a bolt and locknut.
The attachment bolts for each link are coated with a clear, dry wax which reduces friction on the bolt and allows the
correct torque to be applied to the clamping of the bushes. The bolts can be re-used, but if bolt replacement is
necessary the correct bolt with the wax coating must be used.
Colour Code Total No. of Coils Free Length Model
Brown/Orange 8.73 384.7 mm (15.14 in) 5 Seat
Grey/Orange 8.73 392 mm (15.43 in) 5 Seat
Yellow/Grey 8.73 376.6 mm (14.82 in) 5 Seat
Pink/Grey 8.73 400.3 mm (15.75 in) 5 Seat
Blue/Grey 9.10 387.8 mm (15.26 in) 7 Seat
Green/Grey 9.10 395.2 mm (15.55 in) 7 Seat
White/Grey 9.10 380.6 mm (14.98 in) 7 Seat
Left Hand Drive Right Hand Drive
Both Sides RH Side LH Side
Brown/Orange Grey/Orange Yellow/Grey
Grey Orange Pink/Grey Brown/Orange
Blue/Grey Green/Grey White/Grey

REAR SUSPENSION
64-8 DESCRIPTION AND OPERATION
Anti-roll bar
The anti-roll bars fitted differ between ACE and non-ACE vehicles. On non-ACE vehicles a conventional 'passive' anti-
roll bar is used. On ACE vehicles an 'active' torsion bar is used. Both types are attached to the tubular cross-member
at the rear of the chassis with mounting rubbers and clamp plates. The clamp plates locate in fabricated brackets
attached to the tubular cross-member and secured with bolts.
Each end of the anti-roll bar is attached to an anti-roll bar link. Each link has a spherical bearing attached at each end.
One end is attached to a bracket on the axle and secured with a locknut. The opposite end attaches through a hole
in the anti-roll bar and is also secured with a locknut. On 'active' torsion bars, the RH anti-roll bar link is attached to a
long arm which in turn is attached to the anti-roll bar.
Passive anti-roll bar
The passive anti-roll bar is a conventional anti-roll bar which opposes axle movement, reducing the effects of lateral
forces on the vehicle body.
With the conventional passive anti-roll bar, axle movement is opposed by the anti-roll bar through links attached to
the axle casing and each end of the anti-roll bar.
On vehicles with coil springs (no SLS fitted) the anti-roll bar is manufactured from 19 mm (0.74 in.) diameter spring
steel bar.
On vehicles with air springs (SLS fitted) the anti-roll bar is manufactured from 29 mm (1.14 in.) diameter spring steel
bar.
Active torsion bar

+ FRONT SUSPENSION, DESCRIPTION AND OPERATION, Description - ACE.The 'active' torsion bar is
used in conjunction with the ACE system to control body roll and directional stability giving a reduction of the effects
of lateral forces on the vehicle body over a conventional 'passive' anti-roll bar.
The torsion bar opposes axle movement by the application of a hydraulic force to oppose the lateral forces through
links attached to the axle casing and each end of the bar. The torsion bar is made from 35 mm (1.4 in.) diameter spring
steel. One end is fitted with an arm which is operated by a hydraulic actuator to oppose corning forces.