2002 LAND ROVER DISCOVERY coolant temperature

COOLING SYSTEM - V8
DESCRIPTION AND OPERATION 26-2-9
Viscous fan
1Coolant pump pulley drive attachment
2Fan blades
3Bi-metallic coil
4Body
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 the coolant pump drive pulley and secured to the pulley by a nut. The nut is positively
attached to a 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 coolant pump pulley and the coupling body. The drive plate and the
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'.
At low radiator temperatures, the fan operation is not required and the bi-metallic coil keeps the valve closed,
separating the silicone fluid from the drive plate. This allows the fan to 'freewheel' reducing the load on the engine,
improving fuel consumption and reducing noise generated by the rotation of the fan.
When the radiator temperature increases, the bi-metallic coil reacts and moves the valve, allowing the silicone fluid
to flow into the fluid chamber. The resistance to shear of the silicone fluid creates drag on the drive plate and provides
drive to the body and the fan blades.

COOLING SYSTEM - V8
26-2-10 DESCRIPTION AND OPERATION
Operation
Coolant flow - Engine warm up
Refer to illustration.

+ COOLING SYSTEM - V8, DESCRIPTION AND OPERATION, Cooling system coolant flow.
During warm-up the coolant pump moves fluid through the cylinder block and it emerges from the inlet manifold outlet
pipe. From the outlet pipe, the warm coolant flow is prevented from flowing through the radiator because the
thermostat is 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 returning from the radiator bottom hose.
At engine idle speed, the by-pass valve is closed only allowing the small flow through the sensing holes. As the engine
speed increases above idle, the greater flow and pressure from the pump overcomes the light spring and opens the
by-pass flow valve. The flow valve opens to meet the engines cooling needs at higher engine speeds and prevents
excess pressure in the system. With the thermostat closed, maximum flow is directed through the heater circuit.
The heater matrix acts as a heat exchanger reducing coolant temperature as it passes through the matrix. Coolant
emerges from the matrix and flows 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 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 into the cylinder block to
cool the cylinders.

COOLING SYSTEM - V8
DESCRIPTION AND OPERATION 26-2-11
Viscous fan operation
A = Cold, B = Hot
1Drive plate
2Fan body
3Clearance
4Valve plate
5Valve
6Bi-metallic coil7Fluid seals
8Ball race
9Fluid chamber
10Reservoir
11Return port
When the engine is off and the fan is not rotating, the silicone fluid stabilises within the fluid chamber and the reservoir.
The fluid levels equalise due to the return port in the valve plate being open between the fluid chamber and the
reservoir. In this condition, when the engine is started, silicone fluid is present in the fluid chamber and causes drag
to occur between the drive plate and the body. This causes the fan to operate initially when the engine is started.
As the fan speed increases, centrifugal force and a scoop formed on the fluid chamber side of the valve plate, pushes
the silicone fluid through the return port in the valve plate into the reservoir. As the fluid chamber empties, the drag
between the drive plate and body is reduced, causing the drive plate to slip. This reduces the rotational speed of the
fan and allows it to 'freewheel'.
When the coolant temperature is low, the heat emitted from the radiator does not affect the bi-metallic coil. The valve
remains closed, preventing fluid escaping from the reservoir into the fluid chamber. In this condition the fan will
'freewheel' at a slow speed.

COOLING SYSTEM - V8
26-2-12 DESCRIPTION AND OPERATION
As the coolant temperature increases, the heat emitted from the radiator causes the bi-metallic coil to tighten. This
movement of the coil moves the valve to which it is attached. The rotation of the valve exposes ports in the valve plate
which allow silicone fluid to spill into the fluid chamber. As the fluid flows into the clearance between the annular
grooves in the drive plate and body, drag is created between the two components. The drag is due to the viscosity
and shear qualities of the silicone fluid and cause the drive plate to rotate the body and fan blades.
As the coolant temperature decreases, the bi-metallic coil expands, rotating the valve and closing off the ports in the
valve plate. When the valve is closed, centrifugal force pushes silicone fluid through the return port, emptying the fluid
chamber. As the fluid chamber empties, the drag between the drive plate and the body is reduced and the body slips
on the drive plate, slowing the rotational speed of the fan.

COOLING SYSTEM - V8
26-2-14 ADJUSTMENTS
5.Release top hose from retaining lugs on the fan
cowl, leaving the hose to rest on the lugs.
6.Remove bleed screw from top hose.
l'A' From 03 MY
l'B' Up to 03 MY
7.Unclip the bleed hose from the battery box.
8.Remove expansion tank from its mounting
bracket. Slowly fill the expansion tank with
coolant, approx. 4 litres (7 pt).
9.Raise the expansion tank approx. 20 cm (8 in)
vertically, coolant will drain into the system.
10.Refill the coolant expansion tank until a steady
flow of coolant is emitted from the bleed hole.
11.Fit the bleed screw then, with the expansion
tank still raised, continue filling the system until
the coolant level reaches the base of the
expansion tank filler neck.12.Fit expansion tank filler cap, fit the expansion
tank to its mountings and clip the bleed hose to
the battery box.
13.Refit the top hose into its lugs on the fan cowl.
14.Start and run engine until normal operating
temperature is reached, and check for leaks.
15.Switch off engine and allow to cool.
16.Check for leaks and top-up coolant to cold level
mark on expansion tank

MANIFOLDS AND EXHAUST SYSTEMS - V8
DESCRIPTION AND OPERATION 30-2-5
Description
General
The inlet manifold on the V8 engine is located on the top of the engine, between the cylinders. The manifold directs
intake air into the cylinders. The intake air is mixed with fuel delivered by the injectors prior to ignition in the cylinders.
The inlet manifold comprises three separate aluminium castings.
Two exhaust manifolds are used, one for each bank of four cylinders. Each exhaust manifold allows combustion
gases from the cylinders to leave the engine and directs them into the exhaust system.
The exhaust system is connected to each exhaust manifold and merges into one pipe midway along the underside of
the vehicle. A catalytic converter (where fitted) is located in the front pipe from each manifold. A silencer is installed
midway along the system and a second tail silencer is located at the rear of the vehicle.
Inlet manifold
The inlet manifold comprises three aluminium castings; a lower manifold, an upper manifold and a plenum. The inlet
manifold is located on the top of the engine and feeds air into the cylinders.
Lower manifold
The lower manifold is a one piece machined aluminium casting which locates in the vee on the top of the engine and
is secured to each cylinder head with six bolts per head. A one piece coated metal gasket seals the lower manifold to
each cylinder head and also serves as a cover for the cylinder block.
Eight injectors are fitted into the lower manifold, four on each side. Each injector is sealed in the manifold with O-ring
seals and retained in position by the fuel rails. A fuel rail is attached to each side of the manifold and secured with two
bolts.
Eight air intake ports are cast and machined on the top of the manifold, each port directing intake air into one cylinder.
These ports mate with matching ports in the upper manifold and are sealed with a coated metal gasket between the
two manifolds.
A cavity at the front of the manifold collects coolant flow from the engine. A coolant outlet pipe is sealed and attached
to the front of the manifold and provides for coolant to flow through the cavity in the casting to the radiator top hose.
A smaller port in the manifold also allows coolant to flow from the cavity to the heater matrix. The lower manifold also
locates the Engine Coolant Temperature (ECT) sensor in a port in the front of the manifold.
Upper manifold
The upper manifold is a one piece machined aluminium casting. The manifold has eight ports on its lower face which
mate with the eight ports on the lower manifold. The joint between the upper and lower manifolds is sealed with a
coated metal gasket and secured with six bolts.
The manifold divides from the eight ports into eight branches, four on each side. Each set of four branches merge into
one gallery on each side of the manifold. Each gallery has an opening at its forward end which mates with the intake
plenum.
The upper manifold provides attachment for the Idle Air Control (IAC) valve and for brackets which retain pipes, plug
leads and throttle cables.

MANUAL GEARBOX - R380
REPAIRS 37-15
34.Remove 14 bolts securing gearbox to engine.
35.With assistance, remove gearbox from engine.
Refit
1.Clean gearbox to engine mating faces, dowels
and dowel holes.
2.Raise gear gearbox on jack and align to clutch
and engine.
3.Fit bolts securing gearbox to engine and
tighten to 45 Nm (33 lbf.ft).
4.Lubricate and fit new 'O' rings to oil cooling
pipe housing.
5.Position coolant pipe housing, fit bolts and
tighten to 25 Nm (18 lbf.ft).
6. If fitted: Secure harness in retaining clips,
connect Lucars to differential lock warning
switch and multiplug to neutral sensor.
7.Position breather pipes and secure 'P' clip with
bolt.
8.Using new sealing washers fit breather pipe
banjo bolts and tighten to 15 Nm (11 lbf.ft).
9.Connect oil temperature sensor Lucars and
reverse lamp switch multiplug.
10.Position low ratio selector cable to housing and
secure with 'C' washer and clevis pin.
11.Secure cable to fuel pipes with new cable ties.
12.Raise gearbox, ensuring gear change lever is
located in grommet.
13.Fit gearbox mountings and tighten bolts to 85
Nm (63 lbf.ft). 14.Fit nuts to mountings and tighten to 48 Nm (37
lbf.ft).
15.Remove 3 bolts securing support plate to
gearbox.
16.Position clutch slave cylinder and heat shield,
fit bolts and tighten to 25 Nm (18 lbf.ft).
17.Clean handbrake back plate and mating face.
18.Position handbrake back plate, fit bolts and
tighten to 75 Nm (46 lbf.ft).
19.Clean handbrake drum.
20.Fit handbrake drum and tighten retaining
screw.
21.Clean propeller shafts and mating faces.
22.Position propeller shafts, align to marks and
tighten bolts to 47 Nm (35 lbf.ft).
23.Clean exhaust silencer and tail pipe mating
faces.
24.Position silencer and secure on mountings,
using a new gasket align to tail pipe, fit nuts
and tighten to 25 Nm (18 lbf.ft).
25.Position rear cross member, fit bolts and
tighten to 25 Nm (18 lbf.ft).
26.Refill gearbox with oil.

+ MAINTENANCE, PROCEDURES,
Manual gearbox.
27.Refill transfer gearbox oil.

+ MAINTENANCE, PROCEDURES,
Transfer box.
28.Fit front exhaust pipe.

+ MANIFOLDS AND EXHAUST
SYSTEMS - V8, REPAIRS, Front pipe.
29.Fit gear lever extension, fit clamp bolt and
tighten to 25 Nm (18 lbf.ft).
30.Fit gear lever trim and gear change knob.
31.Connect battery earth lead.
32. Fit battery cover and cooling fan cover and
secure fixings.

HEATING AND VENTILATION
DESCRIPTION AND OPERATION 80-3
Description
General
The heating and ventilation system controls the temperature and distribution of air supplied to the vehicle interior. The
system consists of an air inlet duct, heater assembly, distribution ducts and a control panel. An outlet vent is
incorporated at the rear of the cabin. Some diesel models also incorporate a fuel burning heater (FBH) system in the
engine coolant supply to the heater assembly.
Fresh or recirculated air flows into the heater assembly from the inlet duct. An electrical variable speed blower in the
inlet duct, and/or ram effect, forces the air through the system. Depending on the settings on the control panel, the air
is then heated and supplied through the distribution ducts to fascia and floor level outlets.