1999 LAND ROVER DISCOVERY radiator

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.

COOLING SYSTEM - V8
DESCRIPTION AND OPERATION 26-2-9
Viscous fan
1Coolant pump pulley drive attachment
2Fan blades3Bi-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.
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
ADJUSTMENTS 26-2-13
ADJUST ME NTS
Drain and refill
$% 26.10.01
WARNING: Since injury such as scalding could
be caused by escaping steam or coolant, do not
remove the filler cap from the coolant expansion
tank while the system is hot.
Drain
1.Visually check engine and cooling system for
signs of coolant leaks.
2.Examine hoses for signs of cracking, distortion
and security of connections.
3.Position drain tray to collect coolant.
4.Remove expansion tank filler cap.
LH side
RH side
5.Remove drain plugs from LH and RH sides of
cylinder block and allow cooling system to
drain.6.Disconnect bottom hose from radiator and
allow cooling system to drain.
7.Disconnect top hose from thermostat and
position open end of hose below level of
coolant pump inlet, to allow coolant to drain
from the system.
Refill
1.Flush system with water under low pressure.
Do not use water under high pressure as it
could damage the radiator.
2.Apply Loctite 577 to cylinder block drain
plugs.Fit drain plugs to cylinder block and
tighten to 30 Nm (22 lbf.ft).
3.Connect bottom hose to radiator and top hose
to thermostat housing. Secure with hose clips.
4.Prepare coolant to required concentration.

+ CAPACITIES, FLUIDS,
LUBRICANTS AND SEALANTS, Anti-Freeze
Concentration.

COOLING SYSTEM - V8
REPAIRS 26-2-15
REPAIRS
Fan - viscous
$% 26.25.19
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery earth lead.
3.Remove upper fan cowl.
4.Remove viscous fan using tool LRT-12-093
and tool LRT-12-094.
RH thread.
Refit
1.Position viscous fan and tighten using tool
LRT-12-093 and tool LRT-12-094.
2.Fit upper fan cowl.
3.Connect battery earth lead.
4.Fit battery cover and secure fixings.
Radiator
$% 26.40.01
Remove
1.Remove viscous fan.

+ COOLING SYSTEM - V8, REPAIRS,
Fan - viscous.
2.Drain cooling system.

+ COOLING SYSTEM - V8,
ADJUSTMENTS, Drain and refill.
3.Remove 2 screws and remove lower of fan
cowl.
4.Release clip and disconnect bottom hose from
thermostat housing.
5.Release clip and disconnect top hose from
radiator.
6.Remove clip and disconnect bleed hose from
radiator.
7.Remove front grille.

+ EXTERIOR FITTINGS, REPAIRS,
Grille - front - up to 03MY.

COOLING SYSTEM - V8
26-2-16 REPAIRS
8.Remove 6 scrivets and remove LH and RH air
deflectors from front panel. Disconnect
multiplug of gearbox oil temperature sensor
(arrowed).
9.Remove nut and move horn aside. 10.Remove 2 bolts securing radiator LH and RH
upper mounting brackets to body panel and
remove brackets.
11.Remove 4 screws securing air conditioning
condenser LH and RH upper mounting
brackets to condenser.
12.Remove brackets with rubber mounts from
radiator extension brackets.
13.Position absorbent cloth under each cooler
hose to collect oil spillage.
14.Push against coupling release rings and
disconnect hoses from gearbox oil cooler.
CAUTION: Always fit plugs to open
connections to prevent contamination.
15. If fitted: Push against coupling release rings
and disconnect hoses from engine oil cooler.

COOLING SYSTEM - V8
REPAIRS 26-2-17
16.Remove radiator assembly.
17.Release clip and remove bottom hose from
radiator.
18.Remove 2 bolts and remove extension
brackets from radiator.
19.Remove 2 captive nuts from radiator.
20.Remove 2 screws and remove gearbox oil
cooler from radiator.
21. If fitted: Remove 2 screws and remove engine
oil cooler from radiator.
22.Remove 2 rubber mountings from radiator.
23.Remove sealing strip from bottom of radiator.
24.Remove 2 cowl retaining clips from radiator. Refit
1.Fit cowl retaining clips to radiator.
2.Fit sealing strip to radiator.
3.Fit rubber mountings to radiator.
4.Fit gearbox oil cooler to radiator and secure
with screws.
5. If fitted: Fit engine oil cooler to radiator and
secure with screws.
6.Fit captive nuts to radiator.
7.Fit extension brackets to radiator and secure
with bolts.
8.Fit bottom hose to radiator and secure with clip.
9.Fit radiator and engage lower mountings in
chassis.
10.Ensure connections are clean, then secure
hoses to oil coolers.
11.Fit air conditioning condenser brackets and
secure with screws.
12.Fit radiator upper mounting brackets and
secure with bolts.
13.Fit LH horn and secure with nut.
14.Fit air deflectors and secure with scrivets.
15.Connect multiplug of gearbox oil temperature
sensor.
16.Fit front grille.

+ EXTERIOR FITTINGS, REPAIRS,
Grille - front - up to 03MY.
17.Connect bottom hose to thermostat housing
and secure with clip.
18.Connect top hose to radiator and secure with
clip.
19.Connect bleed hose to radiator and fit clip.
20.Fit lower fan cowl and secure with screws.
21.Fit viscous fan.

+ COOLING SYSTEM - V8, REPAIRS,
Fan - viscous.
22.Top up gearbox oil.
23.Top up engine oil.
24.Refill cooling system.

+ COOLING SYSTEM - V8,
ADJUSTMENTS, Drain and refill.