1995 LAND ROVER DISCOVERY engine coolant

26COOLING SYSTEM
2
DESCRIPTION AND OPERATION COOLANT CIRCULATION
Operation
When the engine is started from cold the thermostat
prevents any coolant circulation through the radiator
by closing off the top hose. During the engine warm
up period, the water pump, pumps coolant around the
cylinders to the rear of the cylinder block along the
main galleries in both cylinder banks. At the rear of
the cylinder block the coolant rises through a large
port in each cylinder head/block joint face, and then
flows forward to connect with ports at the front of the
inlet manifold. From the manifold the coolant is carried
by an external pipe to the heater unit and from the
heater through another external pipe to the pump
inlet.The coolant circulation through the cylinder block and
heads, does not change when normal running
temperature is reached and the thermostat opens. But
with the thermostat open, coolant flows through the
top hose to the radiator where it is cooled and drawn
back into the pump via the bottom hose.

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DESCRIPTION AND OPERATION Plenum chamber heating
Air entering the plenum chamber is heated by a flow
of coolant from the inlet manifold which returns
through a long hose, to the top right corner of the
radiator.
1. Hot water supply
2. Cold return to radiatorVISCOUS 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 through the medium of a special
'silicone fluid' injected into the unit during
manufacture.
1. Drive in from water pump spindle
2. Drive out to fan blades
3. Bi-metal

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FAULT DIAGNOSIS ENGINE OVERHEATING
Before conducting any cooling system diagnosis:
See
Description and operation, Engine Cooling
1.Is coolant level correct?
NO - Allow engine to cool, top up level to
expansion tank seam.
YES - Continue.
2.Is drive belt tension correct?
NO -
See ENGINE, Repair, Drive Belt -
Check Tension
YES - Continue.
3.Is ignition timing correct?
NO -
See ELECTRICAL, Adjustment,
Ignition Timing
YES - Continue.
4.Is coolant in radiator frozen?
YES - Slowly thaw and drain system.
See
Adjustment, Coolant Requirements
NO - Continue.
5.Is air flow through radiator restricted or blocked?
YES - Apply air pressure from engine side of
radiator to clear obstruction.
NO - Continue.
6.Are there any external leaks, from water pump,
engine gaskets or the heater unit?
YES - Investigate and rectify.
See Adjustment,
Coolant Requirements
NO - Continue.
7.Are fan blades fitted correct way round, concave
side towards engine?
NO - Rectify.
YES - Continue.8.Is viscous unit operating correctly?
See
Description and operation, Viscous Fan
NO - Renew.See Repair, Viscous
Coupling, Fan Blades, Pulley and Fan
Cowl
YES - Carry out a pressure test on radiator cap
and system. Check thermostat type,
operation and correct fitting
See Repair,
Thermostat
If pressure test leads you to suspect coolant
leakage across gaskets, go to check 11,
otherwise: Continue.
9.Are the air conditioning fans operating correctly?
See Electrical Trouble Shooting Manual.K5
NO - Rectify.
YES - Continue.
10.Is temperature sender and gauge giving
accurate readings?
NO - Substitute parts and compare readings.
YES - Continue.
11.Carry out cylinder pressure test to determine if
pressure is leaking into cooling system causing
over pressurising and loss of coolant.
If problem is not diagnosed, check the coolant system
for engine oil contamination and engine lubrication
system for coolant contamination.
If the coolant only, or both systems are contaminated,
suspect cylinder head gaskets or radiator.
If only the lubrication stystem is contaminated with
coolant, suspect inlet manifold or front cover gaskets.

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ADJUSTMENT COOLANT REQUIREMENTS
Frost precautions and engine protection.
Cooling systemMUST ALWAYSbe filled and
topped-up with solution of water and anti-freeze,
winter and summer.NEVERuse water alone, this
may corrode aluminium alloy.
CAUTION: Do not use salt water otherwise
corrosion will occur. In certain territories
where only available natural water supply
has some salt content use only rain or distilled
water.
Recommended solutions
Anti-freeze:Universal anti-freeze or permanent type
ethylene base, without methanol, containing a suitable
inhibitor for aluminium engines and engine parts.
Use one part of anti-freeze to one part of water.
Anti-freeze can remain in the cooling system and will
provide adequate protection for two years provided
that specific gravity of coolant is checked before onset
of second winter and topped-up with new anti-freeze
as required.
Vehicles leaving factory have cooling system filled
with 50% solution of anti-freeze and water. This gives
protection against frost down to minus 36°C (minus
33°F). Vehicles so filled are identified by a label
affixed to radiator.
NOTE: Should ambient temperatures be
below that stated above refer to
Anti-Freeze Data in Recommended
Lubricants, Fluids and Capacities in Section 09.
Instructions in chart must be strictly adhered to
before driving vehicle.
After the second winter the system should be drained
and thoroughly flushed. Before adding new anti-freeze
examine all joints and replace defective hoses to
make sure that the system is leakproof.
See the 'Recommended Lubricants Fluids and
Capacities' for protection quantities.
See
LUBRICANTS, FLUIDS AND CAPACITIES,
Information, Recommended Lubricants and
Fluids
COOLANT
Service repair no - 26.10.01
Draining
WARNING: Do not remove expansion tank
filler cap when engine is hot. The cooling
system is pressurised and personal
scalding could result.
See coolant requirements before refilling system.
1.Remove expansion tank filler cap by slowly
turning it anti-clockwise, pause to allow pressure
to escape. Continue turning it in same direction
and remove.
2.Remove radiator filler plug and 'O' ring to assist
drainage.

26COOLING SYSTEM
2
ADJUSTMENT 3.Disconnect bottom hose from radiator. Drain
coolant into a clean container. Reconnect bottom
hose, re-tighten hose clamp.
NOTE: It is not possible to drain all coolant
retained in heater system. It is not
desirable to flush through system, after
draining.
4.Remove engine drain plugs, one each side of
cylinder block, beneath exhaust manifolds. Drain
coolant, refit and tighten plugs.
5.Pour correct solution of water and anti-freeze
into expansion tank until radiator is full.
6.Start engine, run it until normal operating
temperature is attained, topping up as
necessary.
7.Refit radiator filler plug and 'O' ring, with new 'O'
ring if required. Tighten to
6 Nm.
8.Fit expansion tank filler cap.
9.Allow engine to cool, check coolant level. Finally
top up expansion tank until level reaches seam
of expansion tank.

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REPAIR EXPANSION TANK
Service repair no - 26.15.01
Remove
WARNING: Do not remove expansion tank
filler cap when engine is hot. The cooling
system is pressurised and personal
scalding could result.
1.Remove expansion tank filler cap by first turning
it slowly anti-clockwise, pause to allow pressure
to escape. Continue turning in same direction
and lift off.
2.Disconnect two hoses from bottom of expansion
tank, allowing coolant to drain into a suitable
container.
3.Remove three fixing bolts, remove expansion
tank.
Refit
4.Reverse removal procedure.
5.Replenish cooling system.
6.Check for leaks around all hose connections.VISCOUS COUPLING, FAN BLADES, PULLEY AND
COWL
Service repair no - 26.25.19 - Viscous coupling
and fan assembly
Service repair no - 26.25.03 - Water pump pulley
Service repair no - 26.25.05 - Fan blades
Special tools:
LRT-12-093
LRT-12-094 - Viscous coupling removal
Remove
1.Disconnect battery negative lead.
NOTE: 4.0 V8 only:
Release coolant hose from cooling fan upper
cowl.
2.Release 2 clips securing cooling fan upper cowl.
Remove cowl.

26COOLING SYSTEM
4
REPAIR RADIATOR
Service repair no - 26.40.01
Remove
1.Drain cooling system.
See Adjustment,
Coolant
2.Remove viscous coupling and fan assembly.
See Viscous Coupling, Fan Blades, Pulley
and Fan Cowl
3.Release 2 clips and remove fan cowl.
4.Disconnect radiator top hoses.
5.Disconnect four transmission and engine oil
cooler connections to radiator end tanks. Note oil
spillage will occur when connections are
loosened. Blank off exposed oil connections.
6.Disconnect transmission oil temperature sensor.
7.Remove radiator securing brackets from each
side.
8.Remove radiator unit by lifting from its location.
Check condition of rubber mounting pads.Refit
9.Reverse removal procedure.
10.Clean unions and apply sealant.
11.Lubricate new 'O' rings before fitting.
12.Check radiator sealing strips are securely
located.
13.Transfer oil cooler adaptors if fitting new radiator.
14.Ensure that oil cooler connections are tightened
to
30 Nm.before fitting fan blades and cowl.
15.Clean coolant/oil spillage from vehicle.
16.Check all connections for coolant/oil leaks.

26COOLING SYSTEM
6
REPAIR WATER PUMP
Service repair no - 26.50.01
Remove
WARNING: Disconnect battery negative
terminal to prevent engine being started
before removing or adjusting drive belts.
1.Drain engine cooling system.
See Adjustment,
Coolant
2.Remove fan blades and pulley.See Viscous
Coupling, Fan Blades, Pulley and Fan Cowl
3.Disconnect inlet hose from water pump.
4.Remove water pump bolts.
5.Remove water pump and joint washer.
Refit
6.Lightly grease new joint washer, position on
timing cover.
7.Clean threads of all long bolts and coat with
Loctite 572 thread lubricant-sealant.
8.Locate water pump in position. Tighten
remaining water pump housing bolts evenly to
28 Nm.
9.Reverse removal procedure. 1 to 3.
10.Check for coolant leaks around all hose
connections and joint faces.