engine coolant LAND ROVER DEFENDER 1999 Service 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.
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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.
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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’.
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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.
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COOLING SYSTEM
1
ADJUSTMENT DRAIN AND REFILL
Service repair no - 26.10.01
WARNING: Hot coolant
Drain
1.Remove engine acoustic cover.
2.Visually check engine and cooling system for
signs of coolant leaks.
3.Examine hoses for signs of cracking, distortion
and security of connections.
4.Position drain tray to collect coolant.
5.Remove expansion tank filler cap.
6.Loosen clip screws securing air inlet hose to
intercooler and inlet manifold, release and
remove hose.
7.Release clip and disconnect bottom hose from
radiator.
8.Allow cooling system to drain.
9.Disconnect bottom hose from radiator.Refill
1.Flush system with water under low pressure.
2.Do not use water under high pressure as it could
damage the radiator.
3.Connect bottom hose to radiator and secure
hose with clip.
4.Prepare coolant to required concentration.
5.Position heater temperature control to maximum
hot position.
6.Remove bleed screw from top hose.
7.Fill system slowly through coolant expansion
tank until a steady flow of coolant is emitted from
the bleed hole in top hose.
8.Fit bleed screw to top hose.
9.Continue filling system until coolant level
reaches’MAX’mark on expansion tank.
10.Fit expansion tank filler cap.
11.Position air intake hose and tighten clip screws.
12.Start and run engine until normal running
temperature is reached.
13.If fitted, DO NOT operate air conditioning.
14.Switch off engine and allow to cool.
15.Check for leaks and top-up coolant to’MAX’
mark on expansion tank.
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COOLING SYSTEM
1
REPAIR COUPLING - COOLING FAN
Service repair no - 26.25.19
Remove
1.Remove battery cover.
2.Disconnect battery negative lead.
3.Remove 3 bolts and remove engine acoustic
cover.
4.Remove cooling fan cowl.
NOTE: Thread is RH.
5.Remove cooling fan usingLRT-12-093and
LRT-12-094.
Refit
6.Position cooling fan and tighten using
LRT-12-093andLRT-12-094.
7.Fit cooling fan cowl.
8.Fit engine acoustic cover.
9.Reconnect battery negative lead.
10.Fit battery cover.THERMOSTAT
Service repair no - 26.45.09
Remove
1.Drain cooling system.See Adjustment.
2.Remove cooling fan.See this Section.
3.Release 3 clips and disconnect coolant hoses
from thermostat.
4.Remove thermostat.
Refit
5.Position thermostat, connect hoses and secure
with clips.
6.Fit cooling fan.See this Section.
7.Fill cooling system.See Adjustment.
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26COOLING SYSTEM
2
REPAIR PUMP - COOLANT
Service repair no - 26.50.01
Remove
1.Drain cooling system.See Adjustment.
2.Remove centrifuge.See ENGINE , Repair.
3.Release clip and hose from coolant pump cover.
4.Remove 5 bolts securing coolant pump cover.
5.Remove cover and coolant pump from housing
and discard’O’rings.Refit
6.Clean coolant pump housing and mating faces.
7.Fit new’O’rings to coolant pump and cover.
8.Fit coolant pump and cover and tighten bolts to9
Nm (7 lbf.ft).
9.Connect hose to pump cover and secure clip.
10.Refit centrifuge.See ENGINE , Repair.
11.Refill cooling system.See Adjustment.
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AIR CONDITIONING
1
REPAIR COMPRESSOR
Service repair no - 82.10.20
Remove
1.Remove engine acoustic cover.See ENGINE ,
Repair.
2.Depressurise A/C system.See Adjustment.
3.Remove auxiliary drive belt.See
ELECTRICAL, Repair.
4.Drain cooling system.See COOLING
SYSTEM, Adjustment.
5.Disconnect multiplug from compressor.
6.Remove 2 bolts securing air conditioning pipes
to compressor and discard’O’rings.
CAUTION: Immediately cap all air
conditioning pipes to prevent ingress of
dirt and moisture into the system.
7.Release clips and disconnect top hose from
coolant elbow and heater pipe.
8.Remove 4 bolts securing compressor to
mounting bracket.
9.Remove compressor.Refit
10.Position compressor to mounting bracket and
tighten bolts to25 Nm (18 lbf.ft).
11.Remove caps from compressor and pipe
connections.
12.Clean compressor and pipe connections.
13.Lubricate new’O’rings with refrigerant oil and fit
to compressor.
14.Position A/C pipes to compressor and tighten
bolts to9 Nm (7 lbf.ft).
15.Connect multiplug to compressor.
16.Position top hose and secure with clips.
17.Refill cooling system.See COOLING SYSTEM,
Adjustment.
18.Fit auxiliary drive belt.See ELECTRICAL,
Repair.
19.Recharge A/C system.See Adjustment.
20.Fit engine acoustic cover.See ENGINE ,
Repair.
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