oil temperature LAND ROVER DEFENDER 1999 User Guide

COOLING SYSTEM
5
DESCRIPTION AND OPERATION A - EU 3 Models
B- Pre EU3 Models
GENERAL
The cooling system used on the Diesel engine is a pressure relief by-pass type system which allows coolant to
circulate around the engine block and heater circuit when the thermostat is closed. With coolant not passing
through the by-pass or the radiator promotes faster heater warm-up which in turn improves passenger comfort.
A coolant pump is mounted on a casting behind the PAS pump and is driven from the PAS pump at crankshaft
speed by the auxiliary drive belt. The pump mounting casting connects with passages in the cylinder block and
pumps coolant from the radiator through the cylinder block.
A viscous fan is attached to an idler pulley at the front of the engine. The fan is attached to a threaded spigot on
the pulley with a right hand threaded nut. 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 pipe. The housing contains a wax element thermostat 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 radiator, cooled by the ambient
air, conducts through 10% of the thermostat sensitive area.
In cold ambient temperatures, the engine temperature is raised approximately 10°C (50°F) to compensate for the
heat loss of 10% exposure to the cold coolant returning from the radiator bottom hose.
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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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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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26COOLING SYSTEM
10
DESCRIPTION AND OPERATION 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 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.
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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
13
DESCRIPTION AND OPERATION 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 the 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 causes 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 the 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.
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82AIR CONDITIONING
2
ADJUSTMENT Recharging
WARNING: Refrigerant must always be
recycled before re-use, to ensure that the
purity of the refrigerant is high enough for
safe use within the air conditioning system.
Recycling should always be carried out with
equipment which is design certified by
Underwriter Laboratory Inc. for compliance with
SAE-J1991. Other equipment may not re-cycle the
refrigerant to the required level of purity.
WARNING: A R134a Refrigerant Recovery
Recycling Recharging station must not be
used with any other type of refrigerant.
WARNING: R134a refrigerant from
domestic and commercial sources must
not be used in motor vehicle air
conditioning systems.
CAUTION: When a major repair has been
carried out, a leak test should be carried
out using inert gas.
1.Close valves on refrigerant station.
2.Close valve on oil charger.
3.Disconnect yellow hose from refrigerant station.
4.Remove lid from oil charger.
5.Pour correct quantity of refrigerant oil into oil
charger.
6.Fit lid to oil charger.
7.Connect yellow hose to refrigerant station.
8.Open valve on oil charger.
9.Move pointer on refrigerant gauge to mark
position of refrigerant drop.
10.Slowly open correct valve on refrigerant station
and allow vacuum to pull refrigerant into system.
11.Close valve on refrigerant station when correct
amount of refrigerant has been drawn into air
conditioning system.
12.If the full charge is not accepted by the system,
start the engine and run it at 1,500 rev/min for a
minimum of 2 minutes. Switch on the air
conditioning system, open the vehicle windows,
set the temperature control to cold and the
blower switch to maximum.
13.Consult Refrigerant station instruction manual for
correct procedure to complete the charge.
14.Turn Main switch to’OFF’.
15.Close valves on connectors.
16.Disconnect high and low pressure hoses from
connectors.
17.Fit dust caps to connectors.
18.Carry out performance test on air conditioning
system.
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AIR CONDITIONING
3
REPAIR Refit
6.Position bracket to receiver drier and tighten
clamp bolt.
7.Position receiver to chassis and tighten bolts.
8.Remove plugs from A/C pipes.
9.Lubricate new’O’rings with refrigerent oil.
10.Fit’O’rings, position pipes and tighten bolts to8
Nm (6 lbf.ft).
11.Recharge A/C system.See Adjustment.RELAY - TEMPERATURE CONTROL - FROM 02MY
Service repair no - 82.20.40
Remove
1.Remove front speaker from drivers side.See
ELECTRICAL, Repair.
2.Release relay from support bracket.
3.Disconnect multiplug and remove relay.
Refit
4.Connect multiplug to relay and fit relay to
bracket.
5.Fit front speaker.See ELECTRICAL, Repair.
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ELECTRICAL
23
DESCRIPTION AND OPERATION Heated front seats are a new feature for 2002MY and are available as part of a cold climate pack on Td5 engine
variants only. The heated seats system comprises, two latching switches, a seat relay and heater elements.
The latching switches are located in the fascia. Each switch individually controls its related seat heater elements.
Each switch contains a tell tale lamp to indicate when the seat heaters are active. There is no timer function for the
seat heater operation and the seat heaters will remain active for as long as the switch is latched in and the ignition
is in position II.
The seat heater relay is located in the passenger compartment fuse box and shares its supply and operation with
the front window lift system. The relay receives a permanent battery voltage supply via fusible links 1 and 3 in the
under seat fuse box and fuse 28 in the satellite fuse box. The relay coil is connected to the ignition switch via fuse
7 in the passenger compartment fuse box and an earth point. When the ignition switch is moved to position II, the
relay coil is energised and the contacts close. Power is supplied from the relay to each of the seat heater
switches.
The heater elements are fitted in the seat cushion and squab on the drivers and passenger front seats and are
wired in series. The wiring looms for the elements is long enough to allow the seat squab to be lifted for access to
the under seat fuse box or the storage bin/battery without straining the wiring. The centre seat, if fitted, does not
have heater elements.
The cushion element receives the feed from the switch and contains a thermostatically controlled switch. When
the element temperature reaches 37±3°C (98±3°F) the thermostat cuts the supply to the cushion and squab
elements for that seat. As the temperature of the element falls to 28±3°C (82±3°F), the thermostat will close the
switch contacts allowing power to flow to both elements causing them to heat up again. In this way the thermostat
maintains the cushion and squab element temperatures between the figures stated.
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ELECTRICAL
25
DESCRIPTION AND OPERATION Electric window lift is a new feature for 02MY. The electric windows are only available on the front driver and
passenger doors. Rear passenger doors retain the manual window lift regulator mechanism.
The window lift system comprises a window motor in each front door, two window lift switches located in the fascia
switch panel and a relay, located adjacent to the passenger compartment fusebox. The windows are only
operative when the ignition switch is in position II.
Each window lift motor is located in the door, behind the trim casing. The motor and regulator form a handed
assembly and are not available separately as serviceable items.
The window lift relay receives a permanent battery feed via fusible links 1 and 3 in the under seat fuse box. The
relay coil has one side connected to earth with the other side receiving a feed from the ignition switch position II.
When the ignition is in position II, the relay is energised and battery voltage is supplied to each of the window lift
switches. On vehicles with heated seats, the relay is shared with the heated seat circuit.
Each switch has two wires to its applicable motor. When the switch is operated in either the up or down position,
one wire is supplied with a feed and the other is connected to earth as applicable for the selection made.
Each motor has thermal cut-out protection. If the window reaches the top or bottom limit of its travel or an object
obstructs the window, the thermal cut-out will sense the increased load on the motor and cut the power supply to
the motor brush contacts.
The cut-out time is between 3.5 to 5.0 seconds, with a time to restart of between 1 to 10 seconds. These figures
are based on an ambient temperature of 20°C (68°F) and a voltage of 13.5V.
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