heater LAND ROVER DEFENDER 1996 User Guide

12ENGINE
2
SPECIFICATIONS, TORQUE REV: 05/99Nm
Cylinder head
Cylinder head to cylinder block
M10 x 117 40 Nm + 60° ..........................................................................................
M12 x 100 40 Nm + 60° ..........................................................................................
M12 x 140 40 Nm + 60°+20° ......................................................................................
Stub pipe heater feed 22.................................................................................
Water temperature sensor 14.........................................................................
Blanking plug cylinder head 14.......................................................................
Engine lifting brackets 25................................................................................
Electrical harness clip bracket 25...................................................................
Exhaust manifold stud 10................................................................................
Exhaust manifold nut 45.................................................................................
Inlet manifold stud 8.......................................................................................
Inlet manifold nut and bolt 25..........................................................................
Air temperature sensor, inlet manifold 14.......................................................
Blanking plug, inlet manifold 14......................................................................
Heatshield to inlet manifold 6.........................................................................
Glow plug 20...................................................................................................
Glow plug terminal nut 2................................................................................
Injector clamp (stud) 8...................................................................................
Injector clamp (nut) 25....................................................................................
Thermostat housing 25...................................................................................
Water outlet elbow to thermostat housing 25..................................................
Water temperature switch, thermostat housing 11..........................................
Plug thermostat housing 6.............................................................................
Rocker shaft pedestal bolt 5 Nm + 50° ..................................................................
Rocker cover (stud) 8.....................................................................................
Rocker cover (fixing nut) 10............................................................................
Breather cyclone to rocker cover 9................................................................
Tappet adjusting nut 16..................................................................................
Front cover to cylinder block 25......................................................................
Front cover plate to front cover 25..................................................................
Static idler - timing belt (stud) 10.....................................................................
Static idler - timing belt (nut) 45......................................................................
Tensioner (timing belt) 45...............................................................................
Camshaft hub bolt 80......................................................................................
Timing pulley to camshaft hub 25...................................................................
Fuel injection pump (stud) 8...........................................................................
Fuel injection pump (nut) 25...........................................................................
Abutment bracket to injection pump 25...........................................................
Support bracket injection pump to cylinder block 25.......................................
Fuel injection pump access plate to front cover plate 25................................
Timing pulley to injection pump hub 25...........................................................
TV Damper pulley bolt to crankshaft 80 Nm + 90° ..................................................
Fan pulley to hub 25.......................................................................................
Fan and viscous coupling to hub 45...............................................................
Auto tensioner, auxiliary drive (stud) 14..........................................................
Auto tensioner, auxiliary drive (nut) 45...........................................................
Auxiliary mounting bracket to cylinder block (stud) 8.....................................
Auxiliary mounting bracket to cylinder block (bolt and nut) 25........................
Water pump to block and mounting plate 25..................................................
Water pump pulley to hub 25..........................................................................

19FUEL SYSTEM
2
DESCRIPTION AND OPERATION A mechanical lift pump, with a hand priming facility, is
driven by the camshaft, and is mounted on the RH
side of the engine.
A fuel filter, with a replaceable element and
incorporating a water separator, is mounted on the
front RH side of the engine compartment.
A fuel sedimentor may be fitted when the vehicle is
operating in more arduous conditions, and is used to
minimise water deposits in the fuel system before
reaching the fuel pump and filter.
Fuel injection is carried out by a Bosch direct injection
pump, incorporating a cold start advance unit and a
high idle setting. The pump is mounted on the RH side
of the engine and is driven directly by gears in the
front cover from the crankshaft. The pump meters and
distributes fuel to 4 pintle type injectors located in
pre-combustion chambers in the cylinder head. Four
heater plugs, located in the cylinder head directly
below each injector, are fitted to improve cold starting.
An optional hand throttle, for use with a centre power
take off, is located on the fascia to the LH side of the
fuse box, and is linked independently to the fuel
injection pump throttle lever.
Air intake
The air cleaner is mounted on the RH side of the
engine and is connected by hoses to the cold air
intake duct and turbocharger inlet. Fitted between the
air cleaner and turbocharger is the crankcase breather
hose which connects to a breather filter on the rocker
cover.
A single stage turbocharger, fitted between the
exhaust manifold and exhaust down pipe, is
connected by hoses to the air cleaner and an
intercooler which is mounted on the LH side of the
radiator. The intercooler is connected by a hose to the
inlet manifold. When an EGR valve is fitted to the
turbocharger, additional pipes/hoses are used to
connect the components.Exhaust gas recirculation (EGR), when fitted.
Exhaust gas recirculation is controlled by an ECU
mounted under the front centre seat or cubby box and
receives the following inputs:
·Engine temperature from coolant temperature
sender unit on LH side of cylinder head.
·Throttle position from potentiometer on injection
pump.
·Engine speed from speedometer.
When all correct signals are received, the EGR
solenoid allows vacuum to open EGR valve and
recirculate a portion of the exhaust gas. See J6196 for
the EGR system component location and 'Operation'
for full system function.

FUEL SYSTEM
7
DESCRIPTION AND OPERATION
FUEL SYSTEM COMPONENT LOCATION
1.Fuel filter bleed screw
2.Fuel filter
3.Turbocharger
4.Actuator
5.Air cleaner
6.Fuel injector7.Heater plug
8.Heater plug controller
9.Coolant temperature transmitter
10.Fuel injection pump
11.Fuel lift pump
12.Intercooler

FUEL SYSTEM
9
DESCRIPTION AND OPERATION OPERATION
Diesel engines operate by compression ignition. The
rapid compression of air in the cylinder during the
compression cycle heats the air and when fuel is
injected into the heated air, it ignites instantaneously.
During cold tarting, automatically controlled heater
plugs assist in raising the temperature of the
compressed air to ignition point.
A cold start advance unit advances the injection timing
to further assist starting. Idle quality is improved by
the high idle setting.
The engine is supplied with pre-compressed air by a
single stage turbocharger.
Exhaust gases passing over a turbine cause it to
rotate, driving a compressor mounted on the turbine
shaft. Air drawn from the cold air intake passes, via
the air cleaner, to the turbocharger where it is
compressed. Compression in the turbocharger warms
up the air considerably, so that it expands. As a result
the air mass per cylinder is reduced, having a
negative effect on power output. By fitting a charge-air
intercooler, located on the LH side of the radiator, the
air is cooled before reaching the cylinders. This
increases power output through increased mass of
oxygen in the combustion process, as well as
maximising engine durability, through maintaining
lower piston and head temperatures.
Fuel is drawn from the tank by a mechanical lift pump
and passes to the injection pump via a filter. In
addition to removing particle contamination from the
fuel, the filter incorporates a water separator, which
removes and stores water.
The sedimentor/s, when fitted, is located adjacent to
the fuel tank/s and separates contamination and water
particles in the fuel before reaching the fuel lift pump.
The injection pump meters a precisely timed, exact
quantity of fuel to the injectors in response to throttle
variations, injection timing varying with engine speed.
Any excess fuel delivered to the injection pump is
passed back to the tank via the spill return line.
Fuel is injected in a finely atomised form into the main
combustion chamber, the burning fuel expands
rapidly, creating extreme turbulence which mixes the
burning fuel thoroughly with the compressed air,
providing complete combustion.Cold Starting is assisted by heater plugs, a cold start
advance unit and a high idle setting.
Heater plugs
Heater plug operation is controlled by a timer unit,
start relay and resistor. When the ignition is turned on
the timer unit is energised, the heater plugs start to
operate and a warning light on the dashboard
illuminates, remaining on until the heater plugs are
automatically switched off.
The length of time the heater plugs will operate is
dependent on under bonnet temperature, which is
monitored by a sensor located in the timer unit.
Starting the engine results in the power supply to the
heater plugs passing through the resistor, which
reduces their operating temperature. The heater plugs
are cut out either by the temperature sensor in the
timer, or by a microswitch on the injection pump which
operates when the throttle is depressed.
Cold start advance
The cold start advance unit is connected to the engine
cooling system via hoses. It contains a temperature
sensitive element which is retracted when cold and
pulls the advance lever, via cable, towards the rear of
the pump against spring pressure. As coolant
temperature rises, the cold start element expands
releasing tension on the cable and allowing spring
pressure to move the advance lever forwards.
Exhaust gas recirculation (EGR), when fitted
Operation of the EGR system is dependent on the
following:
·Engine temperature - must be between 20°C and
100°C approx.
·Engine speed - must be between 630 and 2850
rev/min.
·Engine load - calculated by throttle position
sensor.
·EGR valve lift position.
·Duration of engine idling.

FUEL SYSTEM
11
REPAIR HEATER PLUGS
Service repair no - 19.60.31
Remove
1.Disconnect battery.
No.1 heater plug - air conditioning models:
2.Release drive belt from compressor pulley.See
AIR CONDITIONING, Repair, Compressor
drive belt
3.Remove 4 bolts securing compressor to front
cover, move compressor aside.
No.3 heater plug:
4.Remove retaining bolt and withdraw breather
valve from rocker cover. Remove and discard 'O'
ring.
All heater plugs:
5.Remove terminal nut and disconnect wire from
heater plug terminal.
6.Unscrew heater plug.
Refit
7.Clean heater plug and seating.
8.Coat threads of heater plug with suitable
anti-seize compound operational to a
temperature of 1000°C.
9.Fit heater plug, tighten to
23 Nm (17 lbf/ft).
10.Connect wire to heater plug terminal and secure
with nut.
NOTE: Feed wire must be connected to
No. 4 heater plug terminal.
No. 3 heater plug:
11.Lubricate new 'O' ring with engine oil and fit to
breather valve.
12.Fit valve to rocker cover, tighten to bolt to
15 Nm
(11 lbf/ft).
No. 1 heater plug - air conditioning models
13.Position compressor to front cover, fit bolts and
tighten to
25 Nm (18 lbf/ft).
14.Fit drive belt to compressor pulley and adjust
tension.
See AIR CONDITIONING, Repair,
Compressor drive belt
All models:
15.Reconnect battery.

19FUEL SYSTEM
12
REPAIR HEATER PLUG CONTROL UNIT
Service repair no - 19.60.33
Remove
1.Disconnect battery.
2.Remove screw securing control unit to bulkhead.
3.Disconnect multi-plug and release control unit.
Refit
4.Fit harness multi-plug to control unit.
5.Secure control unit to bulkhead.
6.Reconnect battery.AIR CLEANER
Service repair no - 19.10.01
Remove
1.Slacken hose clip and detach outlet hose.
2.Release clips and open air cleaner retaining
straps.
3.Lift up air cleaner, slacken hose clip and detach
inlet hose.
4.Remove air cleaner.
Refit
5.Position air cleaner and connect inlet hose.
6.Close air cleaner retaining straps and secure
lock clips.
7.Connect outlet hose.
NOTE: If an EGR fuel system is fitted,
ensure the modulator valve vacuum spill
pipe is secure in the outlet hose.
AIR CLEANER ELEMENT
Service repair no - 19.10.10
For remove and refit procedure.
See SECTION 10,
Maintenance, Under bonnet maintenance

COOLING SYSTEM
1
DESCRIPTION AND OPERATION ENGINE COOLING SYSTEM
Description
The complete cooling system of the 300Tdi engine
incorporates three independent functions:- Engine
(coolant) cooling; Turbo (charge air) intercooling;
Engine oil cooling.The intercooler is a separate aluminium unit, located
on the LH side of the engine compartment adjacent to
the radiator, sharing the same upper and lower
mountings. For details of turbo intercooling
See
FUEL SYSTEM, Description and operation,
Operation
. The oil cooler matrix is an integral part of
the radiator. Pre-formed pipes/hoses are used to link
the components within the separate systems as
shown below.
Engine cooling system
1.Radiator
2.Thermostat housing
3.Radiator bottom hose
4.Viscous fan
5.Water pump
6.Radiator top hose
7.Heater return hose
8.Coolant supply hose
9.By-pass hose
10.Radiator bleed (purge) hose
11.Bleed (purge) hose, thermostat housing
12.'Y' piece ejector
13.Expansion tank14.Heater rail
15.Heater unit
16.Heater feed hose
17.Intercooler
18.Air cleaner
19.Air feed hose
20.Turbocharger
21.Charge air supply pipe/hose
22.Cooled charge air supply hose
23.Exhaust manifold
24.Engine oil cooler
25.Feed pipe, engine oil cooler
26.Return pipe, engine oil cooler
27.Oil filter

26COOLING SYSTEM
2
DESCRIPTION AND OPERATION ENGINE (COOLANT) COOLING
Description
The 300Tdi engine uses a pressurised cooling system
and cross flow radiator which is supplied with coolant
from an expansion tank mounted on the RH side of
the engine compartment. A belt driven centrifugal
water pump, fitted to an auxiliary mounting assembly,pumps coolant to the engine crankcase, cylinder head
and vehicle heater unit.
An eleven bladed fan, incorporating a viscous
coupling, is driven by an independent pulley secured
to the front cover plate. The thermostat housing,
bolted to the front of the cylinder head, is fitted with a
vent valve that purges excessive air pressure and
coolant back to the expansion tank.
Engine coolant circulation (engine warm - thermostat open).
1.Radiator
2.Thermostat/housing
3.Radiator bottom hose
4.Viscous fan
5.Water pump
6.Radiator top hose
7.Heater return hose
8.Coolant supply hose9.By-pass hose
10.Radiator bleed (purge) hose
11.Thermostat housing bleed (purge) hose
12.'Y' piece ejector
13.Expansion tank
14.Heater rail
15.Heater unit
16.Heater feed hose

COOLING SYSTEM
3
DESCRIPTION AND OPERATION COOLANT CIRCULATION
Operation
When the engine is started from cold the thermostat
(2) prevents coolant circulation through the radiator by
closing off the top hose (6). During the engine warm
up period the water pump (5) circulates coolant to the
cylinders in the crankcase and through separate ports
to the cylinder head. At the rear of the cylinder head a
proportion of the flow is diverted through a heater feed
pipe (16) to the matrix of the heater unit (15). The
coolant is then carried, via a heater return rail (14) and
hoses (7), back to the water pump. The remaining
coolant flows through a by-pass hose (9) at the
thermostat housing and back to the water pump to
complete the first cycle.
When the normal engine running temperature is
reached, the thermostat opens, closing off the by-pass
hose (9). Coolant is then circulated via the top hose
(6) and through the radiator, where it is cooled and
drawn from the radiator bottom hose (3) by the water
pump (5). The coolant circulation through the
crankcase and cylinder head remains the same.
Two bleed pipes (10) and (11) help control the system
pressure by purging excess air and coolant to the
expansion tank via the 'Y'piece ejector (12).VISCOUS 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 by means of 'silicone fluid'.
1.Input (drive) member
2.Output (driven) member
3.Sensing mechanism (bi-metal coil)
The fan drive has to be engaged only periodically,
between 5% and 10%, during normal operating
conditions, because the engine is cooled by ram air
for most of the time.

COOLING SYSTEM
3
REPAIR WATER PUMP
Service repair no - 26.50.01
Remove
1.Disconnect battery.
2.Drain cooling system.
See Adjustment, Drain
and refill cooling system
3.Remove radiator top hose.
4.Remove intercooler top hose.
5.Slacken water pump and power steering pump
pulley retaining bolts.
6.Remove drive belt.
See ELECTRICAL, Repair,
Auxiliary drive belt
7.Unscrew flange nut and remove belt tensioner.
8.Remove oil filler cap and remove rocker cover
insulation.
9.Slacken retaining clip and disconnect hose at
heater rail.
10.Unscrew 3 bolts and remove water pump pulley.
11.Unscrew 3 bolts and remove power steering
pump pulley.
12.Remove 8 bolts securing water pump, noting
location of 3 through bolts into cylinder block.
13.Withdraw pump and gasket from auxiliary
mounting bracket.
14.Clean all gasket material from mating faces.
Refit
15.Using new gasket, fit water pump to mounting
bracket. Tighten bolts to
25 Nm (18 lbf/ft).
16.Fit power steering pump pulley.
17.Fit water pump pulley. Tighten bolts of both
pulleys to
25 Nm (18 lbf/ft).
18.Fit drive belt.See ELECTRICAL, Repair,
Auxiliary drive belt
19.Fit hose at heater rail.
20.Fit rocker cover insulation and oil filler cap.
21.Fit drive belt tensioner. Tighten retaining nut to
45 Nm (33 lbf/ft).
22.Fit intercooler top hose.
23.Fit radiator top hose.
24.Refill cooling system.
See Adjustment, Drain
and refill cooling system
25.Reconnect battery.