engine LAND ROVER DEFENDER 1996 Repair Manual

12ENGINE
4
SPECIFICATIONS, TORQUEMETRIC Nm
M5 6......................................................................................................
M6 9......................................................................................................
M8 25.....................................................................................................
M10 45...................................................................................................
M12 90...................................................................................................
M14 105..................................................................................................
M16 180..................................................................................................
UNC / UNF
1/4 9......................................................................................................
5/16 24...................................................................................................
3/8 39.....................................................................................................
7/16 78...................................................................................................
1/2 90.....................................................................................................
5/8 136....................................................................................................
NOTE: Torque values above are to be used as a guide where no torque is specified.

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
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.

19FUEL SYSTEM
10
DESCRIPTION AND OPERATION Under varying engine speed and load condition the
control unit sends a signal to open the vacuum
modulator which allows a vacuum to be applied above
the EGR diaphragm. The vacuum supply is taken from
a 'T' connector in the brake servo hose. This process
is controlled by an engine speed/load map stored in
the EGR control unit memory.
Engine speed is measured by monitoring the
waveform present on one phase of the generator.
Throttle position is measured via a sensor mounted on
the fuel injection pump throttle lever. Closed loop
control is achieved by allowing the control unit (ECU)
to continually monitor EGR valve lift via the sensor
mounted on the valve; this valve lift is compared with
the actual valve lift required on the control unit map
and adjusted, if necessary.
With coolant temperature between 20°C and 100°C,
the engine having just returned to idle, EGR will shut
off after 25-30 seconds idling.

FUEL SYSTEM
1
ADJUSTMENT THROTTLE CABLE
Adjust
1.Slacken throttle cable adjustment ferrule.
2.Hold throttle lever in fully closed position.
3.Adjust outer cable, by rotating ferrule, to give
1,57 mm (1/16 in) of deflection in the inner cable.
4.Check that throttle opens fully when the throttle
is depressed.EGR THROTTLE POSITION SENSOR
Check
1.Run engine until normal operating temperature is
reached.
2.Switch off engine and disconnect throttle position
sensor multi-plug.
3.Connect an Ohmmeter across pins 1 and 3 of
multi-plug. Ohmmeter should read between 1K
and 1.05K ohms.
4.Connect Ohmmeter across pins 1 and 2 of
multi-plug. Ohmmeter should read between 850
and 900 ohms.
5.If readings are correct, reconnect multi-plug.
6.If readings are not obtained slacken 2 torx
screws securing sensor.
7.Rotate sensor to obtain correct Ohmmeter
reading, then tighten torx screws.
8.Re-check readings and fit multiplug.
9.If, after adjustment, Ohmmeter readings cannot
be achieved, fit new sensor.
See Repair, EGR
throttle position sensor

19FUEL SYSTEM
2
ADJUSTMENT LOW AND HIGH IDLE SPEED ADJUSTMENT
NOTE: The high idle speed (cold start idle)
is automatically set by the setting of the
low idle speed and cannot be adjusted
individually.
1.Check and adjust throttle cable.
See Throttle
cable
2.Start engine and run it until normal operating
temperature is reached.
3.Using a suitable tachometer, check the engine
idle speed,
See ENGINE TUNING DATA,
Information, 300Tdi
4.If adjustment is necessary, first slacken the
locknut on injection pump.
5.Turn adjustment screw clockwise to increase
engine speed or anti-clockwise to decrease the
speed. Run engine at an increased speed for a
few seconds then check idle speed again.
6.When correct speed has been achieved, hold
adjuster screw steady while tightening locknut.
NOTE: The low idle speed control is the
only permitted adjustment in service. Any
additional adjustments required must be
entrusted to authorised Bosch agents.THROTTLE PEDAL ADJUSTMENT
Adjust
1.First ensure that throttle cable is correctly
adjusted
See Throttle cable
2.Depress throttle pedal, by hand, to full extent of
injection pump lever travel. Slacken locknut and
adjust throttle pedal stop screw to take up
clearance between screw and bulkhead. Ensure
no strain is placed upon throttle cable and pump
lever.
3.Retighten locknut.

FUEL SYSTEM
3
ADJUSTMENT INJECTION PUMP TIMING - CHECK AND ADJUST
Service repair no - 19.30.01
1.Viewing the valve mechanism through oil filler
aperture, turn crankshaft clockwise until inlet
valve of No.1 cylinder has just closed. No.1
cylinder is now just before TDC.
2.Remove blanking plug from flywheel housing
and insert timing toolLRT-12-044, locating
centre pin on flywheel.
NOTE: A chassis undertray may be fitted
on some vehicle derivatives to conform to
legal requirements. When under chassis
adjustments or remove and refit procedures are
required, it may be necessary to remove the
undertray and/or integral access panels.
See
CHASSIS AND BODY, Repair, Front undertray
or
See CHASSIS AND BODY, Repair, Rear undertray
3.Cearfully rotate crankshaft clockwise until centre
pin engages timing slot in flywheel.
4.Remove injection pump access plate, complete
with gasket, from front cover plate.
5.Fit locking pinLRT-12-045/2to injection pump
gear. If difficulty is experienced in inserting pin,
adjustments will be needed to correctly set
injection pump timing as follows:
6.Support injection pump retaining nut to prevent
strain on timing belt.
7.Slacken the 3 keeper plate retaining bolts.
8.Carefully turn fixing nut and keeper plate until
locking pin can be inserted, without restriction,
into injection pump gear.
9.Tighten keeper plate bolts to
25 Nm (18 lbf/ft)
and remove locking pin.
10.Refit injection pump access plate plate and
gasket.
11.Remove flywheel timing tool and refit blanking
plug.
12.Run engine until normal operating temperature is
reached and check that idle speed adjustment,
See low and high idle speed adjustmentand
throttle cable adjustment
See Throttle cable
are correct.

19FUEL SYSTEM
4
ADJUSTMENT TURBOCHARGER BOOST PRESSURE - CHECK
Service repair no - 19.42.06
1.Disconnect actuator hose from turbocharger and
insert a suitable 'T' piece connector.
2.Connect a short length of suitable hose to
turbocharger and 'T'piece.
3.Connect further hose to 'T' piece and pressure
gaugeLRT-12-011. The pressure gauge hose
must be long enough to reach into the vehicle
cab so that the gauge can be observed by driver
or passenger.
4.To check maximum boost pressure, drive
vehicle normally, but in such a manner that full
throttle can be maintained whilst climbing a hill
with engine speed held steady between 2,500
and 3,000 rev/min. Under these circumstances
boost pressure should read 0,95 - 1,09 Kgf/cm
2
(13.5 - 15.5 lb/in2).PRIMING THE FUEL SYSTEM
Service repair no - 19.50.01
NOTE: If the fuel system has been
completely drained carry out the
procedures for priming both the
sedimentor, if fitted, and fuel filter and injection
pump.
Sedimentor and fuel filter
If the sedimentor or fuel filter have been dismantled
and air has entered the fuel system carry out the
following procedure:
1.Slacken fuel filter bleed screw.
2.Operate hand priming lever on fuel lift pump until
fuel, free from air, emerges from filter.
NOTE: Ensure that the fuel pump lever is
on the bottom of operating cam when
priming, otherwise maximum movement of
the lever cannot be achieved.
3.Tighten filter bleed screw whilst fuel is still
emerging.

FUEL SYSTEM
5
ADJUSTMENT Fuel injection pump
If the fuel injection pump has been removed or
renewed carry out the following:
1.Slacken fuel inlet pipe banjo bolt at injection
pump.
2.Operate hand priming lever on fuel lift pump until
fuel, free from air, emerges from injection pump.
3.Tighten banjo bolt whilst fuel is still emerging.
4.Crank engine until fuel is drawn through the
system and engine starts.
5.Check fuel connections for leaks.

FUEL SYSTEM
3
REPAIR FUEL INJECTORS
Service repair no - 19.60.10
Remove
NOTE: When a fuel injector is considered
to be the cause of irregular running and
loss of power it will be necessary to fit a
donor set of injectors to determine which injector
is at fault. DO NOT attempt to dismantle or carry
out spray tests on the fuel injectors. This work
can only carried out by authorised Bosch dealers.
1.Remove oil filler cap and release sound
insulation cover from top of engine.
2.Disconnect high pressure fuel supply pipes from
injectors and injection pump. Remove in pairs.
3.Disconnect spill return hose(s) from injectors.
4.Plug pipes and injector connections to prevent
the ingress of dirt and foriegn matter.5.Remove retaining nut and release each injector
clamp plate from cylinder head.
6.Remove injector and discard copper washer.
Refit
7.Ensure injectors and seating in cylinder head are
clean.
8.Lightly grease a new copper sealing washer and
position on each injector.
9.Fit injectors in cylinder head with spill return
outlets facing outward.
10.Secure injector with clamp plate and nut. Tighten
nut to
25 Nm (18 lbf/ft).
NOTE: The clamp plates are slightly
curved and should be fitted with the
convex side uppermost.
11.Fit the spill return pipe with a single copper
washer under the head of the banjo bolt and 2
copper washers fitted between the injector and
the banjo. Tighten banjo bolt to
10 Nm (7 lbf/ft).
12.Fit high pressure pipes to injectors and injection
pump. Tighten union nuts to
28 Nm (21 lbf/ft).
13.Fit sound insulation cover and oil filler cap.