1995 LAND ROVER DISCOVERY compression ratio

SFI
5
DESCRIPTION AND OPERATION REV: 09/95 Engine fuel temperature sensor (EFT Sensor)
This is another resistive sensor. Located on the fuel
rail it measures temperature of the rail rather than the
fuel. The resistance varies with changes in
temperature. The signal is used to increase the
injection pulse time when undergoing hot restarts.
When the fuel is hot, vapourisation occurs in the rail
and bubbles can occur in the injectors. Increasing the
pulse time flushes the bubbles away, and cools the
fuel rail with fuel from the tank. The fault may not be
evident to the driver, there may be a hot restart
problem. The fault is indicated by illumination of the
malfunction indicator light (MIL) on North American
specification vehicles.
Knock sensors
The knock sensor produces an output voltage in
proportion to mechanical vibration caused by the
engine. A sensor is located in each cylinder bank
between 2/4 and 3/5 cylinders. The ECM calculates if
the engine is knocking due to camshaft and
crankshaft sensor signals regarding the position of the
engine in the cycle. The ECM can also work out
exactly which cylinder is knocking and retards the
ignition on that particular cylinder until the knock
disappears. It then advances the ignition to find the
optimum ignition timing for that cylinder. The ECM can
adjust the timing of each cylinder for knock
simultaneously. It is possible that all eight cylinders
could have different advance angles at the same time.
If the camshaft sensor fails, the knock sensor will
continue to work, but as the engine may be running
one revolution out of sychronisation the ECM may
retard the wrong cylinder of the pair e.g. 1 instead of
6. If the knock sensor fails engine knock will not be
detected and corrected. The fault is indicated by
illumination of the malfunction indicator light (MIL) on
North American specification vehicles.Ignition coils
The electronic ignition system uses four double ended
coils. They are mounted on a bracket fitted to the rear
of the engine. The circuit to each coil is completed by
switching within the ECM, allowing each coil to charge
up and fire. Sparks are produced in two cylinders
simultaneously, one on compression stroke, the other
on exhaust stroke. Note that coil 1 feeds cylinders 1
and 6, coil 2 feeds cylinders 5 and 8, coil 3 feeds
cylinders 4 and 7, and coil 4 feeds cylinders 2 and 3.
Due to the ease of combustion in the cylinder on the
compression stroke, more energy is dissipated in that
cylinder. Coil failure will result in a lack of sparks and
misfire in the affected cylinders. The fault is indicated
by illumination of the malfunction indicator light (MIL)
on North American specification vehicles.
Injectors
A multiport fuel injection system (MFI) is used, one
injector per cylinder. Each injector consists of a small
solenoid which is activated by the ECM to allow a
metered amount of fuel to pass into the combustion
chamber. Due to the pressure in the fuel rail and the
shape of the injector orifice, the fuel squirts into the
cylinder in a fine spray to aid combustion. In the
unlikely event of injector failure a misfire will occur as
there will be no fuel to the affected cylinder. The fault
is indicated by illumination of the malfunction indicator
light (MIL) on North American specification vehicles.

STEERING
1
DESCRIPTION AND OPERATION DESCRIPTION
The power assisted steering system incorporates a
compression joint in the lower shaft, designed to
collapse on impact and for certain countries, an air
bag located in the centre of the steering wheel.
The mis-alignment of the upper steering column with
the steering box and the inclusion of two universal
joints and a compression joint in the lower shaft, is
also designed to prevent frontal impact moving the
column toward the driver.
The steering box is located behind the first cross
member of the chassis and is connected to the road
wheels by the drag link and track rod. An hydraulic
damper absorbs shocks in the steering, caused by
road wheel deflections when operating on rough
terrain.Power steering system
The power steering system comprises a hydraulic
pump which is belt driven from the engine and
supplied with fluid from a reservoir that also acts as a
cooler.
The steering box houses a self neutralizing rotary
valve which is part of the worm/valve assy and a
hydraulic piston/rack to assist the mechanical
operation.
The rotary valve which is operated by movement of
the steering wheel, directs fluid pressure to the
appropriate side of the hydraulic piston/rack to provide
assistance.
Power steering system
1. Hydraulic pump
2. Fluid reservoir
3. Steering box
4. Upper column
5. Universal joints
6. Lower shaft
7. Compression joint
8. Drag link

STEERING
3
DESCRIPTION AND OPERATION Steering column components
1. Upper shroud
2. Column harness
3. Cruise control switch (if fitted)
4. Steering wheel and nut
5. Rotary coupler
6. Column switch
7. Shear bolts
8. Switch saddle
9. Upper steering column
10. Universal joint
11. Universal joint bolt
12. Steering column lock assembly13. Lower shroud
14. Column lock/ignition
15. Air bag mounting bracket (if fitted)
16. Air bag module
17. Steering pad (non-airbag)
18. Lower shaft
19. Rubber coupling
20. Compression joint
21. Universal joint
22. Universal joint bolt

STEERING
3
FAULT DIAGNOSIS STEERING DAMPER
The power steering system, as well as reducing the
effort required to manoeuvre the vehicle when
parking, also helps to dampen any deflections of the
road wheels, being transmitted back to the steering
wheel.
When operating the vehicle off road, the road wheels
are often deflected by ruts and boulders causing the
steering wheel to turn left and right. This phenomenon
is known as 'steering kickback'. To subdue the effects
of 'steering kickback', a hydraulic damper is fitted in
the steering linkage between the track rod and the
differential casing. The damper, which offers the same
resistance in extension and compression, is sealed for
life.
Steering damper check
Check the condition operation of the hydraulic
steering damper as follows:
Check procedure
1.Inspect damper for casing damage or leaks.
2.Clamp one end of the damper horizontally in a
vice using soft jaws. Compress and extend the
unit by hand. Resistance should be equal in both
directions.
3.If it is felt that the unit is outside acceptable
limits, fit a new steering damperSTEERING FAULTS
Symptom:-
Excessive kickback through steering wheel - when
driven on rough terrain.
1.Is the steering damper in good working order?
See Steering Damper
NO - Renew unit.See Repair, Steering
Damper
YES - Continue.
2.Is there any looseness or free play in the
steering ball joints and linkage?
YES -
See Steering Linkage Inspect
NO - Continue.
3.Is there any looseness or worn bushes in front
suspension?
YES -
See FRONT SUSPENSION, Repair,
Radius Arm
NOTE: When replacing suspension bushes
ALL bushes and fixings must be replaced.
NO - Continue.
4.Is the steering exceptionally light/sensitive when
driven on good road surface?
YES - See fault symptom -Steering
excessively light/sensitive and
freeplay at steering wheel.
NO - Suspect axle swivel resistance.
5.Check the resistance of the axle swivels.
See
FRONT AXLE AND FINAL DRIVE, Overhaul,
Front Stub Axle, Constant Velocity Joint and
Swivel Pin Housing Non ABS See FRONT
AXLE AND FINAL DRIVE, Overhaul, Front
Stub Axle, Constant Velocity Joint and
Swivel Pin Housing ABS

ENGINE
DESCRIPTION AND OPERATION3
CYLINDER BLOCK, PISTONS AND CAMSHAFT
1.Top compression ring
2.2nd compression ring
3.Oil control ring
4.Piston
5.Gudgeon pin circlips
6.Gudgeon pin
7.Connecting rod
8.Brake servo vacuum pump gasket
9.Core plug
10.Connecting rod bolt
11.Big-end bearing shell
12.Push rod
13.Cam follower slide
14.Roller
15.Cam follower guide
16.Guide retaining bolt
17.Dipstick
18.Dipstick tube
19.Dipstick tube bolt20.Camshaft
21.Oil jet tube
22.Drive pin
23.Camshaft thrust plate
24.Camshaft bearings
25.Main bearing shell
26.Baffle plate
27.Core plugs
28.Oil pressure switch
29.Thermostatic valve assembly
30.Oil filter head
31.Fuel lift pump
32.Fuel lift pump gaskets
33.Spacer - if fitted
34.Brake servo vacuum pump
35.Crankcase breather pipe
36.Oil filter head gasket
37.Baffle plate gasket
38.Oil filter element

ENGINE
DESCRIPTION AND OPERATION15
OPERATION
The 300 TDi is a 4 cylinder, water cooled,
turbocharged diesel engine with a capacity of 2.5
litres.
The cast iron cylinder block is integral with the
crankcase and incorporates direct bored cylinders.
The crankshaft is carried in 5 main bearings,
end-float being controlled by thrust washers which
are positioned on both sides of the centre main
bearing.
The flywheel/drive plate housing is an aluminium
alloy casting secured to the rear of the cylinder
block, it also forms the mounting for the starter
motor. A plugged aperture in the housing allows
access for the insertion of the timing pin.
The aluminium alloy cylinder head carries a
conventional rocker shaft and rockers, operating 2
valves per cylinder via camshaft followers and push
rods from a single camshaft, supported in the
cylinder block by 4 bearings and driven by a gear
and toothed belt from the crankshaft. A lobe formed
between the 2 inner bearing journals provides drive
for the fuel lift pump and another lobe, between the 2
drive end journals provides drive for the brake servo
pump. Camshaft end-float is controlled by a thrust
plate bolted to the cylinder block.
Graphite coated, aluminium alloy pistons are fitted
with 2 compression and an oil control ring and are
secured to the connecting rods by semi-floating
gudgeon pins which are an interference fit in the
small end bush. A swirl chamber is incorporated in
the piston crown to facilitate combustion.
The timing case consists of cast aluminium alloy
front and rear covers which house the oil pump,
crankshaft and camshaft front oil seals and which
also carry the fuel injection pump and drive belt idler
pulley. Housed within the timing case housing is the
crankshaft gear which provides drive for the
camshaft and fuel injection pump gears via a rubber
toothed belt.