power steering LAND ROVER DISCOVERY 2002 Workshop Manual

CONTENTS
14 CONTENTS
Steering system component layout................................................................................................. 57-1
Steering column assembly and intermediate shaft ......................................................................... 57-2
Steering box.................................................................................................................................... 57-4
Description ...................................................................................................................................... 57-5
Operation ........................................................................................................................................ 57-15
ADJUSTMENTS
Steering box - check and adjust ..................................................................................................... 57-17
Hydraulic system - bleed ................................................................................................................ 57-18
Steering linkage - centralise ......................................................................................................... 57-18
Wheel alignment - front ................................................................................................................. 57-19
Power steering pressure check - diesel models ............................................................................. 57-20
Power steering pressure check - V8 LHD models .......................................................................... 57-22
Power steering pressure check - V8 RHD models ......................................................................... 57-24
REPAIRS
Power steering box - V8 ................................................................................................................. 57-27
Power steering box - LHD - diesel .................................................................................................. 57-30
Steering box - RHD - diesel ............................................................................................................ 57-34
Seal - input shaft - steering box ..................................................................................................... 57-37
Seal - output shaft - steering box ................................................................................................... 57-38
Pump - power steering - V8 ............................................................................................................ 57-39
Pump - power steering - diesel ....................................................................................................... 57-41
Steering column assembly and lock ............................................................................................... 57-42
Shaft - intermediate and universal joint - steering column ............................................................ 57-44
Nacelle - steering column ............................................................................................................... 57-47
Drop arm - steering box ................................................................................................................ 57-47
Ball joint - track rod ....................................................................................................................... 57-48
Ball joint - drag link ....................................................................................................................... 57-49
Drag link ........................................................................................................................................ 57-50
Damper - steering ......................................................................................................................... 57-51
Steering wheel ............................................................................................................................... 57-51
FRONT SUSPENSION .............................................................................. 60-1
DESCRIPTION AND OPERATION
Front suspension component layout (ACE torsion bar shown)....................................................... 60-1
Front suspension components (ACE torsion bar shown) ............................................................... 60-2
Description ...................................................................................................................................... 60-4
DESCRIPTION AND OPERATION
ACE system component layout....................................................................................................... 60-9
ACE system control diagram .......................................................................................................... 60-10
Description - ACE ........................................................................................................................... 60-11
Operation ........................................................................................................................................ 60-25
ADJUSTMENTS
ACE hydraulic system bleeding ..................................................................................................... 60-27
Fluid level check - ACE system ...................................................................................................... 60-27
REPAIRS
Bushes - Panhard rod ................................................................................................................... 60-29
Ball joint - upper - steering knuckle ............................................................................................... 60-30
Ball joint - lower - steering knuckle ................................................................................................. 60-31
Steering knuckle ........................................................................................................................... 60-32
Road spring - front ........................................................................................................................ 60-34
Wheel hub....................................................................................................................................... 60-35
Damper - front ............................................................................................................................... 60-37

INTRODUCTION
01-4
HRW Heated Rear Window
HSLA High Strength Low Alloy
ht/HT High tension
IACV Idle Air Control Valve
IAT Intake Air Temperature
ICE In-Car Entertainment
i.dia. Internal diameter
IDM Intelligent Driver Module
IF Intermediate Frequency
in
3Cubic inch
ILT Inlet Throttle
IPW Injector Pulse Width
ISO International Organisation for
Standardisation
ITS Inflatable Tubular Structure
k Thousand
kg Kilogramme
kg/h Kilogrammes per hour
km Kilometre
km/h Kilometres per hour
kPa KiloPascal
KS Knock Sensor
lLitre
lb(s) Pounds
lbf Pounds force
lbf.in Pounds force inches
lbf/in
2Pounds per square inch
lbf.ft Pounds force feet
λLambda
lc Low compression
LCD Liquid Crystal Display
LED Light Emitting Diode
LEV Low Emission Vehicle
LH Left-Hand
LHD Left-Hand Drive
LSM Light Switch Module
LVS Liquid Vapour Separator
mMetre
µMicro
MAF Mass Air Flow
MAP Manifold Absolute Pressure
MET Mechanical, Electrical and Trim
MFU Multi-Function Unit
MFL Multi-Function Logic
max. Maximum
MEMS Modular Engine Management
System
MIG Metal/Inert Gas
MIL Malfunction Indicator Lamp
MPa MegaPascal
MOSFET Metal Oxide Semiconductor Field
Effect Transistor
min. Minimum
- Minus (tolerance)
' Minute (angle)
mm Millimetre
mph Miles per hour MPi Multi-Point injection
MV Motorised Valve
MY Model Year
NAS North American Specification
(-) Negative (electrical)
Nm Newton metre
No. Number
NO
2Nitrogen Dioxide
NO
xOxides of Nitrogen
NTC Negative Temperature
Coefficient
NRV Non Return Valve
OBD On Board Diagnostics
OBM On Board Monitoring
o.dia. Outside diameter
OAT Organic Acid Technology
ORM Off-road Mode
ΩOhm
PAS Power Assisted Steering
PCB Printed Circuit Board
PCV Positive Crankcase Ventilation
PDC Parking Distance Control
PDOP Position Dilation Of Precision
PI Programme Information
PPS Pulse Per Second
PS Programme Service
psi Pounds per square inch
pts. Pints
% Percentage
+ Plus (tolerance) or Positive
(electrical)
±Plus or minus (tolerance)
PTC Positive Temperature Coefficient
PTFE Polytetrafluorethylene
PVC Polyvinyl chloride
PWM Pulse Width Modulation
RDS Radio Data Service
rRadius
:Ratio
ref Reference
REG Regionalisation
RES Rover Engineering Standards
rev/min Revolutions per minute
RF Radio Frequency
RGB Red / Green / Blue
RH Right-Hand
RHD Right-Hand Drive
ROM Read Only Memory
RON Research Octane Number
ROV Roll Over Valve
ROW Rest Of World
SAE Society of Automotive Engineers
SAI Secondary Air Injection
" Second (angle)
SLABS Self Levelling and Anti-Lock
Brake System
SLS Self Levelling Suspension
SOHC Single Overhead Camshaft

GENERAL INFORMATION
03-13
Self-locking nuts
Self-locking nuts, i.e. nylon insert or deferred thread
nuts can be re-used providing resistance can be felt
when the locking portion of the nut passes over the
thread of the bolt or stud.
Where self-locking nuts have been removed, it is
advisable to replace them with new ones of the same
type.
Flexible Pipes and Hoses
General
When removing and installing flexible hydraulic pipes
and hoses, ensure that the following practices are
observed to ensure component serviceability.
lBefore removing any brake or power steering
hose, clean end fittings and area surrounding
them as thoroughly as possible.
lObtain appropriate plugs or caps before
detaching hose end fittings, so that the ports can
be immediately covered to prevent the ingress
of dirt.
lClean hose externally and blow through with
airline. Examine carefully for cracks, separation
of plies, security of end fittings and external
damage. Reject any faulty hoses.
lWhen refitting a hose, ensure that no
unnecessary bends are introduced, and that
hose is not twisted before or during tightening of
union nuts.
lFit a cap to seal a hydraulic union and a plug to
its socket after removal to prevent ingress of
dirt.
lAbsolute cleanliness must be observed with
hydraulic components at all times.
lAfter any work on hydraulic systems, carefully
inspect for leaks underneath the vehicle while a
second operator applies maximum brake
pressure to the brakes (engine running) and
operates the steering.

LIFTING AND TOWING
08-2
Reverse procedure when removing vehicle from
stands.
Hydraulic ramps
Use only a 'drive on' type ramp which supports a
vehicle by it's own road wheels. If a 'wheel free'
condition is required, use a 'drive on' ramp
incorporating a 'wheel free' system that supports
under axle casings. Alternatively, place vehicle on a
firm, flat floor and support on axle stands.
TOWING
Towing
The vehicle has permanent four wheel drive. The
following towing instructions must be adhered
to:
Towing on 4 wheels with driver
Turn ignition key to position '1' to release steering
lock.
Select neutral in main gearbox and transfer gearbox.
Secure tow rope, chain or cable to towing eye.
Release the handbrake.
The brake servo and power assisted steering
system will not be functional without the engine
running. Greater pedal pressure will be required
to apply the brakes, the steering system will
require greater effort to turn the front road
wheels. The vehicle tow connection should be
used only in normal road conditions, 'snatch'
recovery should be avoided.Suspended tow
To prevent vehicle damage, front or rear
propeller shaft MUST BE removed, dependent
upon which axle is being trailed.
Mark propeller shaft drive flanges at transfer box and
axles with identification lines to enable the propeller
shaft to be refitted in its original position.
Remove the propeller shaft fixings, remove the shaft
from the vehicle.
If the front axle is to be trailed turn ignition key to
position '1' to release steering lock.
The steering wheel and/or linkage must be
secured in a straight ahead position. DO NOT use
the steering lock mechanism for this purpose.
Towing eyes
The towing eyes at the front and rear of the vehicle
are designed for vehicle recovery purposes only and
must NOT be used to tow a trailer or caravan.
Front:A single towing eye, set behind a removable
panel in the front spoiler. DO NOT use the front
lashing rings for towing.

CAPACITIES, FLUIDS AND LUBRICANTS
09-2
Refrigerant - A/C system
Fluids
Anti-freeze
Use Havoline Extended Life Coolant (XLC), or any
ethylene glycol based anti-freeze (containing no
methanol) with only Organic Acid Technology
corrosion inhibitors, to protect the cooling system
CAUTION: No other anti-freeze should be used
with Havoline Extended Life Coolant.
The cooling system should be drained, flushed and
refilled with the correct amount of anti-freeze solution
at the intervals given on the Service Maintenance
Check Sheet.
After filling with anti-freeze solution, attach a warning
label to a prominent position on the vehicle stating
the type of anti-freeze contained in the cooling
system to ensure that the correct type is used for
topping-up.
Brake/Clutch fluid
Use only DOT 4 brake fluid.
PAS/ACE fluid
Use Texaco cold climate power assisted steering
fluid 14315.
Air conditioning
Use only refrigerant R134a.
Refrigerant oil
Use only NipponDenso ND-oil 8 or Unipart ND-oil 8.
Refrigerant oil absorbs water and must not be stored
for long periods. Do not pour unused oil back into the
container.
NOTE: The total quantity of refrigerant oil in the
system is 180 ml.
CAUTION: Do not use any other type of
refrigerant oil.

Refill3.4 pt

Fill from dry 3.6 pt
Cooling system - V8 Engine:

Refill24.2 pt

Fill from dry 26.2 ptComponent US Units

Front A/C 700 ± 25 g

Front/rear A/C 900 ± 25 g

MAINTENANCE
PROCEDURES 10-23
Power steering, suspension
ACE pipes
1.Check for fluid leaks from power steering and
suspension systems.
2.Check ACE pipes and unions for chafing, leaks
and corrosion and that all pipes and hoses are
correctly routed and secure.
Engine, gearbox, transfer box and axles
Check
1.Check for oil leaks from engine, gearbox
(manual and automatic), transfer box and front
and rear axles; pay particular attention to areas
around oil seals.
Exhaust system
Check
1.Check for signs of exhaust system leaks,
damage and security.
Steering box and front suspension
Check/tighten steering box fixings
1.Check steering box fixings and tighten to 90
Nm (66 lbf.ft).
Check/tighten front axle suspension fixings

MAINTENANCE
10-28 PROCEDURES
4.Check condition of Engine - RH mounting
rubber
5.Check tightness of all mounting bolts.

+ TORQUE WRENCH SETTINGS,
Engine V8.
Road/roller test
WARNING: Roller test must be restricted to 3
mph (5 km/h). If 2 wheel rolling road is to be used,
disconnect propeller shaft from the transfer box
output shaft driving the axle which is NOT on the
rolling road.Testing
1. 2 wheel rolling road: Engage differential lock
using a 10 mm open ended spanner on flats
machined on differential lock selector
shaft.Switch on ignition and check that the
differential lock, electronic brake
distribution and hill descent warning lamps
are illuminated.
2.Check for correct operation of starter switch,
ensure engine starts correctly; leave the engine
running.
3.Check for correct operation of starter switch,
ensure engine starts correctly; leave the engine
running.
4.With vehicle stationary, turn steering from lock
to lock. Check for smooth operation and ensure
there is no undue noise from power steering
pump or drive belt.
5.Depress clutch and select all gears in turn,
check for smooth, notch free engagement.
6. Check all vehicle systems for correct
operation.
7.Check for unusual engine, gearbox and
suspension noises.
8.Check braking system operation.
9.Check for smooth gear engagement.
10.Check engine performance.
11.Check operation of all instruments and warning
devices where practicable.

STEERING
DESCRIPTION AND OPERATION 57-5
Description
General
The major steering components comprise an impact absorbing telescopic steering column, a Power Assisted Steering
(PAS) box, a PAS pump, and fluid reservoir. Hydraulic fluid from the fluid reservoir is filtered and then supplied
through the suction line to the inlet on the PAS pump. The PAS pump supplies fluid to the steering box through a
pressure line routed above the front cross member. Fluid returns to the reservoir along the same route through a
return line. On LH drive vehicles the pipe route above the front cross member is still used, the length of pipe acting
as an oil cooler.
To minimise driver's injury in the event of an accident the steering system has a number of safety features including
a collapsible steering column. An additional safety feature is an air bag located in the steering wheel.

+ RESTRAINT SYSTEMS, DESCRIPTION AND OPERATION, Description - SRS.
Steering column assembly and intermediate shaft
The steering column central shaft comprises of two shafts, the upper shaft is splined to accept the steering wheel and
located in bearings in the column tube. A universal joint is located on the bottom of the upper shaft, the joint allows
for angular movement between the upper and lower shafts. The lower shaft is made in two parts, the top section of
the lower shaft is located outside of the lower section. The two sections of the lower shaft are connected by two nylon
injection moulded shear pins. The lower shaft goes through a lower bearing attached to the bulkhead, the lower shaft
is connected by a universal joint to the intermediate shaft in the engine compartment.
Steering column
An upper column tube provides for the location of the steering lock and ignition switch and also the steering switch
gear and a rotary coupler. The rotary coupler provides the electrical connection for the steering wheel mounted airbag,
switches and horn. The upper mounting bracket has two slots, a slotted metal bracket is held in each slot by four resin
shear pins.
The column is mounted on four captive studs which are located on a column mounting bracket. The captive studs
pass through the metal brackets, locknuts secure the steering column to the bulkhead. The two lower mountings are
fixed and cannot move when loads are applied to them. The upper mounting is designed to disengage or deform when
a load is applied, allowing the column to collapse in the event of an accident. The steering column must be replaced
as a complete assembly if necessary.
When an axial load is applied to the upper column tube, energy absorption is achieved by the following mechanism:
lthe mounting bracket deforms,
lthe resin shear pins holding the slotted metal brackets shear,
lthe top mounting bracket slides out of the slotted metal brackets.
The slotted metal brackets remain on the captive studs on the bulkhead. If the column mounting moves, injection
moulded shear pins retaining the two sections of the lower column shaft will shear. This allows the two sections of the
lower shaft to 'telescope' together.
In the event of a collision where the steering box itself moves, two universal joints in the column allow the intermediate
shaft to articulate, minimising movement of the column towards the driver. If movement continues energy absorption
is achieved by the following mechanism:
lthe decouple joint in the intermediate shaft will disengage,
lthe lower section of the steering column shaft will move through the lower bearing,
lthe injection moulded shear pins retaining the two sections of the lower column shaft will shear.
This allows the two sections of the lower shaft to 'telescope' together reducing further column intrusion. Protection to
the drivers face and upper torso is provided by an SRS airbag module located in the centre of the steering wheel.

+ RESTRAINT SYSTEMS, DESCRIPTION AND OPERATION, Description - SRS.

STEERING
DESCRIPTION AND OPERATION 57-9
Principle of operation
Movement of the input shaft is transferred through the pin to the torsion bar and valve rotor on the input shaft. As the
input shaft turns, the spline of the torsion bar turns the worm gear. This action causes the roller to rotate on its bearings
and move. As the roller is located by a pin to a yoke on the output shaft, the output shaft rotates in the steering box
housing. As the amount of torque acting on the input shaft increases the torsion bar starts to twist. As the torsion bar
twists the valve rotor turns in the valve sleeve. When the ports in the valve rotor and valve sleeve are turned, hydraulic
fluid is directed to chamber 'A' or 'B' in the power cylinder.
With hydraulic fluid in one chamber under high pressure, the piston moves. The return line ports in the rotary valve,
aligned by the movement of the valve rotor, allow the fluid in the opposite chamber to flow to return. The teeth of the
rack move and transfer the force from the piston to the output shaft, giving assistance to move the drop arm. As the
output shaft rotates the torsion bar load is decreased. The rotor on the input shaft will return as the torsion bar
unwinds, the rotary valve will then be in a neutral position and the pressure in chambers 'A' and 'B' will equalise. With
no high pressure acting on the piston, force on the piston and rack is released.
To prevent heat accumulation at full steering lock due to excessive pressure, a relief valve inside the steering box is
opened as the box approaches full lock. The relief valve pins are located in the cylinder cover and housing and are
not to be adjusted.
The steering box design ensures a mechanical link through the course spline on the control valve rotor, the spline will
become engaged if:
lThe hydraulic pressure fails.
lThe steering box rotary control valve fails.
The course spline may also engage in some full lock situations if sufficient torque is applied to the input shaft.
Rotary control valve
The rotary valve assembly comprises of three parts. The valve sleeve is fixed inside one end of the worm gear, the
valve sleeve has ports through it to allow the passage of hydraulic fluid. The input shaft has a valve rotor machined
on one end, the valve rotor also has ports through it and can rotate in the valve sleeve. A torsion bar is attached to
the input shaft by a pin, the torsion bar goes through the input shaft and valve rotor and is engaged by a spline into
the worm gear.
The course spline on the end of the valve rotor is loosely engaged in the worm gear, the course spline can make
contact and drive the worm gear in some full lock and in no pressure conditions. In the event of a torsion bar failure,
power assistance will be lost, the course spline will drive the worm gear and enable the vehicle to be steered and
driver control maintained.

STEERING
DESCRIPTION AND OPERATION 57-11
Rotary control valve in demand mode
1Worm gear
2Torsion bar
3Valve sleeve
4Pin5Input shaft and valve rotor
6Piston/rack
7Coarse spline
8Spline (torque shaft to worm gear)
When the steering wheel and input shaft is turned steering resistance transmitted to the worm causes the torsion bar
to be wound up and the valve ports in the valve rotor and valve sleeve to be aligned for a right or left turn. The
alignment of the valve ports directs fluid pressure 'A' from the PAS pump to one side of the piston/rack . The other
side of the piston/rack is now connected to return 'B' (due the valves port alignment) and displaced fluid returns to the
reservoir. The pressure difference in the cylinder on each side of the piston gives the power assistance to move the
rack and so turn the steering.
The greater the resistance of the road wheels to the steering rotary movement, the greater torque acting on the torsion
bar and input shaft causing greater changes of alignment of the ports in the valve. As the change of alignment
becomes greater, the fluid pressure passing to the applicable side of the piston/rack increases.
Only when the steering wheel stops turning and the torsion bar has unwound, will the valve rotor return to the neutral
position. In the neutral position the fluid circulates through the ports in the valve rotor and valve sleeve and back to
the reservoir where it is cooled.