power steering LAND ROVER DISCOVERY 1999 User Guide

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.

STEERING
57-16 DESCRIPTION AND OPERATION
Operation
Hydraulic fluid is supplied to the PAS pump inlet from the PAS reservoir, the PAS pump draws in and pressurises the
fluid. The PAS pump self regulates internal flow rates and operating pressure, and supplies pressurised fluid from the
PAS pump outlet to a rotary control valve in the steering box. At neutral the fluid is circulated by the PAS pump and
flows around the system at a lower pressure and a constant flow rate. With most of the fluid being returned to the
reservoir the pressure inside the system remains very low. When a control input turns the rotary control valve in the
steering box, pressure in the system will rise as the control valve directs fluid to give power assistance.
The action of turning the steering wheel turns the steering column and intermediate shaft. The intermediate shaft turns
the input shaft of the steering box. The input shaft moves the rotary control valve in the steering box, the rotary valve
controls the pressure used inside the steering box for power assistance. The input shaft also turns a worm gear, the
worm gear acts on a roller attached to the output shaft. As the worm gear turns the roller, the roller travels along the
lands of the worm gear. As the roller is attached to the output shaft the output shaft turns.
As the output shaft of the steering box turns, hydraulic pressure is supplied via the rotary control valve to the steering
box. The hydraulic pressure acts on a rack that assists with the movement of the output shaft of the steering box. A
drop arm is attached to the output shaft of the steering box. The drop arm is connected to a drag link by a ball joint.
The drag link is connected via ball joints to one front steering knuckle and road wheel. A track rod connected to this
steering knuckle links the two steering knuckles together. As one steering knuckle and road wheel is turned by the
drag link, the other steering knuckle and wheel is moved by the track rod.

STEERING
57-18 ADJUSTMENTS
Hydraulic system - bleed
$% 57.15.02
Bleed
1.Clean PAS fluid reservoir around filler cap and
fluid level indicators.
2.Remove filler cap from PAS fluid reservoir. If
necessary, fill PAS fluid reservoir to upper level
indicator with recommended fluid.

+ CAPACITIES, FLUIDS,
LUBRICANTS AND SEALANTS, Fluids.
CAUTION: Ensure no dirt is allowed to enter
the steering reservoir when the cap is
removed.
3.Start engine and run to normal operating
temperature.
4.Position container to catch fluid spillage from
steering box.
5.With engine at idle speed, and an assistant
turning the steering from lock to lock, loosen
bleed screw on top of steering box. Keep PAS
fluid reservoir topped up and allow all air to
bleed from system. When fluid from bleed
screw is free of air, tighten bleed screw.
CAUTION: Do not hold steering at full lock
for longer than 10 seconds.
6.Stop engine.
7.Clean spilled PAS fluid from steering box and
surrounding area.
CAUTION: Power steering fluid will damage
paint finished surfaces. If spilled,
immediately remove fluid and clean area
with water.
8.Check fluid level in PAS fluid reservoir and fill to
upper level mark. If fluid is aerated, wait until
fluid is free from bubbles.
9.Fit PAS fluid reservoir filler cap.
Steering linkage - centralise
$% 57.35.05
The following procedure assumes that the front
wheel alignment is correctly adjusted.
Adjust
1.Raise front of vehicle, and position the road
wheels at straight ahead.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove nut securing drag link to drop arm.
Using tool LRT-57-036 break taper joint and
release drag link from drop arm.
3.Fit centralising bolt to steering box and ensure
that front road wheels are in the straight ahead
position.
4.Loosen clamp bolts on drag link.

STEERING
57-20 ADJUSTMENTS
Power steering pressure check - diesel
models
$% 57.90.10.01
Check
1.Fit gauge and hose LRT- 57-005 to valve
assembly LRT- 57-001 and tighten union.
2.Fit 2 hoses LRT-57-002 to valve assembly
LRT- 57-001 and tighten unions
3.Fit adaptor and hose set LRT-57-041 to LRT-
57-002.
4.Disconnect battery earth lead.
5.Remove engine acoustic cover.
6. LHD only: Remove underbelly panel.

+ EXTERIOR FITTINGS, REPAIRS,
Panel - underbelly.7. LHD only: Disconnect MAF sensor multiplug,
release clips from air cleaner and move intake
hose aside. Discard seal.
8.Position container to collect PAS fluid spillage,
and syphon fluid from PAS reservoir.
9. LHD only: Release PAS reservoir from
mounting move aside, for access to
turbocharger intercooler pipe.
10.Remove vacuum hose from turbocharger
intercooler pipe.
11. LHD only: Release clips and disconnect
turbocharger intercooler pipe from
turbocharger and intercooler.
12.Clean steering box pipe housing.
M57 0902
M57 0903
M57 0904

STEERING
57-22 ADJUSTMENTS
38.Fit new seal, connect PAS cooler pipe and
tighten union nut to 24 Nm (18 lbf ft).
39. LHD only: Fit turbocharger intercooler feed
pipe and vacuum connection. Fit new seal to air
cleaner. Connect air intake hose and secure
clips. Connect multiplug to MAF sensor.
40.Clean chassis and surrounding area.
41.Fit underbelly panel.

+ EXTERIOR FITTINGS, REPAIRS,
Panel - underbelly.
42.Remove adaptor and hose set from tool LRT-
57-041.
43.Check PAS fluid level.
44.Connect battery earth lead.
Power steering pressure check - V8 LHD
models
$% 57.90.10.01
Check
1.Disconnect battery earth lead.
2.Syphon PAS fluid from reservoir.
3.Raise front of vehicle and support on stands.
4.Turn steering on LH lock.
5.Remove 3 screws securing LH splash shield
and remove shield.
6.Release clip securing PAS pipes.
7.Position absorbent cloth to catch spillage.
8.Position container to collect PAS fluid spillage.

STEERING
57-24 ADJUSTMENTS
33.On completion stop engine, disconnect battery
earth lead and syphon fluid from PAS reservoir.
34.Remove test equipment from LRT-57-002.
35.Clean PAS pump and pipe union.
36.Fit new 'O' ring to high pressure pipe, align to
PAS pump and tighten union to 25 Nm (18
lbf.ft).
37.Secure PAS pipes in clip.
38.Using new 'O' ring fit intake hose to air cleaner
and secure clips.
39.Remove PAS reservoir filler cap, fill to level
indicator and refit cap.
40.Connect battery earth lead.
41.Start engine and allow air to bleed from PAS
system, by turning steering from lock to lock.
42.Visually check PAS system for leaks.
43.Clean chassis member.
44.Check power steering fluid, if aerated, wait until
fluid is free from bubbles then top-up reservoir
to 'UPPER' level mark.
45.Lower vehicle.
46.Dismantle test equipment.
Power steering pressure check - V8 RHD
models
$% 57.90.10.01
Check
1.Fit gauge and hose LRT-57-005 to valve
assembly LRT-57-001, tighten union.
2.Fit 2 hoses LRT-57-002 to valve assembly
LRT-57-001 and tighten unions.
3.Fit adaptor hoses LRT-57-041 to LRT-57-002
and tighten unions.
4.Disconnect battery earth lead.
5.Remove 5 screws securing front splash shield
to chassis. Remove shield.
6.Clean PAS fluid reservoir around filler cap and
fluid level indicators.

STEERING
ADJUSTMENTS 57-25
7.Syphon PAS fluid from reservoir.
8.Position container to collect PAS fluid spillage.
9.Clean steering box pipe pipe housing.
10.Remove bolt securing pipe clip to steering box.
Leaving the feed pipe from PAS reservoir in
place, release clip and PAS cooler pipe from
steering box. Discard lower 'O' ring.
11.Fit LRT-57-041 adaptor to steering box.
12.Fit PAS cooler pipe to LRT-57-041, align
retaining clip and tighten Allen bolt to 25 Nm (18
lbf.ft).
13.Hang pressure gauge in a safe position under
bonnet.
14.Remove PAS reservoir filler cap, fill to level
indicator and refit cap.
15.Connect battery earth lead.
16.Start engine and allow air to bleed from PAS
system by turning steering from lock to lock.
Stop engine and check PAS fluid level.
17.Ensure steering system and test equipment are
free from leaks.
18.Open test valve on LRT-57-001 and start
engine.
19.With the engine at idle, slowly turn the steering
wheel and hold on full lock.
20.Note the pressure reading on LRT-57-005.21.Repeat the pressure check for the opposite full
lock.
22.Test pressure should be between 21 and 62
bar, (300 to 900) psi. Dependant on road
surface.
23.With the engine at idle, centralise the steering
wheel. Pressure should read 7 bar (100 psi) or
below.
24.Pressure outside the above tolerance indicates
a fault.
25.To determine if fault is in steering pump or
steering box, close the valve on LRT-57-001 for
a maximum of 5 seconds. Pump damage may
occur if test valve is closed for longer periods.
26.If gauge does not register between 75 and 103
bar, (1500 psi), (maximum pump pressure), the
pump is faulty.
27.If maximum pump pressure is correct suspect
the steering box.
28.On completion stop engine, disconnect battery
earth lead and syphon fluid from PAS reservoir.
29.Remove test equipment from LRT-57-002.
30.Remove bolt and clip from steering box.
31.Release PAS cooler pipe from LRT-57-041 and
discard 'O' ring. Leaving PAS reservoir oil feed
pipe in place, release LRT-57-041 from
steering box and discard 'O' ring.
32.Fit new 'O' rings to PAS cooler pipe.
33.Fit PAS cooler pipe to steering box, align
retaining clip, fit bolt and tighten to 25 Nm (18
lbf.ft).
34.Remove PAS reservoir filler cap, fill to level
indicator and refit cap.
35.Clean chassis member.
36.Fit splash shield and secure with screws.
37.Connect battery earth lead.
38.Start engine.
39.Start engine and allow air to bleed from PAS
system, by turning steering from lock to lock.
40.Visually check PAS system for leaks.
41.Check power steering fluid, if aerated, wait until
fluid is free from bubbles then top-up reservoir
to 'UPPER' level mark.
42.Visually check PAS system for leaks.
43.Dismantle test equipment.

STEERING
REPAIRS 57-27
REPAIRS
Power steering box - V8
$% 57.10.01
Remove
1.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove front road wheel.
3.Ensure steering wheel is centralised and fit
centralising bolt to steering box. Remove key
from steering lock and engage column lock.
4.Remove 3 bolts securing intermediate shaft
and universal joint.
5.Push intermediate shaft upwards, release and
remove universal joint.
CAUTION: Do not turn the steering wheel
with the intermediate shaft or universal joint
disconnected as damage to the rotary
coupler and the steering wheel switches
may occur.
6.Position container to catch oil spillage.

STEERING
57-30 REPAIRS
Power steering box - LHD - diesel
$% 57.10.01
Remove
1.Remove battery cover.
2.Disconnect battery earth lead.
3.Drain cooling system.

+ COOLING SYSTEM - Td5,
ADJUSTMENTS, Drain and refill.
4.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
5.Remove LH front road wheel.
6.Ensure steering wheel is centralised, remove
key from steering lock and engage column lock.
7.Fit centralising bolt to steering box.
8.Loosen 2 clips securing intercooler to turbo
hose. Remove hose.9.Remove 3 bolts securing intermediate shaft
and universal joint.
10.Push intermediate shaft upwards, release and
remove universal joint.
CAUTION: Do not turn the steering wheel
with the intermediate shaft or universal joint
disconnected as damage to the rotary
coupler and the steering wheel switches
may occur.
11.Position container below PAS pipes to catch
fluid spillage.

STEERING
REPAIRS 57-37
Refit
1.Fit centralising bolt to steering box.
2.With assistance, position steering box to
chassis, fit bolts and tighten to 90 Nm (66 lbf.ft).
3. Models with ACE: Ensure washer is in place
on lower ball joint of anti-roll bar link, then
connect lower ball joint to axle and tighten nut
to 100 Nm (74 lbf.ft).
4.Position drag link, fit nut and tighten to 80 Nm
(59 lbf.ft).
5.Position Panhard rod, fit bolt and nut and
tighten to 230 Nm (170 lbf.ft).
6.Position coolant rail and secure with clips and
bolt.
7.Fit coolant hoses and secure with clips.
8. Models with ACE: Fit and tighten bolt
securing ACE pipes to chassis.
9.Clean PAS pipes ends and 'O' ring recess.
10.Lubricate new 'O' rings for PAS pipes with
clean PAS fluid.
11.Fit 'O' rings to PAS pipes and position pipes in
steering box. Fit PAS pipe bracket and tighten
bolt to 22 Nm 16 lbf.ft).
12.Ensure steering wheel is centralised. Fit
universal joint between steering box and
intermediate shaft and tighten bolts to 25 Nm
(18 lbf.ft).
13.Remove centralising bolt from steering box.
14.Fit road wheel(s) and tighten nuts to 140 Nm
(103 lbf.ft).
15.Remove stand(s) and lower vehicle.
16.Connect battery earth lead.
17.Fit battery cover.
18.Refill cooling system.

+ COOLING SYSTEM - Td5,
ADJUSTMENTS, Drain and refill.
19.Bleed PAS system.

+ STEERING, ADJUSTMENTS,
Hydraulic system - bleed.
20.Centralise steering linkage

+ STEERING, ADJUSTMENTS,
Steering linkage - centralise.
Seal - input shaft - steering box
$% 57.10.16
Remove
1.Remove steering box:
lFor V8 models:

+ STEERING, REPAIRS, Power
steering box - V8.
lFor LHD diesel models:

+ STEERING, REPAIRS, Power
steering box - LHD - diesel.
lFor RHD diesel models:

+ STEERING, REPAIRS, Steering
box - RHD - diesel.
2.Secure steering box in vice.
3.Remove circlip and extract oil seal from
steering box. Take care not to damage
surface of the shaft.
Refit
1.Clean oil seal recess and input shaft.
2.Lubricate new seal with clean PAS fluid.
3.Fit seal using LRT-57-503.
4.Fit circlip.
5.Fit steering box.
lFor V8 models:

+ STEERING, REPAIRS, Power
steering box - V8.
lFor LHD diesel models:

+ STEERING, REPAIRS, Power
steering box - LHD - diesel.
lFor RHD diesel models:

+ STEERING, REPAIRS, Steering
box - RHD - diesel.