1999 LAND ROVER DISCOVERY air filter

FRONT SUSPENSION
60-62 REPAIRS
9.Use LRT-60-009 to remove nut securing
actuator to long arm.
10.Remove nut and bolt securing actuator to short
arm and remove actuator.
CAUTION: The short arm and torsion bar
are supplied as an assembly and must not
be separated.Refit
1.Fit actuator to torsion bar. Use LRT-60-009to
tighten actuator to long arm nut to 48 Nm (35
lbf.ft). Tighten actuator to short arm nut and bolt
to 180 Nm (133 lbf.ft).
2.Ensure torsion bar mounting rubber mating
faces are clean and free from damage.
3.Fit mounting rubbers to torsion bar.
4.With assistance, position torsion bar and
actuator assembly to vehicle. Fit clamp plates
and tighten bolts to 45 Nm (33 lbf.ft).
5.Ensure washer is in place on lower ball joint of
each anti-roll bar link, then connect lower ball
joint to axle and tighten nuts to 100 Nm (74
lbf.ft).
6.Connect pipes to actuator with cap nuts and
new sealing washers. Tighten cap nuts to 29
Nm (21 lbf.ft). Ensure pipes are not under
tension or kinked.
7.Renew ACE high pressure filter.

+ FRONT SUSPENSION, REPAIRS,
Filter - high pressure - ACE.
8.Bleed ACE hydraulic system.

+ FRONT SUSPENSION,
ADJUSTMENTS, ACE hydraulic system
bleeding.
9.Fit RH front road wheel and tighten nuts to 140
Nm (103 lbf.ft).
10.Lower vehicle.

REAR SUSPENSION
DESCRIPTION AND OPERATION 64-9
DESCRIPTION AND OPERAT ION
SLS component layout
RH drive shown, LH drive similar
1Off-road mode switch
2SLS warning lamp
3Instrument pack
4Off-road mode warning lamp
5RH Height sensor
6RH Air spring7Air inlet filter
8LH Air spring
9LH Height sensor
10Air supply unit
11SLABS ECU

REAR SUSPENSION
64-14 DESCRIPTION AND OPERATION
The compressor is attached with Allen bolts to the motor housing and sealed with an O-ring. Attached to the
compressor is the air dryer which contains a silicate box for removing moisture from the compressed air. Air supplied
to inflate the air springs passes through the air dryer. When the air springs are deflated, the exhaust air also passes
through the air dryer, removing the moisture from the unit and expelling it to atmosphere.
Attached to end of the air dryer unit is the pressure limiting valve. The valve protects the air springs from over inflation.
The pressure limiting valve also operates when the exhaust valve is opened. The valve is pneumatically operated,
responding to air pressure applied to it.
The exhaust valve is also located with the pressure limiting valve. The exhaust valve is solenoid operated by the ECU
and directs air from the air springs and control valves to atmosphere when required.
The two air control valves for the LH and RH air springs are located at the forward end of the housing. Each valve is
connected to the compressor/air dryer unit through a shared single pipe which directs air to and from the air springs.
Each control valve is individually operated by the ECU.
All air connections to and from the air supply unit are made through the SLS air harness which is located along the
left hand chassis longitudinal.
If faults occur with the air supply unit, fault codes are stored in the SLABS ECU. These fault codes cover the
compressor power supply and the LH and RH air control valves and the exhaust valve. The current and past fault
codes can be retrieved with TestBook. TestBook can also be used to operate the compressor and the valves for
diagnostic purposes.
Air intake filter
The air intake filter is located in the left hand 'E' post, behind the tail lamp assembly. The filter comprises a plastic
moulded housing which contains two filters of differing density to remove particulate matter from the air drawn in by
the compressor. The air intake filter has a pipe which is connected to the SLS air harness by a quick release
connector. The air intake filter must be replaced as an assembly.
Air intake/Exhaust silencer
The air intake/exhaust silencer is located on the outside of the left hand chassis longitudinal, behind the air supply
unit. The silencer is an integral part of the SLS air harness and cannot be serviced individually.
The intake and exhaust air to and from the compressor passes through the silencer. The plastic moulded silencer has
two chambers. One chamber reduces system exhaust noise and the other dampens intake air pulses produced by
the compressor.

REAR SUSPENSION
DESCRIPTION AND OPERATION 64-21
Operation
Circuit diagram
1SLABS ECU
2Exhaust valve
3Restrictor
4Pressure limiting valve
5Silencer
6Inlet air filter
7Compressor
8Air dryer9Non-return valve
10RH air control valve
11RH air spring
12RH height sensor
13LH height sensor
14LH air spring
15LH air control valve
The SLS system is active when the ignition switch is in position II, when one or more doors are open and for up to
thirty minutes after all doors have been closed. If the rear axle is articulated by more than 100 mm (3.93 in), the ECU
will not activate the SLS system.
The air supply unit compressor will only operate to raise the rear of the vehicle when the engine is running, with the
exception of the remote handset operation which does not require the engine running. Three modes of SLS operation
are available; Normal Ride Height, Off-Road Mode (ORM) and Extended Mode. A fourth mode, transportation mode,
is programmed by TestBook for transport or recovery of the vehicle on a trailer.
Normal ride height
When the vehicle is stationary, a door is open and the ignition is off, the SLS system will allow the rear of the vehicle
to lower to within 20 mm of the normal ride height as load is removed from the vehicle. The SLS system will only
operate the compressor to raise the rear of the vehicle when the engine is running, unless requested using the remote
handset.

REAR SUSPENSION
REPAIRS 64-37
Filter - intake - SLS
$% 64.50.12
Remove
1.Remove LH tail lamp.

+ LIGHTING, REPAIRS, Lamp - tail.
2.Disconnect filter from retaining peg.
3.Disconnect quick release connection and
remove filter assembly.
Refit
1.Position filter assembly and connect quick
release connection.
2.Secure filter retaining peg.
3.Fit LH tail lamp.

+ LIGHTING, REPAIRS, Lamp - tail.
Switch - ride height
$% 64.50.45
Remove
1.Carefully remove switch.
2.Disconnect multiplug from switch.
3.Remove switch.
Refit
1.Connect multiplug switch.
2.Position switch and push to secure.

REAR SUSPENSION
64-40 REPAIRS
7.Use LRT-60-009 to remove nut securing
actuator push rod to long arm.
8.Remove nut and bolt securing actuator to short
arm and remove actuator.
CAUTION: The short arm and torsion bar
are supplied as an assembly and must not
be separated.Refit
1.Position actuator and tighten nut and bolt
securing actuator to short arm to 180 Nm (133
lbf.ft).
2.Using LRT-60-009 , fit and tighten nut securing
actuator push rod to long arm to 48 Nm (35
lbf.ft).
3.Connect pipes to actuator with cap nuts and
new sealing washers. Tighten cap nuts to 29
Nm (21 lbf.ft). Ensure pipes are not under
tension or kinked.
4.Connect anti-roll bar link to long arm and
tighten nut to 50 Nm (37 lbf.ft).
5.Ensure washer is in place on lower ball joint of
each anti-roll bar link and connect lower ball
joints to axle. Tighten nuts to 100 Nm (74 lbf.ft).
6.Renew ACE high pressure filter.

+ FRONT SUSPENSION, REPAIRS,
Filter - high pressure - ACE.
7.Lower vehicle.
8.Bleed ACE hydraulic system.

+ FRONT SUSPENSION,
ADJUSTMENTS, ACE hydraulic system
bleeding.

REAR SUSPENSION
REPAIRS 64-43
Refit
1.Clean bush locations in long arm.
2.Use suitable adaptors to press new actuator
rod end bush into long arm. Ensure bush is
correctly aligned.
3.Align slots in new slipper bush halves with
those in long arm. Carefully press both halves
of slipper bush into long arm. Ensure the
sealing rings on the bush faces are not
damaged.
4.Clean long arm and mating face on torsion bar.
5.Fit long arm to torsion bar. Restrain torsion bar
and tighten bolt to 180 Nm (133 lbf.ft).
6.Ensure actuator and bushes are clean.
7.Fit actuator and tighten nut and bolt securing
actuator to short arm to 180 Nm (133 lbf.ft).
8.Using LRT-60-009 , fit and tighten nut securing
actuator push rod to long arm to 48 Nm (35
lbf.ft).
9.With assistance, position torsion bar and
actuator to vehicle and fit torsion bar clamps.
Tighten torsion bar clamp bolts to 45 Nm (33
lbf.ft).
10.Connect pipes to actuator with cap nuts and
new sealing washers. Tighten cap nuts to 29
Nm (21 lbf.ft). Ensure pipes are not under
tension or kinked.
11.Fit anti-roll bar links to torsion bar and tighten
nuts to 50 Nm (37 lbf.ft).
12.Ensure washer is in place on lower ball joint of
each anti-roll bar link and connect lower ball
joints to axle. Tighten nuts to 100 Nm (74 lbf.ft).
13.Renew ACE high pressure filter.

+ FRONT SUSPENSION, REPAIRS,
Filter - high pressure - ACE.
14.Lower vehicle.
15.Bleed ACE hydraulic system.

+ FRONT SUSPENSION,
ADJUSTMENTS, ACE hydraulic system
bleeding.

BRAKES
70-6 DESCRIPTION AND OPERATION
Brake servo assembly
The brake servo assembly provides power assistance to reduce the pedal load when braking. If the brake servo
assembly fails, the hydraulic system still functions but will require greater brake pedal effort due to the lack of vacuum
assistance.
Two integral tie bolts attach the brake servo assembly to the pedal and bracket assembly on the engine bulkhead.
The master cylinder assembly is attached to the forward ends of the tie bolts.
The brake servo assembly consists of a circular housing which contains two diaphragms, a central plate, a control
valve assembly, input and output push rods and a filter. The input push rod is connected to the brake pedal. The output
push rod locates in the primary piston of the master cylinder. A protective gaiter is installed on the control valve
assembly where it extends from the rear of the housing. A non return valve, installed in a port in the front face of the
housing, is connected to a vacuum line from the engine.
The control valve assembly consists of a valve body containing a valve, a piston, a valve spring and an input rod
spring. The valve controls a vacuum port in the valve body. The piston controls an air inlet port between the valve and
the piston. A reaction disc and a ratio disc separate the piston from the output push rod. A guide tube on the front of
the valve body is attached to the front diaphragm and supported in a bush in the central plate. A return spring locates
in the open end of the guide tube.
The two diaphragms and the central plate separate the interior of the housing into four sealed chambers. The
chambers at the front of the diaphragms are connected together through fixed passages in the valve assembly. The
chambers at the rear of the diaphragms are connected together through the interior of minor diaphragms on the tie
bolts.
Brakes off
With the brake pedal released, the piston in the control valve assembly positions the valve so that the vacuum port is
open and the two pairs of chambers are connected together. When the engine is running air is evacuated through the
vacuum line and non return valve, creating a partial vacuum in all four chambers. When the engine stops, the non
return valve closes to maintain the partial vacuum and, on V8 models, prevent fuel vapour entering the brake servo.