1994 JAGUAR XJ6 steering

With the vehicle travelling straight ahead, the valve restrictions are balanced, thus providing equal pressure on each
side of the piston. When load is applied at the steering wheel the two halves of the pinion valve are displaced making
the restrictions unequal. The differential pressure then directs the rack piston in favour of the higher pressure.
Asthe turning load is removed the pressures equalize and the steering returns to the straight ahead position, aided by suspen-
sion geometry.
The displacement
of the halves of the pinion valve (rotor and sleeve) is controlled by the elastic deformation of the
torsion bar which is concentric with the pinion and valve.
0 N
J Outlet K Outlet
L Inlet
M Inlet
N Radial groove (return)
0 Radial groove (feed) P Feedgroove ~57-278 Q Axial groove
R Axial groove S Return groove
Fig.1 Porting & hydraulic flow - LOW speed clockwise rotation
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@ Steering
The rotaryvalve within the pinion housing on the 'Servotronic'system is fitted with a 'Hydraulic Reaction Piston' (HRP). The HRP moves axially, relative to the rotor, on ball bearing travellers (acting as a face cam) and is connected to the
sleeve
by a four bearing helical screw. Pressure applied eitherside of the HRP is translated into a rotational force which
resists torsion bar /valve displacement thus increasing steering effort. The amount of pressure applied to the HRP is
controlled by: a) the differential pressure on the rack piston, proportional tovehicle corneringforce and
b) the position
of the transducer valve controlled bythe SCM from information gathered on road speed. Road speed data is processed
from the left hand rear wheel speed sensor.
1 Electronic speedometei
2 SCM 3 Transducer 4 Reaction area 5 Reaction area
6 Checkvalve 7 Checkvalve
8 Choke 9 Choke
10 Reaction limitina valve 157-279 11 Reaction piston-
N Radial groove (return)
0 Radial groove (feed)
Fig.1 Sensors, valves & hydraulic flow - HIGH speed anti-clockwise rotation
X300 VSM Issue 1 August 1994 4

10.2 SERVICE
PROCEDURES - SAFETY RELATED
10.2.1
Airbag
The electrically activated driver's side airbag is attached to the steering wheel hub and is fed by two wires from the
column stalk assembly. Electrical input to the column stalk assembly for the airbag is provided by a dedicated harness
which is encased in a yellow sleeve. A mechanism in the stalk assembly called the 'cable reel cassette' provides conti
-
nuity from the static column to the steering wheel. The 'cable reel cassette' is driven by a tang which locates in the
steering wheel. Because the connection is by wires, and the cassette assembly is only capable of approximately five
(5) full turns,
it is critically important that initial positioning is correct, see Section 15. It is equally important that fitting of the steering wheel, connection of the column, lower shaft and steering rackshould
ONLY be made with the steering rack in the center of its travel.
WARNING: DO NOT REMOVE THE STEERING COLUMN FROM THE VEHICLE WITH THE STEERING WHEEL AT- TACHED UNLESS THE STEERING IS CENTERED AND THE COLUMN LOCK IS ENGAGED. IF THE LOCK
BARREL
IS TO BE RENEWED, 'LOCK-WIRE THE ASSEMBLY TO PREVENT ROTATION. FAILURE TO OB- SERVE THIS AND CONSEQUENT DAMAGE TO THE 'CABLE REEL CASSETTE MAY RESULT IN AN INOP- ERATIVE AIRBAG SYSTEM. SEE LABEL ON STEERING WHEEL HUB.
10.3 SERVICE PROCEDURES
10.3.1 Working Practices
It is not recommended that either the steering rack or engine driven pump assemblies are repaired in any way other
than in accordance with the repair procedures described in this manual. The fluid reservoir and filter is a disposable
assembly and no attempt should be made to clean it internally. Genuine replacement units must be fitted following
routine service or diagnostic confirmation of the failure of any component.
The importance of cleanliness cannot be over
-stressed, not only with new parts but also those which may havefailed.
In-service contamination of the hydraulic system is a major cause of failures and may be avoided with good working
practices and care. All new units and pipes must be supplied with suitable blanks in every orifice. Should a unit not
have blanks fitted, do not use
it - return it to the supplier with an appropriate reason for your action.
To help the manufacturer diagnose problems and avoid post-removal contamination; provide full details of the fault
and plug all connections as soon as they are released. All suspect units must be returned to Jaguar Cars complete
with relevant documentation.
CAUTION: It is imperative that the power steering system does not become contaminated in any way. Always de- cant fluid from afresh sealed container and clean the area around the reservoir neck both before and after topping-up. Never return drained fluid to the system.
10.3.2
Position the vehicle on a level surface with the engine sta- tionary and fluid cold. Add fluid, if required, so that the level
falls BETWEEN the marks
Fig.1.
10.3.3 System Bleed (following maintenance)
To avoid fluid aeration and possible pump damage, the in- itial fill process must be carried out with the ignition OFF.
Set the fluid level approximately 20 mm above the upper
dipstick level, and cycle the steering no less than three (3) times from lock to lock (this may be best achieved with the
front wheels off the ground). As air is expelled thefluid level
will fall, the level should be corrected. Start the engine and
further cycle thesteering until the fluid level becomes stable.
Stop the engine and finally set the level in accordance
with the fluid level check procedure.
10.3.4 Fluid Reservoir
The reservoir has an integral, non-serviceable, return-side
filter. Should any component be renewed or the system
'broken into' for any reason,
it is essential that the reservoir and the fluid are changed. Under normal operating condi- tions it is not necessary to change the fluid.
10.3.5 Hydraulic Connections
Fluid
Level Check and
Top-up
Jf7-281
Fig. 1
All hydraulic connections and surrounding areas should be scrupulously cleaned before and after work. Please note
that the steering rack valve block connections for FEED and RETURN are common in size. Ensure that the pipes are
correctly fitted, the uppermost one being the high pressure FEEDfrom the steering pump and the lower (RETURN) hav- ing a double depth hexagon tube nut.
X300 VSM 5 issue 1 August 1994

@ Steering
Cause
Fluid level low?
Drive belt slack
(V12)
Pump drive loose (6cyl)
center pressures low
Air in system due to loose connection
Pump shaft seal faulty (fluid loss)
Delivery pressure or flow too low
Return flow restricted by blocked reser
-
voir filter
Both check valves blocked
Rack damper too
tight
Lower column incorrectly set
Excessive upper column friction
Faulty rotary valve or seal
Drive belt slack
(VI217
Engine idle speed too low
Pump drive loose
(6cyl)
Air in system due to loose connection
Pump shaft seal faulty (fluid
loss)
Delivery pressure or flow too low
Fluid level low?
tire pressures
high
Air in system due to loose connection
Stiff or seized steering joint
Rack damper too tight
Castor or tracking error
Lower column over extended
Fluid level low?
Air
in system due to loose connection
Pump shaft seal faulty (fluid
loss)
Rack damper loose
Pinion bearing faulty
Rack or column fixings loose
Rack mounting bracket loose
Rack mounting bush loose
Free play in column assembly
10.4 DIAGNOSTIC PROCEDURE
10.4.1 Introduction
The following diagnostic procedures are provided to rapidly pin-point mechanical faults which are not interrogated
by electrical means. Diagnostic procedures which require dedicated electrically operated equipment are dealt with in the 'Electrical Diagnostic Manual' (EDM) but may be mentioned here for reference.
10.4.2 Preliminary Action
Before any problem solving is undertaken it is essential that the fluid level and where applicable, belt tension, is
checked and if required corrected.
CAUTION: It is imperative that the power steering system does not become contaminated in any way. Always de cant fluid from a fresh sealed container and clean the area around the reservoir neck both before and after
topping-up. Never return drained fluid to the system.
10.4.2 Diagnostic Chart 1
Remedy
Rectify fluid loss and or top up
Re
-tension belt
Renew pump
Set to specification
Secure connection and bleed air out
Renew pump
Renew pump
Renew reservoir
Renew rack
Renew rack
Set to specification
Renew upper column
Renew rack
Retension belt
Reset idle speed
Renew
pump
Secure connection and bleed air out
Renew
pump
Renew pump
Rectify
fluid loss and or top up
Set to specification
Secure connection and bleed air out
Test and renew faulty joint
Renew rack
Check geometry and rectify
if required
Set to specification
Rectify fluid
loss and or top up
Secure connection and bleed air out
Renew pump
Renew rack
Renew rack
Tighten to specification
Renew rack
Renew rack
Check and rectify as required
Trouble
Heavy on both sides
Heavy on one side
Heavy when steering
rapidly
Vague feel about center
Knocking
1 vibration felt
at steering wheel
0
0
0
0
Issue 1 August 1994 6 X300 VSM

10.4.3 Diagnostic chart 2
0 Trouble
'lay at steering wheel
ieavy when stationary
Excessively heavy when
hiving, stationary effort
3K
Too easy when driving,
itationary effort OK
fffort not equal side to
;ide from center
dariation from heavy to
?asy when driving
:yclic load variation at steering wheel - 2 per
.evolution
:losely spaced cyclic
oad variation at steering
Nheel
Cause
Rack damper loose
Pinion bearing loose
Worn intermediate shaft joint
Worn suspension joint
Loose lower column 'pinch' bolt
Transducer not closed
Transducer not closed
- ground short
Transducer not closed
- no feed voltage
Transducer not closed
- defective cable
SCM defective
Delivery pressure or flow too low
Internal rack leakage
tire pressures low
Transducer open too early
Transducer open too early, incorrect SCM
h/Pe
Transducer open too early, incorrect
speedometer signal
Rack 'reaction limitation valve' CLOSED
or setting incorrect
Transducer not open (no oil flow)
Transducer not open, SCM faulty
Transducer not open, incorrect speedom
-
eter signal
Rack 'reaction limiting valve' OPEN or
setting incorrect
Low pressure pipe 'flattened' or re
-
stricted
Blocked reservoir filter
tire pressure high
Rack check valve leak
Rotary valve blockage Incorrect lower column assembly, see
'Cyclic load variations'
Incorrect speedometer signal
Transducer cable
/ connection faulty or
grounded
Lower column universal joint fitting error
Rack damper too tight
Remedy
Renew rack
Renew rack
Renew joint
Renew joint
Tighten to specification
Inspect and check for debris
Renew transducer*
Investigate and repair
Renew cable
Renew module*
Renew pump
Renew rack
Set to specification
Renew transducer*
Renew
SCM*
Renew speedometer transmitter*
Renew rack
Inspect and check for debris
Renew
SCM*
Renew speedometer transmitter*
Renew rack
Renew pipe
Renew filter
Set to specification
Renew rack
Renew rack
Rectify as required
Renew speedometer transmitter*
Investigate and repair
Verify that the lower column assembly is
correct for that drive.
RH and LH assem- blies MUST NOT be interchanged due to
joint phase differences
Renew rack
W: Items marked * should be validated using EDM test procedures.
X300 VSM 7 Issue 1 August 1994

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10.4.4 Diagnostic chart 3
Trouble
Hydraulic noise when
turning lock to lock
Continuous pressure
relief valve operation
Continuous noise
Cause
Fluid level low?
Air ingress at connections
Air ingress through feed hose lining
or
skin
Air ingress at pump front seal
Water contamination caused by fractured
cooler pipe within engine coolant radi
-
ator
Pump starvation or cavitation caused by
twisted or trapped feed hose
Pump starvation caused by blocked filter
Worn
pump
High pressure hose (pump to rack) dam-
aged or restricted
Fluid level low?
Drive belt loose
(12 cyl only)
Drive pulley loose
Steering pump mounting
(4 loose
Drive 'dog' loose, slipping or incorrectly
fitted
(6 cyl only)-
Hose or pipe fretting on body or chassis
structure
Hose twisted or restricted
Remedy
Rectify fluid loss and or top up
Check and tighten all connections to spec
-
ification
Renew faulty
'0' rings or Dowty washers
Renew porous
1 damaged hoses
Renew
pump
Renew radiator. Flush and drain steering
system twice
minimum, check for noise
and system performance (Pump is most
susceptible to damage due to
loss of lu-
brication and may have to be renewed)
Reroute or relieve pressure
Renew reservoir
Renew pump
Renew hose
Rectify
fluid loss and or top up
Inspect for damage and renew as required
Tighten pulley to specification
Tighten to specification
Investigate
& rectify as required
Rectify routing
Rectify routing
Issue 1 August 1994 8 X300 VSM

10.5 OUTER
TRACK ROD BALL JOINT, RENEW
sRo . Disconnect 57.55.02 vehicle battery ground lead.
. Raise the front of the vehicle and remove the appropriate
road wheel
Slacken the track rod
locknut but do not wind away from
the ball joint (1 Fig. 1).
m: Leave the lock-nut in its original position to initially
locate the new ball joint.
. Remove the track rod ball joint nut (and discard) (2 Fig. 1)
at the steering arm (3 Fig. 1).
. Using service tool JD 100 (1 Fig. 2), release the taper and
remove the ball joint (2 Fig. 2).
Fit the new track rod ball joint up to the lock-nut and se- cure at the steering arm with a new nut; tighten to specifi- cation.
. Fitting is the reversal of this procedure noting that the sus- pension should be fully settled prior to tracking adjust-
ment.
0 10.6 FRONT HUB ASSEMBLY, RENEW
SRO 60.25.01
10.7
SRO 60.25.12
10.8 FRONT HUB BEARING, RENEW
SRO 60.25.16
10.9
SRO 60.25.17
Disassemble
Disconnect vehicle battery ground lead.
. Support the vehicle at the front and remove the appropri-
. Remove brake caliper and disc assemblies see SRO 70 10
IWQ: Do not allow thecaliperto hang by either harness or
flexible hose.
FRONT HUB BEARING END FLOAT, CHECK
AND ADJUST
FRONT HUB
OIL SEAL, RENEW
ate road wheel (s)
10, section 12 for removal method only.
WARNIM: DO NOT INHALE BRAKE PAD DUST, ITMAY DAM-
0
AGE YOUR HEALTH.
. Prise of the hub grease cap (1 Fig. 3).
Remove and discard cotter pin (2 Fig. 3), pull off castel- lated nut retainer (3 Fig. 3).
Remove the hub nut and bearing washer.
Carefully remove the hub assembly (4 Fig. 3)fromthestub axle.
Hub oil seal. Prise the original seal from the spigot and dis-
card.
. Remove all traces of grease and dirt from the stub axle and
back plate.
. Lightly lubricate the stub spigot (to ease assembly of the
seal) and assemble the seal tothe spigot using special tool JD 179 (Fig. 4).
JS7-i 58 Fig. 1
Fig. 3
Fia.
4
X300 VSM 9 Issue 1 August 1994

@ Steering
. Pack the annular gaps of the oil seal lips with grease.
. Bearing. Wash the hub assembly thoroughly and 'drift' the affected bearing cup(s) from the hub.
!&!$Q:
rn Hub. At this point the hub may be renewed if required.
Assembly
. Bearing. Assemble the inner bearing track to the hub using service tool 18G 134 and adaptor JD 550 - 5 / 1.
Ensure that the hub inner seal diameter is free of debris or damage and is lightly lubricated prior to assembly.
Only replace complete bearings, never cup or race in isolation.
Assemble the outer bearing cup to the hub using service tool
18G 134 and adaptor JD 550 - 5 / 2. Pack each race with approximately 4 ml of grease and position the inner race onto the stub axle.
Apply a smear of grease to hub inner surfaces and bearing cups. Assemble the hub to the stub axle followed by
outer race, bearing washer and hub nut.
It is not necessary to fill the hub cavity with grease, merely protect from corrosion with a coat of IubricanL'Seat'the bear-
ings by slightly tightening the hub nut whilst rotating the hub. Do not apply load without rotation. m:
. End float. Set a Dial Test Indicator (DTI) as shown in Fig. 1 and adjust the hub nut to achieve the correct end float.
As the adjustment is made, continually load the hub axial-
ly in both directions.
. Without disturbing the end float setting, fit the castellated
nut retainer so that it aligns with both hub nut and stub
axle drilling.
. Secure nut retainer using a new cotter pin.
9 Assembly and fitting is the reversal of this procedure not- ing that; all fixings MUST be tightened to specification
and operation of the braking system verified.
Fig. 1
Issue 1 August 1994 10 X300 VSM