1998 JAGUAR X308 Pas pump

High
-pitched sound like rubbing a clean window.
Squea

l
Continu
ous, high-pitched sound like runn
ing finger nails across a chalkboard.
Tap
Ligh
t, hammering sound like tapping pencil on edge
of table. May be rhythmic or intermittent.
Weep
Continu
ous mid-range sound (lower frequency
than squeal, higher frequency than groan).
Whir/
Whine
High
-pitched buzzing sound, like
an electric motor or drill.
Whistle

Sharp, shril
l sound, like wi
nd passing a small opening.
Description of Specific St eer
ing System Noise Types
Bel
t Squeal
Belt squea
l is a high frequency air-born
e noise generated by slippage of the ribbe d Vee belt on the power steering pump
pulley. Squeal increases with system loading and at the end of lock.
Clonk

Cl
onk is a structure-borne nois
e heard as a loose-sounding rattle or vibration coming from the steering column. Clonk can
be identified by driving and turning over cobblestones, rough roads, or high frequency bumps such as 25-50 mm tall tar
strips. Clonk requires a tie-rod load impact.
Column Knoc
k
Col
umn knock is a loose-sounding rattle or
vibration generated by the steering column shaft contacting other portions of the
column assembly. The noise is both audible and tactile. Column knock is generate d by driving over cobblestones or rough
pavement. It is not necessary to turn the steering wheel to create this noise.
Column Ra
ttle
Co
lumn rattle is a metallic sounding no
ise created when applying a highly impuls ive force to the steering wheel. Column
rattle is often used to combine the more general group of column noises includin g clonk and column knock. Column rattle
noises can be caused by clonk, knock, l oose column components, bonus parts etc. A series of parked, straight-line driving,
and cornering test should be carried out to isolate the source/sources.
Gr
inding/Scrape
Gr

inding is a low frequency noise in the column when the st
eering wheel is turned. Is generally caused by interference
between moving components such as the st eering wheel to steering column shroud.
Gr
unt (Squawk)
Grunt

is a "honking" sound elicited when coming off one of
the steering stops. Grunt is generally excited during parking
manoeuvres with a low to me dium speed steering input.


Squea
k

Hiss (Swish)
Hiss or Val
ve Hiss is a high-frequency so
und coming from the steering gear when the system is loaded. It is a rushing or
"swish" noise that doesn't change frequency with RPM. Hiss is the general noise generated by the flow of hydraulic fluid
through restrictions in the steer ing system. Restrictions include the rotary stee ring valve, power steering tubes, connectors,
tuning orifices, etc. Hiss can be air- borne and structure-borne, but the structure-borne path through the steering
intermediate shaft is usually dominant.
Moan (Groan)
Moan is the general structu r
e-borne noise of the steering system. Moan is primarily transmitted to the driver via the body
structure through the pump mount, engine mounts, power steering lines and power steering brackets. On some vehicles,
moan is a load humming noise, often present when the wheel is turned and the system is loaded. It may change frequency
with engine RPM and if the sy stem is loaded or unloaded.
Rack Knock (R
ack Slap)
CAU
T
ION: DO NOT attempt to adjust the stee
ring gear yoke. Failure to follow this instruction will result in the steering
gear warranty to become invalid.
Rack Knock is a rattle sound an d steering wheel vibration caused by separation of the steering gear and pinion while driving
over bumps. It is a structure-borne noise transmitted throug h the intermediate shaft and column. Rack knock can also be
heard as a "thump" or impact noise that occurs with the vehicle stationary when the steering wheel is released from a
loaded position and allowed to return to rest . Noise occurs with the engine on or off.
Rattles
Ra
ttles are noises caused by knocking or hitting with components in the steering system. Steering rattles can occur in the
engine compartment, the suspension, or the passenger compartment . Rattles can be caused by loose parts, movable and
flexible parts, and improper clearances.
Squea k
s/Scrapes
Squeaks/Scrapes are noises due
to fri
ction or component rubbi
ng anywhere in the steering system. Squeaks/Scrapes have
appeared in steering linkages and jo ints, in column components and in co lumn and steering wheel trim parts.
Weep
We
ep is an air-borne noise, occasionally
generated when turning the steering across lock at a constant rate. When present
on a vehicle the noise, once initiated can often be maintained across a large proportion of the available steering movement.
Whistle
Wh
istle is similar to hiss but is louder and of a higher frequency. It is also more
of a pure tone noise than hiss. Whistle is
air-borne and is generated by a high flow rate of hydraulic fluid through a small restriction.
Zip

Zip n
o
ise is the air-borne noise
generated by power steerin g pump cavitation when power steering fluid does not flow freely
through the suction hose from the rese rvoir to the pump. Zip primarily occurs during cold weather at start-up.
Steering System Vibrations and Harshne
ss
Buzz
Buzz is a tactile rotary vi

bration felt in
the steering wheel for slow steering inputs. Buzz can also be called a grinding feel
and it is closely related to grunt and is caused by high system gain with low damping. Buzz is generally excited during
parking manoeuvres with low to medium speed steering input.

Stee
ring System - General Informatio
n - Power Steering System Filling
and Bleeding
Gen
eral Procedures
Fluid Level Indica

tor



1.
F
ill the reservoir to the bo
ttom of the filler neck.
W
ait for any air to escape and top up again.
W

ithout the engine running, tu
rn from lock to lock two or
three times, topping up to the maximum level on the dip
reservoir stick.
St
art the engine and
immediately top up as air is vented.
W
ith the engine idling, turn
lock to lock two or three
times, topping up to the ma ximum level on the reservoir
dip stick.
W
hen no further change of
fluid level occurs, run the
engine for twenty minutes to vent any remaining air.
If po
ssible, allow the vehicle
to stand for thirty minutes
before restarting the engine to vent any further air.
2. Note that air in the fluid can temporarily result in PAS pump
noise, but this will not cause damage. The time allowances
mentioned in the above procedures are to reduce the possibility
of a customer collecting a vehicle while still subject to
excessive pump noise.

Steering System - Gen
eral Informatio
n - Power Steering System Vacuum
Filling and Bleeding
Gen e
ral Procedures
Fluid Ho

ses



1.

Parts L i
st
It
e
m
De
scr
iption
1R
e
turn hose
2High
pressure h
ose
2. If vacuum filling equipment is available, proceed as follows:
Disconnect both the
high pres
sure hose and return hose
from the PAS pump and the re turn hose from the steering
rack.
D rain as much fl
uid as possible from the system by
turning the steering from lock to lock two or three times.
Re conn
ect all hoses.
Fi
ll
the system using the vacuum equipment according to
the manufacturers instructions.
St art
the engine and top up
the fluid as necessary.
Turn the steering from lock to lock two or three ti mes wi
th
the engine running, topping up with fluid as necessary.
If possibl
e, run the engine for twenty minutes to expel any

remaining air.

Power Steering -
Lubric
ants, Fluids, Sealants and Adhesives
Capacities
Torques


UnitSp
ecification
PAS flu
i
d
De
xr
on 3
UnitLi
t
ers
PAS syste
m1,0
PAS reservoi
r0,4
Com p
onent
Nm
Rac
k
mountin
g brac
ke
t to suspension crossbeam
40
- 50
PAS pump to front mounti
ng bracket
22
-
26
P
AS pu
mp assembly to cylinder block
38
-
48
Pul
l
ey to PAS pump
18
-
24
Hi
gh pressure hose to PAS pump22 -
28
Rack
pipe latch plate bolt8.5 -
11.5
R
e
servoir mounting bracket to body nuts
4 -

5
R
e
servoir mounting bracket clamp
4 -

5
Fluid cooler to body2.
5 -
3.5
Transfer pipe
to steering rack7 -
8
Transfer pipe
to hydraulic con
trol valve
7 -

8

The rotary distri
butor and control sleeve turn relative to ea
ch other, forming the unequal restrictions which create the
differential pressures to operat e the rack piston; the displacement of the di stributor and sleeve being controlled by the
elastic deformation of a torsion bar which is concentric with the pinion and valve. Refer to Positive Center-Feel Torsion Bar
in this sub-sectio n.
The hydraulic reaction piston moves axially, relative to th e rotary distributor, and is connected to the control sleeve by a
three-bearing helical screw. Pressure applied either side of the hydraulic reaction piston is translated into a rotational force
which increases steering effort. For detail s of Servotronic speed-sensitive steering control, refer to Servotronic Control in
this sub-section.
When the vehicle is travelling straight ah ead, the valve restrictions are balanced, thus providing equal pressures on either
side of the rack piston. When load is a pplied at the steering wheel, the two halves of the control valve (rotary distributor
and control sleeve) are displaced making the restrictions unequa l. The resulting differential pressures on either side of the
rack piston, assist the steering rack to mo ve to left or right. As the turning load is removed, the pressures equalize again
and the steering return s to the straight ahead position , aided by suspension geometry.
Serv
otronic Control

P a
rts List
The Servotronic system provides steering assistance which is pr oportional to vehicle speed. It comprises the steering control
module, and Servotronic valve forming part of the hydraulic control valve assembly.
The Servotronic valve is an electro-hydrauli c device with a variable orifice, which varies in size according to the position of a
needle valve. The needle valve is controlled by a solenoid in response to a variable current input from the steering control
Ite
m
Part
Number
Descr
iption
1—Vehi
cl
e speed input
2—Steeri
ng control
module
3—Servotronic valve
4—Hydraulic

control valve housing
5—PAS stee
rin
g pump
6—Batt
ery

Power Steering - Power Steering
Diagn
osis and Testing
Refer to the Description and Operation sub-section for details of the power operated steering system and Servotronic control
system.
Power Steer ing Pressure Test

Test Equ
i
pment

Parts List
In
stalling Test Equipment
To
in
stall the pressure test equipment:
Pla
c
e a suitable drain tray below the PAS pump.
Install a hose clamp
on
the re
servoir to pump hose prior to disconnecting any hoses, to avoid unnecessary loss of
fluid.
Di sc
onnect the hose from the PAS pump high pres
sure outlet.
Ins
tall the pump outlet to hose ad
aptor. Do not omit the O-ring.
Conn
ect the pump adaptor to control valve hose of the test equipment.
Install th
e adaptor in the high pressure hose previ
ously re
moved from the pump outlet.
Conne
ct the connector of the test equipment hose to the adaptor.
R
e
move the hose clamp fro
m the reservoir hose.
Start th
e engine.
With the control valve OPEN and the engine idling , the following system pressures may be checked:
Du
ring turning.
W
h
en the steering is
held on full lock.
With
the steeri
ng at rest.
• WARNINGS:
TO AVOID EXCESSIVE HEATING OF THE PAS PUMP, DO NOT CLOSE THE VALVE FOR LONGER THAN NECESSARY.
Ite
m
Par
t
Number
De
scr
iption
1—Pressure

gauge hose
2—Pump return hose
3—Pump return hose connector
4—Test equi
pment to
HP hose adaptor
5—Pump HP outlet to hose adaptor
6—Pump adaptor
to control valve hose
7—Control valve

DO NOT DRIVE THE VEHICLE WITH THE TEST EQUIPMENT INSTALLED.
With the control valve CLOSED the pump maximum output pressure can be checked.
Remov
ing Test Equipment
T
o remove the test equipment:
Install a hose clamp

on the
reservoir to pump hose.
Re
moving the test equipmen
t is a reversal of the installation instructions.
Install a new O-r
ing to the PAS pump high
pressure outlet to hose connection.
Inst
all the original hose to the PAS pump.
R

emove the clamp from the reservoir to pump hose.
Top-up the reservoi

r fluid.
B

leed the PAS system; refe
r to this section.
Refer to PDU
User Guide
T
he PDU will diagnose all electrical components of the system.
Before changing a component, chec k fuse No. 12 (10A) in the left-hand heelboard fu se box. However, if this fuse is faulty a
number of other components wi ll also fail to function.