Workshop Manual
Rolls Royce Silver Shadow
8
Bentlev
T
Series
Chapter
N
flexible hose which sweeps downward and finally
Momentary aeration of the fluid is sometimes
curves upwards to join the pump inlet connection. The
noticeable under these conditions. Some noise may
rigid pipe is clipped to the wheel arch.
also
be
present under parking conditions.
Note
The correct run of hoses must
be
main-
tained in order to prevent kinking of the
flexible hoses thus restricting the flow of
steering fluid.
The worm-drive clips and pipe con-
nections must
be
correctly tightened to
prevent fluid leakage.
Metal-to-metal contact between rigid
and flexible pipes and the car body and
components must
be
avoided, except at
the clipping points, to prevent chafing,
rubbing and noise transference.
Steering Pump Test Data
Minimum output 1.46 Imp. gallons per minute (1.75
U.S.
gallons per minute, 6,64 litres
per minute) of fluid at
170°F.
(76.7"C.) when operating at 465
pump
r.p.m. against 665 lb/sq. in.
to
735 lb/sq. in. (46,75 kg/sq. cm.
to
51,68 kg/sq. cm.) pressure.
Maximum output
2.33 Imp. gallons per minute (2.80
U.S. gallons per minute, 10,68
litres per minute) of fluid at 170°F.
(76.7"C.) when operating at
1500
r.p.m.
against 50 Ib/sq. in. (3,52
kg./sq. cm.) pressure.
Maximum
sustained speed
I
5,800 r.p.m. (maximum peak speed
of pump
to
be
7,500 r.p.m.).
Pressure relief
Opens between
1100
lb/sq. in. (77,34
valve kg/sq. cm.) and
1200
lb/sq. in.
(84,37 kg/sq. cm.).
Fault Diagnosis
(For
quick
reference chart see Page
N49
and
onwards)
Pump
wise
The power steering pump is not completely noiseless.
Some noise may be present whenever the wheels are
on full lock. The noise usually becomes greater as
engine speed is increased as is the case when the car
is making a full lock turn. The noise is caused by the
system relief valve and is normal.
Power steering pump noise can
be
confused with
noises from other units of the
car.
To determine
whether excessive noise is present
in
the pump, start
the engine and increase the engine speed to
1000
r.p.m. A medium pitch 'moan' is emitted from the
pump which lowers in tone and increases
in
volume
as the steering column is loaded,
i.e. the road wheels
are turned toward lock; this is normal. The engine
r.p.m. decreases also as the road wheels are turned
from the straight ahead position. This is normal. As
the refrigeration compressor is driven from the same
belts, it will
be
necessary to determine whether or not
the noise is to
be
found in the compressor, this can
be
achieved by engaging and disengaging the com-
pressor clutch.
If it is determined that the excessive noise is present
in the steering pump, the following steps should be
taken in the order given.
1.
Check the driving belts for correct tensioning
2.
Check the fluid level, filling to the required level
if necessary.
3.
Check that the run of the hoses is correct.
4.
Check for presence of air in the fluid. Air will
show up as bubbles or, the fluid will appear frothy or
tan coloured. Small amounts of air can cause ex-
tremely noisy operation. If air is
present-
(i)
Check all fittings and bolts for tightness.
(ii)
Check the entire system for the source of the air
leak.
Air
can leak into the system at any place
but usually occurs at hoses or pipe connections
or, at the drive-shaft seal.
After each step in an attempt to eliminate air from
the system, the
pump should be operated at idle
speed while the road wheels are turned occasionally
from lock-to-lock.
5. If after step
(4)
there is no air present, insert a
pressure gauge in the high pressure line between the
steering pump and steering box. If, when increasing
the engine speed to
1000 r.p.m. with the front wheels
straight-ahead and without turning the steering wheel,
the fluid pressure exceeds 125
lb/sq. in. (8,79 kg/sq.
cm.)
it will be necessary to remove the pump from the
car then dismantle and inspect it as outlined under
'Pump-To inspect'.
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