Diagnosis Of Power Steering System - GMC G Service Manual

DIAGNOSIS OF POWER STEERING SYSTEM

PROBLEM
Objectionable "Hiss" 1. Noisy relief valve in the hydraulic pump.
2. Any metal-to-metal contacts through flexible
Rattle Or Chuckle 1. Gear loose on the frame.
Noise In Steering
Gear 2. Steering linkage looseness.
3. Pressure hose touching other parts of
4. Loose pitman arm.
5. Improper over-center adjustment. A slight
1. Air in the system.
Excessive Wheel
Kick-Back Or Loose
Steering
2. Steering gear mounting loose.
3. Steering linkage joints worn.
4. Front wheel bearings incorrectly adjusted or
5. Steering gear improperly adjusted.
6. Worn or missing poppet valve (steering
7. Steering gear flexible coupling too loose on
8. Damaged or worn steering gear.
Vehicle Leads To One 1. Front end misaligned.
Side Or The Other 2. Unbalanced steering gear valve. If this is
(Keep In Mind The
Road And Wind
Conditions). Test The
Vehicle, Going In 3. Steering shaft rubbing the ID of the shaft
Both Directions, On A
Rat Road. 4. Steering linkage not level.
Momentary Increase 1. Low oil level in the pump.
In Effort When 2. Pump belt slipping (if used).
lUmlng The Wheel 3. High internal linkage (steering gear or
Quickly To the Right
Or Left
POSSIBLE CAUSE
coupling.
vehicle.
rattle may occur on turns because of in­
creased clearance off the "high point." This is
normal and clearance must not be reduced
below specified limits to eliminate this slight
rattle.
worn.
gear).
the shaft or the rubber disc mounting screws
loose.
cause, steering effort will be very light in di­
rection of lead and heavy in opposite
direction.
tube.
pump).
POWER STEERING 3B3-5
CORRECTION
1. There is some noise in all power steering
systems. One of the most common is a hiss­
ing sound most evident at standstill parking.
Hiss is a high frequency noise. The noise is
present in every valve and results from high
velocity fluid passing valve orifice edges.
There is no relationship between this noise
and performance of the steering. "Hiss" may
be expected when steering wheel is at end of
travel or when slowly turning at standstill.
Do not replace valve unless "hiss" is ex­
tremely objectionable. A replacement valve
will also exhibit slight noise and is not always
a cure for the objection.
2. Align the steering shaft and gear so the flexi­
ble coupling rotates in a flat plane and is not
distorted as the shaft rotates.
1. Check the gear mounting bolts. Torque the
bolts to specifications.
2. Check linkage pivot points for wear. Replace
if necessary.
3. Adjust the hose position. Do not bend tubing
by hand.
4. Torque the pitman arm bolt.
5. Adjust to specifications.
1. Add oil to the pump reservoir and bleed.
Check hose connectors for proper torque.
2. Tighten attaching bolts to specified torque.
3. Replace loose parts.
4. Adjust the bearings or replace with new parts
as necessary.
5. Adjust to specifications.
6. Replace the poppet valve.
7. Tighten to specifications.
8. Disassemble and repair the steering gear as
outlined in the unit repair manual.
1. Adjust to specifications.
2. Replace the gear valve.
3. Align the column.
4. Adjust as required.
1. Add power steering fluid as required.
2. Tighten or replace belt.
3. Refer to "Power Steering System Test" in this
section.
GMTB-0868-2L