Chevrolet 1980 Light Duty Truck Service Manual page 201

CONDITION
SYSTEM NOISE
There is some noise in all power
steering systems.
Common complaints are listed as
follows:
Pump noise-"chirp" .
Belt squeal.
Gear noise ( "hissing" sound)
Rattle.
Gear noise (rattle or chuckle).
Rattle or chuckle.
Groan.
Groan.
Growl.
POSSIBLE CAUSE
Loose belt.
Loose belt.
There is some noise in all power steer­
ing systems. One of the most common
is a hissing sound most evident at
standstill parking. There is no relation­
ship between this noise and perfor­
mance of the steering. " Hiss" may be
expected when steering wheel is at end
of travel or when slowly turning at
standstill.
Pressure hose touching other parts of
car.
Loose pump pulley nut
Pump vanes not installed properly.
Pump vanes sticking in rotor slots.
Improper over-center adjustment
NOTE: A slight rattle may occur on
turns because of increased clearance
off the " high point" . This is normal
and clearance must not be reduced
below specified limits to eliminate this
slight rattle.
Loose pitman arm.
Gear loose on frame.
Steering linkage looseness.
Low oil level.
Air in the oil. Poor pressure hose
connection.
Excessive back pressure caused by
hoses or steering gear, (restriction)
Fig. 3 B 3 -2 -P o w e r Steering System Diagnosis C hart A
POWER STEERING SYSTEM
CORRECTION
Adjust belt tension to specification.
Adjust belt tension to specification.
Do not replace valve unless " hiss" is
extremely objectionable. Slight " hiss"
is normal and in no way affects steer­
ing. A replacement valve will also exhi­
bit slight noise and is not always a cure
for the objection. Investigate clearance
around flexible coupling rivets. Be
sure steering shaft arid gear are aligned
so flexible coupling rotates in a Hat
plane and is not distorted as shaft ro­
tates. Any metal-to-metal contacts
through flexible coupling will transmit
"hiss" into passenger compartment.
Also, check for proper sealing betw een
steering colum n and toe pan.
Adjust hose position.
Replace nut, torque to specs.
Install properly.
Free up by removing burrs, varnish or
dirt.
Adjust to specifications.
Tighten to specifications
Check gear-to-frame mounting bolts.
Tighten bolts to 70 foot-pounds.
Check linkage pivot points for wear.
Replace if necessary.
Fill reservoir to proper level.
Bleed system by operating steering
from right to left full turn.
Check connections, torque to specs.
Locate restriction and correct. Replace
part if necessary.
3B3-3
L IG H T T R U C K SER V IC E M ANUAL