Bleeding The Power Steering System; Flushing The Power Steering System; Steering Gear High-Point Centering; Power Steering Gear Replacement - GMC G Service Manual

3B3-12 POWER STEERING
BLEEDING THE POWER
STEERING SYSTEM
When a power steering pump or gear has been removed
or an oil line has been disconnected, the air that has
entered the system must be bled out before the vehicle is
operated. If air is allowed to remain in the power steering
fluid system, noisy and unsatisfactory operation of the sys­
tem may result. Bleed air from the hydraulic system as
follows:
• When bleeding the system, and any time fluid is
added to the power steering system, be sure to use
only power steering fluid as specified in MAINTE­
NANCE AND LUBRICATION (SEC. OB).
1. Fill the pump fluid reservoir to the proper level and let
the fluid settle for at least two minutes.
2. Start the engine and let it run for a few seconds, then
turn the engine off.
3. Add fluid if necessary.
4. Repeat the above procedure until the fluid level
remains constant after running the engine.
5. Raise the front of the vehicle so the wheels are off the
ground.
6. Start the engine. Slowly turn the steering wheel right
and left, lightly contacting the wheel stops.
7. Check the fluid level and add fluid if necessary.
8. Lower the vehicle and turn the steering wheel slowly
from lock to lock.
9. Stop the engine. Check the fluid level and refill as
required.
10. If the fluid is extremely foamy, allow the vehicle to
stand a few minutes and repeat the above procedure.
VI
Inspect
• Belt for proper tension.
• Pulley for looseness or damage. The pulley should
not wobble with the engine running.
• Hoses so they are not touching any other parts of the
vehicle and are properly secured.
• Fluid level and fill to the proper level.
• Fluid for air. If present, bleed the system as described
above.
FLUSHING THE POWER
STEERING SYSTEM
1. Raise the front of the vehicle off the ground until the
wheels are free to turn.
2. Remove the fluid return line at the pump inlet connec­
tor and plug the connector port on the pump. Position
the line toward a large container to catch the draining
fluid.
3. While an assistant is filling the reservoir with new
power steering fluid, run the engine at idle. Turn the
steering wheel close to each stop. DO NOT contact
wheel stops or hold the wheel near a stop position or
fluid will stop and the pump will be in pressure relief
mode. A sudden overflow from the reservoir may
develop if the wheel is held at a stop.
4. Install all the lines, hoses and components (if
removed) on the vehicle. Fill the system with new
power steering fluid and bleed the system as
described in "Bleeding The Power Steering System"
in this section. Operate the engine for about 15 min­
utes. Remove the pump return line at the pump inlet
and plug the connection on the pump. While refilling
the reservoir, check the draining flu id for
contamination. If foreign material is still evident,
replace all lines and disassemble and clean or
replace the power steering system components. Do
not re-use any drained power steering fluid.
STEERING GEAR HIGH-POINT
CENTERING
1. Set the front wheels in the straight ahead position.
This can be checked by driving the vehicle a short
distance on a flat surface.
2. With the front wheels set straight ahead, check the
position of the mark on the wormshaft designating
steering gear high point. This mark should be at the
top side of the shaft at the 12 o'clock position and
lined up with the mark in the coupling lower clamp.
3. On R, G and P-Models except P30 with RPO FS3
I-beam front axle, if the steering gear has been
moved off high point when setting the wheel in the
straight ahead position, loosen the adjuster tube
clamps on both the left and right hand tie rods. Turn
both adjuster tubes an equal number of turns in the
same direction to bring the gear back on high point.
13
Important
• Turning the adjuster tubes an unequal number
of turns or in different directions will disturb the
toe setting of the wheels.
4. On V and P30 models with RPO FS3 I-beam front
axle, if the gear has been moved off high point when
setting the wheels in the straight ahead position,
loosen the adjuster tube clamps on the connecting
rod. Turn the adjuster tube to bring the gear back on
high point.
5. Check and adjust toe. Refer to FRONT END ALIGN­
MENT (SEC. 3A).
6. Refer to STEERING LINKAGE (SEC. 3B1) for
adjuster tube clamping instructions.
POWER STEERING GEAR
REPLACEMENT
Remove or Disconnect (Figures 8
through 13)
• Place a drain pan below the steering gear.
1. Negative battery cable.
2. Hoses from the steering gear. Raise the hose up to
prevent oil drainage. Cap or tape the ends of the hose
and gear fittings to prevent the entrance of dirt.