GMC 4000 Series Service Manual page 510

cylinder housing, until it bottoms. Using a grease
pencil or other suitable marking device, place
mark on piston rod at cylinder housing.
4. Loosely attach cylinder tie rod bracket, to
tie rod so that it is free to slide on rod.
5. Extend power cylinder piston rod out of
cylinder housing to its full length of travel (bot­
tomed) and mark piston rod.
6. Depress piston rod 1 /8 -inch and tighten to
tie rod. It is most important the piston rod be de­
pressed 1/8-inch from the fully extended position
while the piston rod is secured to the tie rod.
NOTE: For proper torque on power steering
POWER CYLINDER LEAKAGE
INTERNAL LEAKS
Internal leakage in the power cylinder will
show up in a momentary increase in driver effort
when turning the wheel fast. If this occurs, replace
complete cylinder assembly.
EXTERNAL LEAKS
If the power cylinder is leaking externally,
wipe it clean to determine where it is leaking.
Leakage around the piston rod seals may be cor­
rected by replacing the seals. If the power cylin­
der still leaks after replacing the seals, the p res­
sure relief valve is not operating properly and the
complete power cylinder will have to be replaced.
An oil cooler is attached to the radiator front
support on all vehicles with power steering except
with air conditioning.
The oil cooler may be removed for repair or
replacement by disconnecting hoses and removing
screw s which attach it to support braces.
OIL COOLER MAINTENANCE
At regular intervals, or when operating con­
ditions warrant, examine the cooler for leaks and
bent fins. A damaged or leaking cooler should be
serviced by a radiator specialist or replaced with
a new assem bly. Proper repair requires the use of
G M C S E R V I C E M A N U A L
TROUBLESHOOTING
OIL COOLER
components, refer to "Power Steering Specifica­
tions" later.
7. Position wheels in a full left-hand turn,
against wheel stop.
8. Check that first marking on piston rod (pis­
ton rod depressed) is still visible.
NOTE: Proper adjustment of power cylinder
is achieved when cycled from a full left-hand to
right-hand turn without the cylinder bottoming.
9. Check for clearance of cylinder at both
axle and tie rod while wheels are being turned.
Repeat adjustment procedure, if necessary.
THE POWER CYLINDER
Any leakage around the welds on the cylinder will
necessitate replacing the complete power cylinder
assembly. Tighten the hose connections at the ex­
tension and retraction ports if this is a source of
leakage. If tightening the connection does not stop
leakage, replace complete cylinder assembly.
NOTE: Any damage to the cylinder which will
hamper its operation necessitates replacement of
the complete power cylinder assembly. The cylin­
der is not serviced except for the piston rod seals.
NOTE: For additional troubleshooting inform­
ation, refer to "Quick Reference Troubleshooting
Chart" at end of this section.
special tools and equipment as well as provisions
for making proper tests.
If the cooler assembly requires painting, spray
with special radiator paint; do not use paint mixed
with oil, as oil mixed paint will form an insulation
and prevent efficient dissipation of heat.
Occasional external flushing with water, using
an ordinary hose, will help remove dirt, bugs and
other foreign matter from between fins of cooler.
Water under pressure should be directed from be­
hind the cooler to force dirt out in opposite direc­
tion of its entrance. Direct the water stream against
edges of fins (not sideways) to eliminate danger of
bending fins.
Sec. 9B
Page 499
POWER STEERING