Fluid Leak Check; Power Steering System Test - GMC G Service Manual

3B3-8 POWER STEERING

FLUID LEAK CHECK

1. With the engine off, wipe the complete power steering
system dry (gear, pump, hoses and connections).
2. Check the fluid level in the pump reservoir and adjust
as directed in "Fluid Level Adjustment" in this section.
3. Start the engine and turn the steering wheel from stop
to stop several times. Do not hold the wheel against
the stops as this may damage the pump.
4. Find the exact areas of leakage and use the recom­
mended method of repair as shown in figure 5.

POWER STEERING SYSTEM TEST

The power steering system may be tested using either
J 5176-D Power Steering Gage or with J 25323 Power
Steering Analyzer. J 25323 will measure the flow rate in
addition to the pressure (figure 6).
The power steering system test is used to identify and
isolate hydraulic circuit difficulties. Prior to performing this
test, the following inspection and corrections (if necessary)
must be made.
IC T Inspect
Pump reservoir for proper fluid level.
Pump belt for proper tension.
Tires for correct air pressure.
Power steering system, replacing parts as necessary.
I { | Important
• All tests are made with the engine idling at normal
operating temperature. Check the idle speed adjust­
ment and, if necessary, adjust to the correct specifi­
cation. Refer to CARBURETORS (SEC. 6C1) and the
Fuel, Driveability and Emissions Service Manual.
TEST WITH J 5176-D
1. Place a container under the steering gear or pump to
catch the fluid when disconnecting or connecting the
hoses.
2. With the engine OFF, disconnect the pressure hose
at the steering gear or power steering pump and
install J 5176-D to both hoses using adapter fitting
J 5176-20. The gage must be between the shutoff
valve and pump. Open the shutoff valve.
3. Remove the filler cap from the pump reservoir and
check the fluid level. Fill the pump reservoir with
power steering fluid to the full mark on the dipstick.
Start the engine and, momentarily holding the steer­
ing wheel against the stop, check the connections at
J 5176-D for leakage.
I ! \ Important
• Do not hold the wheel against the stop for more
than 5 seconds as the pump can be damaged
internally.
4. Bleed the system. Refer to "Bleeding the Power
Steering System" in this section.
5. Insert thermometer J 5421-02 in the reservoir filler
opening. Move the steering wheel from stop to stop
several times until the thermometer indicates that the
hydraulic fluid in the reservoir has reached a temper­
ature of 65 to 77 degrees C (150 to 170 degrees F).
] Important
• To prevent scrubbing flat spots on the tires, do
not turn the steering wheel more than five times
without rolling the vehicle to change the tire-to-
floor contact area.
6. Check the pump fluid level. Add power steering fluid if
required. When the engine is at normal operating
temperature, the initial pressure on the gage (valve
open) should be in the 550-860 kPa (80-125 psi)
range. If the pressure is in excess of 1380 kPa (200
psi), check the hoses for restrictions and the poppet
valve for proper assembly.
NOTICE: Do not leave valve fully closed for more
than 5 seconds as the pump could be damaged
Internally.
7. Open and close the gage valve fully 3 times. Record
the highest pressures attained each time.
• If the pressures recorded are within the specifi­
cations at the end of this section, and the range
of readings is within 345 kPa (50 psi), the pump
is functioning within specifications.
• If the pressures recorded are high, but do not
repeat within 345 kPa (50 psi), the flow control
valve is sticking. Remove the valve, clean it,
and remove any burrs using crocus cloth or a
fine hone. If the system contains some dirt,
flush it. If it is exceptionally dirty, both the pump
and gear must be completely disassembled,
cleaned, flushed and reassembled before fur­
ther use.
• If the pressures recorded are constant but more
than 690 kPa (100 psi) below the minimum
listed specification, replace the flow control
valve and recheck. If the pressures are still low,
replace the rotating group in the pump.
8. If the pump checks within specifications, leave the
valve open and turn the steering wheel to both stops.
Record the highest pressures and compare with the
maximum pump pressure recorded. If this pressure
cannot be built in either (or one) side of the gear, the
gear is leaking internally and must be disassembled
and repaired.
9. Turn the engine off, remove the testing gage, recon­
nect the pressure hose, check the fluid level and/or
make the needed repairs.
10. If the problem still exists, the steering and front sus­
pension must be thoroughly examined. Refer to
"Diagnosis of Power Steering System" in this section.