GMC 4000 Series Service Manual page 506

NOTE: At regular intervals, the fluid level in
the reservoir should be checked and fluid added
when level is more than two inches below filler
cap. Refer to LUBRICATION (SEC. 0) of this man­
ual for type of fluid to be used.
IMPORTANT: Before checking fluid level,
start the engine and turn steering wheel to the left
and right several tim es to expel air from system ,
then shut off the engine.
PUMP REPLACEMENT
Removal
1. Loosen two cap screws which attach pump
mounting bracket to engine; then move pump in­
ward and remove drive belt.
2. Disconnect hoses at pump. When hoses are
disconnected, secure ends in raised position to
PUMP NOISE
The power steering pump is not completely
G M C S E R V I C E M A N U A L
Figure 7 — Slipper Type H yd ra u lic P u m p O p e ration
TROUBLESHOOTING THE HYDRAULIC PUMP
Rotor Slipper
1
Flow Control Valve
2
3 O-Ring Seal
4 Snap Ring
Control Valve Plug
5
Pump Body
6
7 Metering Insert
Control Valve Spring
8
9 Relief Valve Assembly
10
Rotor
Slipper Spring
11
Reservoir
12
prevent drainage of oil. Install caps at pump fit­
tings to prevent loss of fluid from pump.
3. Remove two cap screw s and lock washers
which attach pump and mounting bracket to engine.
Installation
1. Position pump and mounting bracket on en­
gine and attach with cap screw s and washers.
2. Install drive belt and adjust as previously
described under "Belt Tension."
3. Connect and tighten hose fittings.
4. Fill pump reservoir with fluid recommend­
ed in LUBRICATION (SEC. 0) of this manual.
5. Start engine and run for several minutes at
idle speed. Turn wheels from right to left several
tim es to expel all air from system. Recheck fluid
level in reservoir and fill to proper level.
noiseless. Some noise will be present whenever
the wheels are against the wheel stops. The noise
usually becomes greater as the engine speed is
Sec. 9B
Page 495
POWER STEERING
T-1799