Chevrolet 70 1969 Series, Shop Manual

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minutes, turn wheels to right and left as before.
D O N O T HIT T H E W H E E L STOPS. Recheck fluid
level. Recheck hoses and connections for leaks.
Continue this operation until fluid in reservoir is
clear.
5. Increase engine speed to approximately
1500 rpm and continue running at this speed until
all signs of air bubbles cease to appear in reser­
voir. Turn wheels (off the ground) to right and left.
D O N O T HIT T H E W H E E L STOPS.
6. Lower the vehicle and turn wheels on the
ground. Recheck for leaks.
7. Check fluid level in reservoir and refill.
HYDRAULIC PRESSURE TEST
VANE- TYPE H Y D R A U L IC PUMPS
1. Disconnect pressure hose from fitting at
the hydraulic pump. Connect a 0 to 2000 psi pres­
sure gauge (J-22181) between the pressure hose
and the pump pressure port. Leave valve in pres­
sure gauge line open (fig. 3).
2. Bleed steering hydraulic system to remove
all air from pressure line as directed previously
under "Bleeding Hydraulic System."
3. Start engine and run at idle speed. Turn
wheels through normal operating range several
times until the hydraulic fluid temperature reaches
170°F. When fluid temperature reaches 170°F.,
close valve in pressure gauge line and observe
reading on pressure gauge. Pressure reading should
Figure
4 — Checking
Pump Hydraulic Pressure
(Slipper Type Pump) (Typical)
be within 900-1000 psi on all pumps except model
235-P-47. On pump model 235-P-47, pressure
reading should be within 1100-1200 psi.
4. Open valve in pressure gauge line. Turn
wheels to extreme right and left against "stops"
(with wheels on ground). At extreme right or left
position the maximum pressure reading should be
within the amount specified in procedure 3 above.
SLIPPER T Y PE H Y D R A U L IC PUMP
1. Disconnect hydraulic pump to steering gear
pressure line at pump. Connect a 0 to 2000 psi
pressure gauge (J-22181) to the pump outlet; then
connect a shut-off valve between the pressure
gauge and pressure line (fig. 4). Make sure all
connections are tight and that shut-off valve is
fully open.
N O T E : The pressure gauge must be installed
between the pump and the shut-off valve.
2. Start the engine and run for several minutes
at idle speed. Turn wheels from right to left sev­
eral times to expel all air from system and to bring
fluid temperature to approximately 170°F.
3. Close shut-off valve and observe pressure
gauge. Pressure should be 1000 to 1100 psi.
N O T E : Do not close valve for more than a few
seconds, as this would increase fluid temperature
and cause excessive pump wear.
4. Open shut-off valve; then turn wheels to
extreme right and left with wheels on ground. At
extreme positions, the maximum pressure reading
should be within above limits.
5. If pressure is greater than 1100 psi or less
than 1000 psi, replace the pressure relief valve
and repeat the test. If pressure is still not within
limits specified, remove the pump and disassemble.
STEERING SYSTEM 9B-19
PUMP DRIVE BELT
M A IN T E N A N C E
The drive belt must be kept at proper tension.
A loose belt will reduce output of the hydraulic
pump, while a tight belt will cause eventual bear­
ing failure. A regular, periodic inspection is rec­
ommended to check condition of drive belt. Replace
belt if frayed or badly worn.
N O T E : On a new vehicle or after having in­
stalled a new drive belt, check belt tension twice
in first 200 miles of operation.
A D J U S T M E N T
1. Loosen hydraulic pump to mounting bracket
attaching bolts.
2. Position pump so that a reading of 120-130
pounds (new belt) or 90-100 pounds (used belt) is
obtained on a strand tension gauge.
3. Tighten pump to mounting bracket bolts.
CHEVROLET SERIES 70 -80 H EAVY DUTY TRUCK SH O P M A N U A L