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To Bleed Air From Pump:
a. With the engine OFF and the hydraulic oil
level in the tank is at the proper level, open
shut-off valve in steering pump suction line.
b. With suction line shut-off valve open, loosen
suction hose cap screws (at the pump) to
bleed any trapped air. Then loosen pressure
hose cap screws (at the pump) to bleed any
trapped air. Tighten hose connection cap
screws to standard torque.
NOTE: If trapped air is not bled from steering pump,
possible pump damage and no output may result.
c. Disconnect pump case drain hose (from fit-
ting 2, Figure 10-1) and cap the hose.
d. Remove fitting (2) and add clean C-4 type oil
to pump through opening until pump housing
is completely full.
e. When pump housing is full of oil, install fitting
(2) and connect pump case return hose to fit-
ting.
6. Check hydraulic oil in tank is visible in upper
sight gauge. Add oil if necessary.
NOTE: Allow adequate time for the accumulator to
fully charge after start up.
7. Start engine and run at low idle. The steering
pump with unloader valve is preset to unload
the pump at 24 133 to 24 477 kPa (3500 to
3550 psi), and reload accumulators when their
pressure falls to 2,2064 ± 345 kPa (3200 ± 50
psi). If necessary to adjust pump pressure:
a. Install calibrated pressure gage capable of
35 000 kPa (5000 psi) at base of either steer-
ing accumulator in the SAE #4 (or #6) port or
on a tee placed in the port marked "ACC" on
the unloader valve block on the pump.
L10-4
b. Bottom out the unloader valve adjustment
c. Back out the pressure compensator adjust-
d. Fully open all shut-off valves.
e. Start truck and adjust pressure compensator
f. Shut down the engine and allow sufficient
g. Back out unloader valve adjustment screw
h. Start truck and allow pump to unload:
i. Adjust unloader valve:
j. Steer to cause accumulator pressure to
Note: The critical pressure adjustment is the
unloader valve reload pressure. The pressure at
which it unloads is not adjustable separately but will
follow the reload pressure adjustment.
Hydraulic Check-out Procedure
screw (11, Figure 10-1).
ment screw (8).
(8) until 26 200 kPa (3800 psi) is read and
maintained on gauge at steering pump
"GPA" test port (5). Tighten jam nut (7).
time for the accumulators to bleed down
(11) completely.
Pressure gauge at steering pump "GPA"
test port will read about 1 379 to 2 758 kPa
(200 to 400 psi) when the pump is
unloaded.
Adjust to reload pump when pressure drops
to 2,2064 ± 345 kPa (3200 ± 50 psi).
decrease enough so accumulators are
reloaded to verify unloader valve setting:
The pressure gauge in the port marked
"ACC" should read 2,2064 ± 345 kPa (3200
± 50 psi). Tighten jam nut.
L10028
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