Hydraulic System Flushing Procedure - Komatsu 930E-2 Shop Manual

HYDRAULIC SYSTEM FLUSHING PROCEDURE

The following instructions outline the procedure for
flushing the hydraulic system.
Preparation
1. Verify and correct if necessary, the various relief
valves and adjustable hydraulic system compo-
nents. (Refer to "Hydraulic Checkout proce-
dure".)
2. Place selector switch in NEUTRAL, apply the
parking brake and place the Rest switch in the
ON position. (Leave Rest switch ON for all the
following procedures.)
a. Shut down engine and turn key switch OFF. Be
certain the Link Voltage warning lamps
turn off.
b. Allow at least 90 seconds for the steering
accumulators to bleed down.
c. Open the brake accumulator bleed down
valves on the brake manifold.
(This will return contaminants in the brake
accumulators to the hydraulic tank.)
3. Thoroughly clean the exterior of the hydraulic
tank. Drain the hydraulic tank and flush the inte-
rior with a cleaning solvent. Inspect all hydraulic
hoses for deterioration or damage.
NOTE: If a system component fails, all flexible hoses
should be removed and back flushed with a cleaning
solvent. Inspect for small particles which may be
trapped inside the hose.
4. Remove, clean and reinstall the hydraulic tank
strainers. Change all high pressure filter ele-
ments.
5. Fill hydraulic tank with clean, Type C-4 hydraulic
oil.
6. Be certain suction line shut-off valves are open.
7. Bleed trapped air inside steering pump. (Refer to
"Steering and Brake Pump", Section L.)
L10-10
Flushing Procedure
1. Set all controls in the "Neutral" position. Do not
steer the truck or operate controls until the next
step is completed.
2. Start the engine and run at 1000 RPM for five
minutes. This will circulate oil with all valves in
the neutral position.
3. To increase flow and turbulence in the system,
increase engine speed to full throttle and main-
tain for four minutes. This will carry contaminates
to the hydraulic tank.
4. Shut down engine and turn key switch OFF. Allow
at least 90 seconds for the accumulators to bleed
down.
5. Close the brake accumulator bleed down valves
on the brake manifold (opened in step 2.c.,
"Preparation")
6. To enable full extension of the hoist cylinders,
disconnect hoist limit solenoid on bottom of
bleeddown manifold.
7. Start engine and run at 1000 RPM while perform-
ing the following:
a. Steer truck full left then full right - repeat ten
b. Steer full left (keeping pressure against the
c. Steer full right (keeping pressure against the
NOTE: Hydraulic tank oil temperature should be 110°
- 130°F (43° - 54°C) after accomplishing Step 6.
If not, repeat Step 3 to increase oil temperature
to the proper operating range.
8. Increase engine speed to full throttle and steer
full left and full right.
9. Return all controls to "Neutral".
Hydraulic Check-out Procedure
(10) times.
steering wheel) and hold for 10 seconds.
steering wheel) and hold for 10 seconds.
L10012