Komatsu PC88MR-10 Shop Manual page 954

40 Troubleshooting
Troubleshooting of hydraulic and mechanical system (H-
mode)
No. Cause
Defective adjustment of
7
LS valve
8 Malfunction of LS valve
Malfunction of servo
9
piston or PC valve (*)
Malfunction of piston
10
pump
40-466
Procedure, measuring location, criteria, and remarks
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
Lever position and oil pressure
Oil pressure to be
measured
Pump discharge Almost same as LS valve output
pressure
LS valve output Almost same as pump discharge
pressure
If normal oil pressure is not obtained after adjustment, check LS valve for
malfunction (fatigue of spring) and internal failure (stuck or seized LS spool).
Servo piston may malfunction. Check it.
If no failure is found by above checks, piston pump may have degraded
performance, malfunction, or have internal failure.
Check hydraulic tank strainer and return filter element for metal particles.
ratio
All levers in NEUTRAL
pressure
pressure
LS differential
pressure
Bucket CURL relief
Approx. 2.11 MPa
{21.5 kg/cm 2 }
PC88MR-10