H-2 Engine Speed Drops Significantly Or Engine Stalls - Komatsu PC88MR-10 Shop Manual

H-2 Engine speed drops significantly or engine stalls

Engine speed drops significantly or engine stalls.
Failure
Perform all troubleshooting with working mode set in power (P) mode.
If any failure code is displayed, perform troubleshooting for that failure code first.
Related
(DXA8KA or DXA8KB)
information
Pump pressure can be checked with monitoring function. (monitoring code: 01100)
No. Cause
Malfunction of main
1
relief valve
Malfunction of main
2
relief valve
Malfunction of PC-EPC
3
valve
Defective adjustment of
4
PC valve
5 Malfunction of PC valve
Defective adjustment of
6
LS valve
7 Malfunction of LS valve
Clogging of orifice or
8
filter in serve device
Malfunction of servo
9
piston
PC88MR-10
Troubleshooting of hydraulic and mechanical system (H-
Procedure, measuring location, criteria, and remarks
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
Main relief pressure
When pressure cannot be adjusted to normal level, check main relief valve for
malfunction (fatigue of spring) and internal defect (defective valve seat).
a Be ready with engine stopped, then perform troubleshooting with engine
running at low idle and at high idle.
Engine at low idle and all levers in
PC-EPC valve
output pressure
Engine at high idle and all levers
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
Oil pressure to be
measured
Pump discharge
pressure
PC valve output
pressure
When pressure cannot be adjusted to normal level, check PC valve for
malfunction (fatigue of spring) or internal defect (stuck or seized PC spool).
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
pressure
LS valve output
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).
Check orifices and filters in pump servo devices for clogging.
If no failure is found by above checks, piston pump may malfunction or have
internal defect.
Check hydraulic tank strainer and return filter element for metal particles.
Arm IN hydraulic relief
NEUTRAL
in NEUTRAL
Measurement condition
Arm IN hydraulic relief
Arm IN hydraulic relief
ratio
All levers in NEUTRAL
Pump discharge pressure is
almost same as LS valve
pressure.
Pump discharge pressure is
almost same as LS valve
pressure.
40 Troubleshooting
mode)
(PC88MR-FPN-400-A-Z0-A)
26.5 ± 1.5 MPa
{270 ± 15 kg/cm
1.72 to 2.60 MPa
{17.5 to 26.5 kg/cm
0.69 to 1.42 MPa
{7.0 to 14.5 kg/cm
Oil pressure ratio
1
Approx. 0.2 to 0.6
LS differential
pressure
Bucket CURL relief
Approx. 2.11 MPa
{21.5 kg/cm 2 }
40-467
2 }
2 }
2 }