Engine Speed Lowers Significantly Or Engine Stalls - Komatsu PC200-8M0 Shop Manual

500 Troubleshooting of hydraulic and mechanical system (H-mode)
H-2 Engine speed lowers significantly or engine stalls
H-2 Engine speed lowers significantly or engine stalls
q
Failure

Engine speed lowers significantly or engine stalls

Related infor-
q
Perform all troubleshooting with working mode in power mode (P).
mation
Defective adjustment or mal-
1
function of main relief valve
Malfunction of PC-EPC
2
valve
Probable
causes and cri-
teria
Defective adjustment or mal-
3
function of PC valve
Defective adjustment or mal-
4
function of LS valve
Clogging of orifice or filter in
5
serve device
6 Malfunction of servo piston
PC200, 200LC, 220, 220LC-8M0
Cause
a Be ready with engine stopped, then troubleshoot with engine
high idle.
Left work equipment control
If normal oil pressure is not obtained by adjustment, main relief
valve may malfunction or have internal defect. Check main relief
valve.
a Be ready with engine stopped, then troubleshoot with engine at
low speed and engine high idle.
a Be ready with engine stopped, then troubleshoot with engine
high idle.
Measured oil pres-
Pump discharge
PC valve output pres-
If normal oil pressure is not obtained after adjustment, PC valve
may malfunction or have internal defect. Check PC valve.
a Be ready with engine stopped, then troubleshoot with engine
high idle.
Measured oil pres-
Pump discharge
PC valve output pres-
If normal oil pressure is not obtained by adjustment, the LS valve
may malfunction or have internal defect. Check LS valve.
Orifices or filters in pump servo devices may be clogged. Check
them.
Servo piston may malfunction. Check it.
Criteria and troubleshooting procedure
lever
Arm IN relief
Engine Control lever
Low idle
All levers in the neu-
tral position
High idle
Measurement condi-
sure tions
Swing lock
pressure
Arm IN relief
sure
Operation of levers and oil pressure ratio
All levers in the neu-
sure
tral position
pressure Almost same pres-
sure
sure
SEN06139-00
Main relief pressure
33.3 to 37.2 MPa
{340 to 380 kg/cm
PC-EPC valve out-
put pressure
Approx. 2.9 MPa
{Approx. 30 kg/cm
0.52 to 0.91 MPa
{5.3 to 9.3 kg/cm
Ratio of oil pressures
1
Switch: ON
Approx. 0.6 (Approx.
3/5)
Run the track off
ground.
(lever at half stroke)
1
Approx. 0.6 (Approx.
3/5)
40-500
2
}
2
}
2
}
11