Measuring Blow-By Pressure - Komatsu WA250-6 Shop Manual

110 Testing and adjusting, Part 1

Measuring blow-by pressure

Measuring blow-by pressure

a Necessary tools
Symbol Part No.
D 799-201-1504 Blow-by checker
a Measure the blow-by pressure under the fol-
lowing condition.
Engine coolant temperature:
q
Hydraulic oil temperature:
q
HST oil temperature:
q
1. Stop the engine. Install nozzle [1] and hose [2]
of blow-by checker D to blow-by hose (1) and
connect them to gauge [3].
a Blow-by hose (1) comes out from the rear
left of the engine and its end is fixed to the
machine lower frame.
2. Start the engine and increase the engine cool-
ant temperature to the operating range.
3. Press the left brake pedal securely.
4. Release the parking brake.
WA250, 250PZ-6
1
Part Name
Within operating range
Within operating range
Within operating range
5. While pressing the brake pedal, set the direc-
tional lever or switch to the F (forward) or R
(reverse) position.
k
Keep pressing the brake pedal securely.
6. Press the accelerator pedal gradually to the
high idle. While running the engine at HST
stalling and hydraulic stalling, and measure the
blow-by pressure.
a Do not keep stalling the HST for more
than 20 seconds. Take care that the HST
oil temperature will not exceed 120°C.
a Normally, the blow-by pressure should be
measured while the engine is operated at
the rated output. In the field, however, an
approximate value can be obtained by
HST stalling and hydraulic stalling.
a If it is impossible to run the engine at the
rated output or HST stalling and hydraulic
stalling, measure while the engine is run-
ning at high idle. The value obtained in
this case is about 80% of the blow-by
pressure at the rated output.
a Precaution for measuring blow-by pressure
The blow-by pressure may vary largely
with the engine condition. If the measured
value is judged abnormal, check for
increase of oil consumption, bad exhaust
gas color, deterioration of oil, high deterio-
ration speed of oil, etc. which are related
to the abnormal blow-by pressure.
7. Remove the measurement tool after the mea-
surement, and make sure that the machine is
back to normal condition.
SEN03836-01
19
30-110