Komatsu Utility PC12R-8 MISTRAL, Shop Manual

Page: 161 / 324

MEASUREMENT OF THE COMPRESSION PRESSURE
20-27
TESTING AND ADJUSTMENTS MEASUREMENT OF THE COMPRESSION PRESSURE
.
While measuring the compression, take care not
to get entangled in the cooling fan, the alternator
belt, or in other rotating parts.
.
Check all cylinders.
H Test conditions:
. Engine: at working temperature.
.
Hydraulic oil: 55 ± 60 ëC.
.
Battery: fully charged.
. Valve clearance: adjusted
(See «ADJUSTMENT OF VALVE CLEARANCE»).
.
Air filter functioning properly.
1 - Remove the clamp (1) and disconnect the high-pres-
sure tube (2).
2 - Remove the nozzle holder (3) of the cylinder to be
checked.
3 - Disconnect the connector (4) of the engine-stopping
solenoid.
4 - Turn the engine over a few times, using the starting
motor.
5 - Mount the adapter B2 and connect the test pressure
gauge B1 .
H Check that the seal is mounted in the adapter,
and that it is undamaged.
6 - Turn the engine using the starting motor and read the
compression value.
H Read the compression value when the pressure
gauge has stabilised.
H While reading the compression, also check the
engine rpm using the stroboscopic tachometer
C2 . If the speed does not correspond with the
control value, check it against the diagram.
H Compression value:
Normal: 33 w 1 kg/cm
2
at 250 rpm
Minimum permissible: 26 w 1 kg/cm
2
at 250 rpm
H Maximum difference between the cylinders:
2 ± 3 kg/cm
2
7 - After the reading, re-assemble the nozzle holder (3),
and reconnect the high- pressure tube (2) and the
connector (4).
Nut that secures the nozzle: 55 ± 59.5 Nm
High-pressure coupling: 33 ± 38.5 Nm
PC12R-8 PC15R-8
RKPA0020
1
2
3
RKPA0030
4
RKPA0040
B
1
B
2
RKP04781
35
40
30
25
20
200 250 300 350 400
Engine speed (rpm)
Compression (kg/cm
2
)