Adjustment Of Valve Clearance - Komatsu PC20R-8 Shop Manual

TESTING AND ADJUSTMENTS

ADJUSTMENT OF VALVE CLEARANCE

Adjust the clearance between valve and rockers to the
.
following values:
Suction valves
With
engine
cold
0.20
1 - Remove the intake filter and the valve cover.
2 - Turn the drive shaft in the normal direction of rotation
until the line (1) marked as no. 1 on the flywheel is in
alignment with the reference notch (2) on the flywheel
housing.
H If the cylinder is in a compression stroke, the
valves do not move when the drive shaft is rotated
slightly.
If the valves do move, rotate the drive shaft by one
turn and realign the reference marks (1) and (2).
3 - Loosen the lock nut (3) and unscrew the adjustment
screw (4) by approximately 1 turn.
H Check that the valve cap (5) is lying flat on the
valve stem and that there is no lop-sided wear.
1 - If the valve caps (5) are damaged, replace
them with new ones.
2 - Make sure that the valve caps fit perfectly and
are lying flat on the valve stem.
4 - Insert the feeler gauge A1 between the rocker (6) and
the valve cap (5).
Rotate the adjusting screw (4) until it rubs against the
feeler gauge A1.
Secure this position with the nut (3).
Lock nut: 25.5w2.5 Nm
H After locking the nut (3), check the valve clear-
ance again.
5 - After adjusting the N
shaft 240ë each time and adjust the valve clearance
of the other cylinders according to the ignition se-
quence.
H Ignition sequence: 1 - 3 - 2.
Assembly of the valve cover
.
1 - Check the condition of the gasket (7) of the valve
cover (8), and the O-rings (9). Thoroughly clean
the contact surface on the cylinder heads.
2 - Replace the valve cover (8) and mount the O-rings
(9) and the lock nuts (10).
Lock nuts for cover: 25w3 Nm
20-26
Unit: mm
Exhaust valves
0.20
. 1 cylinder, rotate the drive
o
ADJUSTMENT OF VALVE CLEARANCE
1
5
RKP06450
4
6
A1
10
9
7
2
RKP06440
4
3
NO
YES
NO
SI
5
3
RKP06530
8
RKP06560
PC20R-8 PC27R-8