WÄRTSILÄ Vasa R22, Instruction Manual

Page: 151 / 297

Control of the burning off on valve
3 Check the sealing faces at the valves and the sealing
rings. For this purpose it is recommended to apply a thin layer
of fine lapping compound to the valve seat and rub the valve
slightly against the seat a few times by hand. If the sealing
faces are bright or if there is a coherent sealing face grinding
is not recommended. If there is slight pitting, only, lapping is
recommended. If the pitting extends over nearly the entire
sealing face or if imperfect sealing is observed the valve and
the seat should be reground.
Note! If blow-by has occurred, the O-ring for the corresponding valve
seat ring must be changed. Blow-by increases the temperature
and the O-ring is “burned”, which will result in water leakage into
the cylinder.
4 Before grinding, check the valve stem clearance. If the
clearance is too large, measure the stem and guide and change
the worn part; the valve guide can be pressed out. Check the
bore in the cylinder head. When refitting, cooling-in with liquid
air is recommended, but pressing in with oil lubrication can
also be accepted. After fitting in, check the guide bore and
calibrate, if necessary.
12.3.4 Lapping
If there are slight pits on the sealing faces they can be lapped by
hand:
1 Fit the turning tool to the valve.
Z
Y
Burn-off area
Fig 12-4
2212568932
22-9601 Cylinder Head with Valves 12
VASA 22 12 - 7