Yanmar 3TNV Series Service Manual page 53

2. Inspection and Adjustment
(2) Diaphragm assy inspection
Inspect the diaphragm assy on the rocker arm cover
every 1000 hours or 2 years. Refer to 4.2.4 point 6
for the function of the diaphragm.
1) Loosen screws, and remove a diaphragm assy,
and check whether oil and so on doesn't enter
between the diaphragm and the cover. If oil and
so on enters into the diaphragm assy, the
diaphragm doesn't work well.
2) Check the damages of the diaphragm rubber and
the spring. If necessary, replace with new ones.
[NOTICE]
When a diaphragm is damaged, pressure control
inside the crankcase becomes insufficient, and
troubles such as combustion defect and so on
occur.
At lubricating oil replacement or lubricating oil
supply, the amount of lubricating oil isn't to be
beyond the standard upper limit. If the lubricating
oil quantity is beyond the upper limit or an engine
is operated beyond the allowable maximum angle
of an engine, the amount of oil mist may be
inducted in the combustion chamber and the oil
hammer sometimes may occur.
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