Yanmar 3YM30 Sevice Manual page 58

2. Inspection and adjustment
(5) Diaphragm assembly inspection
Inspect the diaphragm assy on the rocker arm cover.
1) Loosen screws,
assembly, 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]
1) When a diaphragm is damaged, pressure control
inside the crankcase becomes insufficient, and
troubles such as combustion defect and so on
occur.
2) At lube oil replacement or lube oil supply, the amount of lube oil isn't to be beyond the standard
upper limit. If the lube 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.
(6) Adjust the tension of the alternator driving belt
Replace the alternator driving belt with new one every 1000 hours or four years, whichever comes first,
even if there is no crack in the surface.
Refer to 2.2.2(4) for the procedure.
(7) Retighten all major nuts and bolts.
Retighten the major nuts and bolts bellow by the standard tightening torques. (See the table in 4.5.)
1) Cylinder head bolts
2) Crankshaft pulley bolts
3) Fuel injection nozzle set bolts
4) Fuel pump gear set bolts
5) Fuel injection line sleeve nut
Retighten the following major bolts as requested.
1) Rod bolts
2) Flywheel set bolts
3) Metal cap bolts
(8) Adjust intake/exhaust valve clearance.
Refer to 2.2.2(5) for the procedure.
(9) Check/adjust the remote control operation.
Refer to 2.2.2(6) for the procedure.
(10) Adjust the propeller shaft alignment.
1) The rubber tension of the flexible engine mounts is lost after many hours' use. This leads to a drop
in vibration absorption performance, and also causes centering misalignment of the propeller shaft.
(Refer to 5. "Flexible Engine Mount" in the installation manual for pleasure boat use.)
[Notice]
Be sure to replace the Yanmar flexible engine mounts every 1000 hours or 4 years, whichever comes
first.
2) After replacing the flexible engine mounts, check unusual noise and vibration of the engine and the
boat hull with increasing the engine speed gradually and lowering it.
3) If there is unusual noise and/or vibration, adjust the propeller shaft alignment. (Refer to 6.4.5
"Centering the Engine" in the installation manual for pleasure boat use.)
and remove a diaphragm
Diaphragm cover
Spring
Center plate
Diaphragm
Breather baffle
Baffle plate
(Breather system component)
43
Rocker arm cover
Intake manifold