Yanmar 3JH4E Service Manual page 52

2. Inspection and Adjustment
4) Pressure cap inspection
a) Remove scale and rust and check the seat and seat valve, etc. for scratches or wear. Check the
spring for corrosion or settling. Replace if necessary.
[NOTE]
Clean the pressure cap with fresh water as it will not close completely if it is dirty.
b) Fit the adopter on the tester to the pressure cap.
Pump until the pressure gauge is within the
specified pressure range 0.074-0.103MPa (0.75-
2
1.05kgf/cm ) and note the gauge reading. The
cap is normal if the pressure holds for six
seconds. If the pressure does not rise, or drop
immediately, inspect the cap and repair or
replace as necessary.
(5) Diaphragm assembly inspection
Inspect the diaphragm assy on the rocker arm cover.
1) Loosen screws, remove the diaphragm assembly,
and check for oil and contaminants between the
diaphragm and the cover. If oil and contaminants
enter into the diaphragm assembly, the diaphragm
will not operate as designed.
2) Inspect the diaphragm rubber and spring for
damage. 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 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.
(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.
Do not open the pressure cap while the engine is running or right after
stopping because high temperature steam will be blown out. Remove the
cap only after the water cools down.
36
Spring
Center plate
Diaphragm
Breather pipe
Intake silencer
(Breather system component)
Diaphragm cover
Rocker arm cover
Breather
baffle
Baffle plate