Yanmar 2YM15 Service Manual download pdf (Page 130)

5. Inspection and servicing of basic engine parts

110R1

5.2.3 Intake/exhaust valves, valve guides

(1) Wearing and corrosion of valve stem

Replace the valve stem is excessively worn or

corroded.

(2) Inspection of valve seat wear and contact surface

Inspect for valve seat scratches and excessive wear. Check to make sure the contact surface is normal.

The seat angle must be checked and adjusted if the valve seat contact surface is much smaller than the

width of the valve seat.

NOTE:

Keep in mind the fact that the intake and discharge valve have different diameters.

(3) Valve sink

Over long periods of use and repeated lapping,

combustion efficiency may drop. Measure the sinking

distance and replace the valve and valve seat if the

valve sink exceeds the tolerance.

Valve stem

outside dia.

Standard Limit

Intake 5.960-5.975 5.90

Exhaust 5.945-5.960 5.90

Standard Limit

Valve sink 0.4-0.6 0.8

30 mm

Measurement point Measurement point

60 mm

(Valve sink depth)

Valve sinking depth

(Valve sink)

Depth micrometer

1 2 ... 125 126 127 128 129 130 131 132 133 134 135 ... 230 231

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Yanmar 2YM15 Service Manual Page 130