Yanmar 4JH4E - Page 205

5. Inspection and servicing of basic engine parts
185
(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.
(4) Valve guide
1) Measuring inside diameter of valve guide.
Measure the inside diameter of the valve
guide and replace it if it exceeds the wear
limit.
Note:
The inside diameter standard dimensions
assume a pressure fit.
2) Replacing the valve guide
a) Use a valve guide extraction tool and
extract the valve guide from the cylinder
head.
mm
Standard Limit
Valve sink 0.30-0.50 0.8
mm
Standard Limit
3JH4E
4JH4E
Valve guide
inside diameter
Intake 8.010-8.025 8.2
Exhaust 8.015-8.030 8.2
Clearance
Intake 0.035-0.070 0.18
Exhaust 0.045-0.075 0.18
4JH4-TE
4JH4-HTE
Valve guide
inside diameter
Intake 6.000-6.015 6.1
Exhaust 6.000-6.015 6.1
Clearance
Intake 0.025-0.055 0.16
Exhaust 0.040-0.070 0.18
Sink
Cylinder head
006550-00E
Depth micrometer
010696-00E