Yanmar 3YM30, Service Manual

Page: 132 / 231

5. Inspection and servicing of basic engine parts
112R1
4) Valve stem seals
The valve stem seals in the intake/exhaust valve
guides cannot be re-used. When they are
removed, be sure to replace them.
When assembling the intake/exhaust valves,
apply an adequate quantity of engine oil on the
valve stem before inserting them.
Exhaust stem seal is marked by yellow. Intake
stem seal is not marked.
a) Apply lube oil to the lip.
b) Push with the inserting tool for installation.
Measure and check the projection of valve stem seal to
keep proper clearance between valve guide and stem
seal.
5.2.4 Valve springs
(1) Checking valve springs
1) Check the spring for scratches or corrosion.
2) Measure the free length of the spring.
3) Measure inclination.
Valve stem seal projection (mm)
10.9-11.2
(Stem seal insertion)
Valve stem seal inserting tool
Stem seal
Valve guide
Cylinder head
001509-00E
Free length
(Valve spring)
001511-00E
(Valve spring)
Inclination
B
A
Square gauge