Yanmar 3TNV Series Service Manual page 90

Point9
[Disassemble]
Carefully remove the fuel injection valve so as not
to leave the top end protector from being left
inside the cylinder.
[Reassemble]
Replace the fuel injection valve protector with a
new one.
Point10
[Disassemble]
When removing each intake/exhaust valve from
the cylinder head, use a valve spring compressor
(see 11.1-4 in Chapter 11) and compress the
valve spring and remove the valve cotter.)
Keep each removed intake/exhaust valve after
attaching a tag showing the corresponding
cylinder No.
If cotter burr is seen at the shaft of each
intake/exhaust valve stem, remove it with an
oilstone and extract the valve from the cylinder
head.
[Reassemble]
Replace the stem seal with a new one when an
intake/exhaust valve is disassembled.
Carefully install each valve after oil application so
as not to damage the stem seal.
Different stem seals are provided for the intake
and exhaust valves. Do not confuse them since
those for exhaust valves are marked with yellow
paint.
After assembling the intake/exhaust valve, stem
seal, valve spring, seat, and cotter, tap the head
of the valve stem lightly for settling.
Do not forget to install the valve cap.
4. Disassembly, Inspection and Reassembly of Engines
75