Yanmar 3TNV82A-B, Руководство по обслуживанию

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ENGINE
6-44
TNV DI Service Manual
2-Valve Cylinder Head
Grind the valve face and / or valve seat only
enough to return them to serviceable condition.
Grinding is needed if the valve and the valve seat
do not contact correctly. Check the recession after
grinding.
If the valve or seat require grinding, lap the valve
after grinding. Lap the valve face to the valve seat
using a mixture of valve lapping compound and
engine oil.
Be sure to thoroughly wash all parts to remove all
grinding powder or compound.
Inspection of Valve Springs
Inspect the valve springs. If damage or corrosion is
seen, or if measurements exceed the specified
limits, replace the springs.
Fractures
Check for fractures on the inside and outside
portions of the springs. If the valve spring is
fractured, replace the valve spring.
Corrosion
Check for corrosion of the spring material caused
by oxidation.
Squareness
Use a flat surface and a square to check each
spring for squareness (Figure 6-26). See Valve
Spring on page 6-10 for the service limit.
Figure 6-26
Free Length
Use a caliper to measure the length of the spring
(Figure 6-27). See Valve Spring on page 6-10 for
the service limit.
Figure 6-27
Reassembly of Cylinder Head
Use new gaskets, O-rings and seals for the
reassembly of the cylinder head.
IMPORTANT
Liberally oil all components during
reassembly to prevent premature wear or
damage.
Reassembly of Valve Guides
1. The valve guides are installed into the cylinder
head with an extremely tight press fit. Before
installing the valve guides, place the valve
guides in a freezer for at least twenty minutes
This will cause the valve guides to contract,
making it easier to install the valve guides into
place.
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