Group
21
Reconditioning engine
Cylinder head, reconditioning
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Valve seat replacement
Operations
El5-22
Note!
Valve guides must always be renewed before repla-
cing seats, see E8-14.
E15
Clean combustion chambers
Clean the surfaces until the edge of the inserted seat is
clearly visible.
E16
Remove valve seat
Machine the valve seat. Use Mira valve cutter P/N
998 6045-5. Follow the manufacturer's instructions.
Make sure that the cylinder head is not damaged. Clean
carefully.
E17
Measure valve seat diameter in cylinder head and
select a new seat of correct size
Use an internal micrometer.
Valve seats are available in three oversizes.
The interference between the valve seat and recess in
the cylinder head must be
0.070-0.134
mm
(0.0027-0.0052 in).
I.
e. the valve seat must be
0.070-0.134
mm larger than the recess in the cylinder
head.
If too small, fit
a
new cylinder head. If too large, mill the
valve seat to correct size. Use a valve cutter.
E18
Heat up cylinder head
Approx.
100°C.
(212°F).
49
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