Man D 2866 LE 401, Repair Manual

Page: 97 / 138

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Refacing valves
96
Fig. 1
Apply abrasive paste to tapered area on the valve
seat.
Oil valve guide and insert valve.
Fig. 2
Use valve refacer to reface valve seat by applying
moderate axial pressure and describing a turning
motion.
Important:
Keep valve stem and valve guide free of
abrasive paste.
Fig. 3
The valve seat must have a faultless, closed grind-
ing pattern (2).
The grinding pattern width is correct if the valve
seat insert is in order.
1 Valve tapered area
2 Valve seat
Fig. 4
1 Valve seat insert
2 Valve
3 Valve seat good
4 Valve seat too wide
Note:
Valve seats which are too wide tend to accu-
mulate coking residues,
– valves become leaky –
Valve seats that are too small prevent rapid
discharge of heat from the valve disc to the
cylinder head,
– valves burn –
3535
3591
2821
1 2
2822
1 2 1 2
4 3