Refacing Valve Seats With Hand Cutter - Mercedes-Benz Unimog 435 Service Manual

Refacing
Disassemble cylinder head. referring to 5.1/1.
2 Check valve guides and exchange if necessary,
referring to 6.1/1.
3 Check
valve
seat.
Note: If valve seats show only slight traces of wear,
they can be refaced without necessitating replace·
ment of
valve
seat rings, provided they are not ma·
chined below their bottom limit.
See 1.2/4 for repair size.
4 Introduce special tool No. 14 into valve guide.
5 Position special tool No. 14 and adjust cutter to
seat diameter.
See table on page 1.2/3.
Note: For valve seats with 45
0
seat angles the 45
0
side of the cutter head is for cutting the seat whereas
the 30
0
side is for the clearing cut. For valve seats
with 30
0
angles, the two sides are to be reversed.
6 Reface vallie seat, applying gentle pressure.
7 Measure valve seat runout.
See table on page 1.2/3.
Important:
Check directly after finishing the valve seat. The
guide drift must not be released or withdrawn before·
hand.
8 Measure valve seat width; if necessary, correct
to 70
0
at top and bottom.
See table on page 1.2/3 .
. 9 Re·assembly cylinder head, referring to 5.1/1.
UKD 30 402 21 42-01
Refacing valve seats with hand cutter 01.8
352/352 A
UR01-G152
6.3/1