Man D 2866 LE 401, Repair Manual

Page: 93 / 138

4
Replacing valve seat insert
92
Installing valve seat insert
Fig. 4
Heat cylinder head to approx. 80
_
C (175
_
F) in
water bath.
Cool new valve seat insert to approx. –200
_
C
(–330
_
F) and insert it in the cylinder head.
Carry out check by driving it in until the stop is
reached using pressing tool.
Install valve guides.
Note:
When the valve seat inserts have been
changed, the valve seats must be reworked.
3534
Notes:
D
After temperature equalization, machine valve seats.
D
After machining, clean cylinder head and check for leaks using leak testing device.
D
If the cylinder head is excessively heated (above +200
_
C, +390
_
F) the core hole covers (end
covers) loose their tightness and must be exchanged.
D
To do this, clean core holes, blow out channels and press in new core hole covers with
”LOCTITE 648” and pressing mandrel (special tool, see page 133).