Changing Valve Seat Inserts; Grinding Valves; Fitting Valves - Valtra 6000 Workshop Manual

21. Engine
F. Changing valve seat inserts
Exhaust valves are fitted with separate valve seat inserts. If the
sealing surface is damaged so badly that it cannot be repaired
with machining, the seat inserts should be changed.
1. Grind the valve head on a discarded valve so that it sits
down in the valve seat. Fit the valve and weld it in place in the
seat. Cool with water.
2. Turn the cylinder head over and knock out the valve and
seat.
3. Clean the valve seat location. Cool the new seat in liquid ni-
trogen until it stops bubbling, or alternatively place it in dry ice.
4. Fit the seat with a suitable drift. Machine the seat.
N.B. Where necessary, standard size seats can be replaced
by inserts with a larger outer diameter. See Specifications.
±0,1
11
48,500...48,525
The inlet valve seat machined direct on the cylinder head, can
be provided with a separate valve seat insert, order no 8366
47936. Machine the seat insert location on the cylinder head
(see figure above). Fit the insert like a seat of the exhaust
valve.
Note! Engines on tractors 8550 and 8750 have the valve seat
inserts also on the inlet valves. From March 96 these cylinder
heads have been marked with letter V, which is stamped on
the cylinder head front upper surface on the exhaust side. As
a spare part these heads can be fitted on all engines. The
V ---marked cylinder heads are also available for the 4 ---cylin-
der engines.
Model
1. 9. 1992
1. 4. 1997
G. Grinding valves
In order to ensure that there is a proper seal around the valves,
there is a difference in the sealing surface angles. Thus there
is a very narrow sealing surface which seals effectively even
after prolonged running.
A
INLET 35˚ ---20'
EXHAUST 45˚ ---20'
1. Grind the damaged valve disc with a valve refacer. Adjust
angles to 45˚ ---20' for exhaust valves and 35˚ ---20' for inlet
valves.
2. If the edge of the valve head is less than 1,5 mm after it has
been ground, or if the valve stem is bent, the valve should be
discarded.
3. If necessary, grind the end of the valve stem.
4. Lap the valves with lapping paste and check the contact
surface with marking paint.
5. Clean the cylinder head and valves of any remaining lap-
ping paste.
H. Fitting valves
1. Check the valve springs for straightness, length and ten-
sion using a spring tester. Compare with specifications.
2. Lubricate the valve stems and fit the valves in the correct
order in the cylinder.
3. Fit the springs, spring guides and valve keepers with the aid
of a lever for compressing valve springs, 9101 66200.
4. Tap the end of the valve stems lightly after fitting the valve
in order to ensure that they are secure.
53
Code Page
6000-- 8750
212 3
A
B
35˚+20'
45˚+20'
B