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Service Manual Mitsubishi SL-Series diesel engines
Version 08/2004
ENGLISH
CYLINDER HEAD AND VALVE
MECHANISM
INSPECTION
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4. Valves
1) Put a small amount of Prussian blue or red
lead on the valve face. Hold the valve with a
valve lapping tool (commercially available)
and press it against the seat to check its
contact.
2) The width of contact must be uniform all the
way around both seat and valve. If the contact
is bad, reface the valve and seat.
3) If the valve margin (valve lip thickness)
exceeds the limit, replace the valve.
Unit: mm (in.)
4) If the valve sinkage (the dimension from the
top of a closed valve to the face of cylinder
head) exceeds the limit, recondition the valve
seat or replace the cylinder head assembly.
Unit: mm (in.)
Figure 71 Checking valve contact with seat
Valve lapping
tool
Prussian
blue
Figure 72 Valve and valve seat contact
Good
Bad
Contact must be uniform
around the complete
circumference.
Figure 73 Valve margin and sinkage
Valve sinkage Valve margin
Item Standard Limit
Valve margin (lip
thickness)
1.0 (0.039) 0.5 (0.020)
Item Standard Limit
Valve sinkage
(dimension from top
of closed valve to
face of head)
0.5 ± 0.25
(0.020 ± 0.009 8)
1.5
(0.059)
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