Mitsubishi S3L Service Manual page 62

CYLINDER HEAD AND VALVE
MECHANISM
Valve lapping
tool
Figure 71 Checking valve contact with seat
Good
Contact must be uniform
around the complete
circumference.
Figure 72 Valve and valve seat contact
Valve sinkage
Figure 73 Valve margin and sinkage
62 / 195 62 / 195
Prussian
blue
Bad
Valve margin
ENGLISH
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.
Item
Valve margin (lip
thickness)
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.
Item
Valve sinkage
(dimension from top (0.020 ± 0.009 8)
of closed valve to
face of head)
Service Manual Mitsubishi SL-Series diesel engines
INSPECTION
Unit: mm (in.)
Standard Limit
1.0 (0.039) 0.5 (0.020)
Unit: mm (in.)
Standard Limit
0.5 ± 0.25 1.5
(0.059)
Version 08/2004