Lapping; Inspection: Valve Seats; Valve Seat Width; Valve Sinkage From Cylinder Head Bottom Surface - Mitsubishi 6M60-TL Service Manual

• If the red lead deposited on the valve indicates a poor contact
pattern, take either of the following corrective actions.
Contact pattern
Minor defect
Serious defect

Lapping

• Lap the valve in the following sequence.
• Apply a thin coat of lapping compound to the seat contact sur-
face of the valve. Adding a small amount of engine oil to the lap-
ping compound can facilitate even application.
CAUTION
• Do not put any compound on the stem.
• Start with an intermediate-grit compound (120 to 150 grit) and
finish with a fine-grit compound (200 grit or more).
• Strike the valve several times against the valve seat while rotat-
ing the valve a little at a time.
• Wash away the compound with diesel fuel.
• Apply engine oil to the valve contact surface of the valve seat
and rub in the valve and seat well.
• Inspect the contact pattern of the valve and valve seat again.
• If the contact pattern is still defective, replace the valve seat.

Inspection: Valve seats

(1) Valve seat width

• If the measurement exceeds the limit, reface or replace the valve
seat.
• After refacing or replacing the valve seat, make sure to lap the
valve seat and valve.

(2) Valve sinkage from cylinder head bottom surface

• Perform measurement keeping the valve in close contact with
the valve seat.
• If the measurement exceeds the limit, adjust or replace the de-
fective part(s).
• After refacing or replacing the valve seat, make sure to lap the
valve seat and valve.
Corrective action
Lapping
Reface or replace valve and valve seat
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