11
11-37
• If the red lead deposited on the valve indicates a poor contact
pattern, take either of the following corrective actions.
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.
Contact pattern Corrective action
Minor defect Lapping
Serious defect Reface or replace valve and valve seat
To Next Page
Loading...
