Inspecting Valve Face; Refacing Valve Face - Mitsubishi Heavy Industries SL Series Service Manual

INSPECTION AND REPAIR OF BASIC ENGINE

1.7 Inspecting valve face

Apply a thin coat of Shinmyoutan or equivalent lead-free
coloring paste on the valve face, and strike the valve face
against the valve seat using a valve lapper to check for
contact condition. If the contact is not even, or any defects
are found, or if the limit is exceeded, reface or replace the
valve.
Note: (a) Inspect the valve face after the valve guide is
repaired or replaced.
(b) Do not rotate the valve when pressing the valve
face coated with Shinmyoutan or equivalent lead-
free dye against the valve seat.
(c) Always lap the valve and valve seat after the
valve has been refaced or replaced.
Item Nominal
Valve
seat 45°
angle
Valve
Valve 0 mm
seat
sinkage [0.00 in.]
Seat 1.6 mm
width [0.063 in.]
1.5 mm
Valve margin
[0.059 in.]

1.8 Refacing valve face

If the valve face is significantly worn out, reface the valve
face using a valve refacer.
Note: (a) Grind the valve face using the valve refacer at the
specified angle.
(b) Secure the valve margin width equal to or greater
than the limit. If the dimensions after refacing
does not meet the specified values, replace the
valve with a new one.
6-4
Standard Limit
- -
0.25 to 0.75 mm 1.50 mm
[0.0098 to 0.0295 in.] [0.0591 in.]
1.30 to 1.80 mm 2.50 mm
[0.0512 to 0.0709 in.] [0.0984 in.]
1.35 to 1.65 mm 0.50 mm
[0.0531 to 0.0650 in.] [0.0197 in.]
Valve lapper
Refacing valve face
Bad
Good
Contact
(must be at face center)
Contact between valve seat and valve
Valve head
sinkage
Valve sinkage
Valve refacer
Refacing valve face
Shinmeitan
Valve head
margin
Set the valve face
angle at the specified
angle.