Mitsubishi diesel engines - Replacing the Valve Guide; Inspecting the Valve Face

ENGINE MAIN PARTS - INSPECTION AND CORRECTION
2 - 20
1.7 Replacing the valve guide
(1) Using a punching tool, remove the valve guide
from the bottom to the top of the cylinder head.
(2) Using a press, insert a new valve guide from the
top of the cylinder head so that the valve guide
protrusion above the cylinder head face is to the
indicated dimension.
(3) With the valve guide press-fit into position, insert
a new valve to verify that it slides smoothly
inside the valve guide.
(4) Check the valve face-to-seat contact.
1.8 Inspecting the valve face
(1) Apply a thin coating of red lead onto the valve
face. Then, using a valve lapper (available on the
market), check the valve face-to-seat contact.
(2) The valve face contact area with the valve seat
should be uniform and in the middle of the face.
If not, reface with valve facer.
(3) If the measured valve head margin (valve head
thickness) is less than the limit, replace the valve.
Unit: mm (in.)
Standard
value
Limit
Valve head margin
1.35 to 0.65
(0.0531 to 0.0650)
0.5
(0.0197)
Valve guide protrusion
above the cylinder head face
Inspecting the valve face
Valve seat-to-face contact
Valve head sinkage
Red lead
Valve lapper
Valve head
sinkage
Valve head
margin
Valve guide
Cylinder head
10
0.5 mm
(0.39
0.20 in.)
[15 mm]
(0.59 in.)
Good
Bad
Contact area
(in the middle of the
valve face)