Refacing The Valve Seat; Replacement Of Valve Seat - Mitsubishi 6M60-TL Service Manual

CYLINDER HEAD AND VALVE MECHANISM
11-38

Refacing the valve seat

• Grind the valve seat using a valve seat cutter or valve seat grind-
er.
• Place a piece of sandpaper of approximately #400 between the
cutter and valve seat and grind the valve seat lightly.
• Use a 15° or 75° cutter to cut the valve seat to a width within the
standard range.
CAUTION
• Make sure that the valve seat refacing does not cause the
valve sinkage to exceed the specified limit.
• Lap the valve and valve seat.

Replacement of valve seat

[Removal]
• The valve seats are installed by expansion fitting. To remove a
valve seat, grind inside the metal stock to reduce the wall thick-
ness, then remove the valve seat at room temperature.
[Installation]
• Check that the diameters of the valve seat holes in the cylinder
head conform with the values shown below.
Intake side
Diameters of the
valve seat holes
Exhaust side
• Replace the cylinder head if necessary.
• Chill the valve seat thoroughly by immersing in it in liquid nitro-
gen.
• Install the valve seat in the cylinder head using
• Lap the valve seat and valve.
Inspection: Cylinder head bottom surface distortion
• If the distortion exceeds the specified limit, rectify it using a sur-
face grinder.
CAUTION
• Make sure that the height of the cylinder head from the top
surface to the bottom surface is not reduced to a value be-
low the specified limit.
+0.025
φ42
mm
0
+0.025
φ38
mm
0
and
.