Komatsu 4D98 Series Shop Manual page 57

4. Engine Body
If the seat surface is slightly rough-
ened: perform [A] and [B] below.
If the seat is heavily roughened but the
width is almost normal, correct with a
seat grinder or seat cutter first. Then
perform lapping [A] and [B] below.
If the seat is heavily roughened and the
width is much enlarged, grind the seat
inner surface with a seat grinder whose
center angle is 40", then grind the seat
outer surface with a grinder whose cen-
ter angle is 150" to make the seat width
match the standard. Then perform seat
correction as described in 0, and then
carry out lapping [A] and [B] below.
Grinding wheel
angle
0, %
40
150
[A] : Lap the valve and seat with a mixture
of valve compound and engine oil.
[B] : Lap with engine oil only.
'
Seal angle
correction angle Y
Grin&one
Seat grinder
I
Valve lapping
4-9