87
4.2.6
Valve seat correction
[NOTICE]
Always check the oil clearance between the valve and valve guide before correcting the valve seat. If it
exceeds the limit, replace the valve or valve guide first to make the clearance satisfy the standard. After
correction, wash the valve and the cylinder head sufficiently with diesel oil to remove all grinding powder
or compound.
1) If the seat surface is slightly roughened: perform
[A]
and
[B]
below.
[A]:
Lap the valve and seat with a mixture of valve
compound and engine oil.
[B]:
Lap with engine oil only.
2) 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]
.
intake
Exhaust
Seat cutter
angle
120
90
3) 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 center angle is 150
°
to make
the seat width match the standard. Then perform seat
correction as described in 2), and then carry out lapping
[A]
and
[B]
.
1
2
Grinding wheel
angle
40
150
