This article introduces how to calibrate the valve seat of yanmar 3TNV series and 4TNV series engines
For Yanmar Diesel Engine Agriculture Excavator Tractor Marine Generator Diagnostic tool
[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].
09.2024 Yanmar SA-Direct 2.45 Offline Diagnostic Software
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].
