4. DISASSEMBLY, INSPECTION AND REASSEMBLY OF ENGINES 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 correc- tion, 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]. 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]. 82E-5 – 98E-5 SERIES 4-23 Intake Exhaust Seat cutter angle 120 90 1 2 Grinding wheel angle 40 150