Cylinder Head - Inspection (Cont'd) / Valve Seats
EM-174prose procedureInspection (Cont'd)
VALVE SEATS
Check valve for any evidence of pitting at valve contact surface, and reseat or replace if worn out excessively.
When repairing valve seats, check valve and valve guide for wear beforehand. If worn, replace them. Then correct valve seat.
The cutting should be done with both hands for uniform cutting.
Replacing Valve Seat for Service Parts
- 1Bore out old seat until it collapses. The machine depth stop should be set so that boring cannot continue beyond the bottom face of the seat recess in cylinder head.
- 2Ream cylinder head recess.Reaming bore for service valve seat [Oversize 0.5 mm (0.020 in)]: Intake 37.500 - 37.516 mm (1.4764 - 1.4770 in); Exhaust 31.500 - 31.511 mm (1.2402 - 1.2406 in)Reaming should be done to the concentric circles to valve guide center so that valve seat will have the correct fit.
SEM795A - 3Heat cylinder head to a temperature of 150 to 160°C (302 to 320°F).
- 4Press fit insert until it seats on the bottom.
- 5Cut or grind valve seat using suitable tool at the specified dimensions as shown in S.D.S.
SEM635A - 6After cutting, lap valve seat with a lapping compound.
- 7Check contact condition of valve seat.
CAMSHAFT VISUAL CHECK
Check camshaft for scratches, seizure and wear.
See also
S.D.S.