Valve Seat Refacing, Valve Seat Replacement

Inspect the valve seat for signs of overheating and uneven contact with the valve face. If necessary, either refinish (machine) or replace the valve seat.

Before refacing the valve seat, inspect the valve guide for wear. If the valve guide is worn, replace it first, and then refinish the valve seat. Refinish the valve seat using the special tool (cutters) or on machine equipment. The valve seat contact width must be within the standard values, and the contact pattern must be even and centered on the valve face. After refinishing the valve seat, lap the valve to the seat using valve lapping compound.

VALVE SEAT REPLACEMENT

1. Machine (cut out) the old valve seat from the inside to reduce the wall thickness.

2. Bore the cylinder head seat bore to accept the oversize valve seat (larger outside diameter).

3. Heat the cylinder head to approximately 250°C and press the new oversize valve seat into the cylinder head seat bore.

4. Lap the valve to the new seat using valve lapping compound.

Valve seat contact width:

Intake valve: 0.8 - 1.2 mm Exhaust valve: 1.3 - 1.7 mm

OVERSIZE VALVE SEAT BORE TABLE