Cylinder Head Assembly: Service Precautions

CAUTION:
Reface The Valve Seat
Always reface the valve seat after the valve guide has been replaced, and use a suitable scraper to break the sharp corner (inside diameter) at the top of the valve guide. Failure to do so may result in possible valve train wear and/or damage.

Lapping the Valve Seat
The interference angle of the valve and seat should not be lapped out. Remove all grooves or score marks from the end of the valve stem and chamfer it as necessary. Do not remove more than 0.25 mm (0.010 inch) from the end of the valve stem or excessive valve clearance may occur.

Check Valve Face/Seat
If the valve face runout is excessive and/or the pits and grooves must be removed, reface the valve to a true 45-degree angle. Remove only enough stock to correct the runout or to clean up the pits and grooves. If the edge of the valve head is less than 0.79 mm (1/32 inch) thick after grinding, replace the valve because the valve will run too hot in the engine.

If the valve and/or valve seat has been refaced,
If the valve and/or valve seat has been refaced, it will be necessary to check the clearance between the rocker arm bearing surface or valve tappet surface (depending upon application) and base circle of the camshaft lobe with the valve train installed in the engine.

Corrosion Damage/Cooling System Requirements
This engine has aluminum components and requires a special corrosion inhibiting coolant to avoid cooling system damage. Refer to Cooling System for proper specifications and procedures.