Valves

GENERAL INFORMATION

Valve Stem Tip Wear Pattern

1. VALVE STEM TIP.

2. VALVE KEY GROOVE.

3. LEAST WORN AREA OF STEM.

4. MOST WORN AREAS OF STEM.

5. FACE.

6. MARGIN.

Measure

PROCEDURE.

Valve-to-seat misalignment. Lift the valve off the seat and apply a thin layer of Prussian blue to the valve face. Lower the valve onto the seat, press and

gently rotate it. The paint marks on the seat face show the

concentricity of the valve and seat. Wipe off the paint. Apply a thin layer of Prussian blue to the seat face and repeat the check. The paint marks on the valve face show the alignment of the valve and seat. If the valve face does not seat properly, machine the face of the parts

by grinding or replace the valves.

by grinding or replace the valves.

Inspection

PROCEDURE.

Wear of the valve stem tip. Pitting and wear of the valve key grooves and seal grooves. If the grooves are defective, replace the valves.

Check the valve face for pits and cracks. If the face is badly damaged, inspect the corresponding cylinder bore and piston. Check the valve stem for scoring and scratches. Light scoring and shallow scratches can be removed with a fine abrasive stone. Check the straightness of the valve stem and warpage of the head. Use V-blocks as valve supports.

Check the valve stem for scoring and scratches. Light scoring and shallow scratches can be removed with a fine abrasive stone. Check the straightness of the valve stem and warpage of the head. Use V-blocks as valve supports.

Replace bent or distorted valves.

Check the valve face for a concentric groove. If the groove is deep and grinding the valve face will leave a sharp edge, replace the valve.

Replace if necessary. The valve face may be reground to

nominal dimensions, if the valve is otherwise serviceable for

further use. If the valve face cannot be reground, replace the valve.

Measure the valve head margin thickness after grinding. If the margin thickness is less than the specified value, replace the valve.