Tools Required

1. Inspect the cylinder head gasket and the cylinder head mating surfaces for any of the following conditions:

1.1.

Leaks

1.2.

Corrosion

1.3.

Blow-by

2. If the cylinder head gasket has failed, determine the cause from the following list of conditions:

2.1.	An improper installation

2.2.	A loose or wrapped cylinder head

2.3.	A missing or not fully seated dowel pin

2.4.	A low torque on the cylinder head bolts

2.5.	A warped cylinder block

2.6.	A scratched cylinder head surface

2.7.	An excessive inlet manifold torque

2.8.	A cracked engine block tapped hole

Important: Do not use a motorized wire brush on any gasket sealing surface. Do not scratch the valve stem surface when using a wire brush. Do not attempt to weld the cylinder head. Replace the cylinder head if necessary.

3. Clean the cylinder head bolts.
4. Clean the cylinder head. Do this by removing any varnish, carbon, and soot the bare metal.
5. Use a suitable tool in order to clean the valve guides.
6. Use a wire brush in order to remove any carbon from the valves.
7. Soak the valve in a carburetor cleaning fluid in order to remove any varnish.
8. Clean the threaded holes on the cylinder head.
9. Inspect the cylinder head deck for signs of corrosion, sand intrusion, and porosity.
10. Inspect the cylinder head for cracks, especially between the valve seats and the exhaust ports.



11. Inspect the cylinder head deck and the intake and exhaust manifold surfaces for flatness.

11.1.

If the mating surfaces are out of flat by more than 0.1 mm (0.004 in), mill the surfaces.

11.2.

Replace the cylinder head if more than 0.25 mm (0.010 in) of the metal must be removed.

12. Inspect all of the threaded holes for damage. If necessary, recondition the threads with thread inserts.



13. Inspect the cooling jacket plug seating surfaces.
14. Inspect the valve seats for excessive wear or burn spots. Properly clean the valve guide if the valve seats need reconditioning.
15. If the valve guide needs reaming, measure the valve guide clearance in order to determine if an oversized valve is required.
16. If a valve is burnt, recondition the valve seat insert. Do this by grinding the valve seat.

16.1.

Do not remove more than 2 mm (0.079 in) of the valve seat material.

16.2.

If the new valve seat is too wide after grinding, narrow the valve seat by using a 70° stone.

17. Inspect the valve stem tip for signs of wear.
18. Inspect the valve lock and the oil seal grooves for chipped or worn lands. Replace the valve if any of these conditions are found.
19. Inspect the valve face for signs of burning or cracking. If pieces of the face are broken off, inspect the corresponding piston and the cylinder head for signs of damage.
20. Inspect the valve stem for burrs or scratches. Remove any burrs or scratches with an oil stone.
21. Inspect the valve stem for straitness. Do this by using V blocks.
22. Inspect the valve head for bending or distortion. Replace any bent or distorted valves.
23. Inspect the valve face for grooves. If a groove is so deep that refacing the valve would result in a knife edge, replace the valve.
24. Grind the valve face to specifications if the valve face is otherwise in good condition. Replace the valve if the valve face cannot be ground within specifications.
25. Inspect the valve spring dampers for any broken pieces or cracks. Replace the valve spring dampers if any of these conditions are found.



26. Inspect the valve springs for free length.
27. Inspect the valve springs for bent spring end.
28. Inspect for cracked or broken valve springs.



29. Inspect for low spring tension (load open and closed)
30. Replace the valve spring if any of the above conditions are found.
31. Inspect the valve spring seating surface of the spring caps for signs of wear, cracks, and gouging. Replace the seating surface if any of these conditions are found.
32. Measure the valve margin after grinding the valves. Replace the valve if the margin is less than the minimum recommended margin.



33. Measure the valve guide clearance. Do this by using one of the following methods:

33.1.

Insert the valve into its guide. Lift the valve 2 mm (1/8 in) off of the seat. Move the valve from side to side while measuring the amount of movement with a dial indicator.

33.2.

Measure the guide ID with a hole gauge. Measure the valve stem with a micrometer. Compare both of the measurements.

Notice: Clean the valve guides before reaming. Packing of chips or carbon may result in the reamer jamming into the valve guide or broken reamer flutes.




34. If necessary, ream the valve guide oversize and install an oversize valve.