Corrective Action, Conclusions

Replacing piston rings

The piston rings should be replaced first. Use piston-ring kits 272270-0 (dia. 81.0 mm = 3 3/16") and 272271-8 (dia. 83.0 mm = 3 17/64").

The new type of piston rings is included in these kits.)

Normally only the middle and lower piston rings should be replaced. The upper ring should be replaced only when necessary. See "Replace piston rings".

Replacing valve stem seals

If traces of oil are found on the valve crown, in the ducts or on the valve stem, the valve stem seals should be changed.

Carefully examine the cylinder head to see if there is any internal leakage.

Replacing cylinder head

If traces of oil are found as above and defects in the cylinder head are discovered, indicating internal leakage etc., the cylinder head should be replaced.

Replacing engine block and pistons

If damage is discovered in the cylinder block (worn cylinder bore, deep score marks etc.), this should be replaced, along with the pistons and piston rings.

Use the following cylinder blocks for each engine. Engine Cylinder block, P/N

B5254FS 271933-4

B5252S 272173-6

B5234T 272176-9

The above cylinder blocks include pistons with the new type of piston rings.

Replacing the engine

The engine should be replaced if the problem cannot be solved with any of the above corrective measures.