Conclusions for corrective action

Replacing piston rings 

As a first corrective action the piston rings should be replaced. Normally only the scraper ring and the oil ring must be replaced. The compression ring should only be replaced if absolutely necessary.

Replacing valve stem seals 

If traces of oil are found on the valve crowns, in the ducts or on the valve stems, the valve stem seals should be replaced.

Thoroughly check the cylinder head. Check for internal leakage.

Replacing the cylinder head 

If traces of oil (described above) are found and faults are found on the cylinder head, internal leakage for example, the cylinder head must be replaced.

Replacing the cylinder block and pistons 

If damage is found in the cylinder block (worn cylinder bore, deep scratches etc.) the cylinder block, pistons and piston rings must be replaced.

Replacing the engine 

The engine must be replaced if the problem cannot be remedied using the above corrective actions.