Conditions/Conclusions

Conditions

A new, improved type of piston ring was introduced into engine production from cars with engine number 396323 and later.

If the engine consumes more than 0.4 liters of oil/1,000 km (0.68 qt/1,000 miles) (complaint limit), the following should be checked to give guidance as to whether the consumption problem lies in the cylinder head, the crankcase ventilation or in the piston ring/liner surface.

Check:

- Check spark plugs

Check if the spark plugs are damaged, coated with carbon etc. and replace if necessary.

- Check leak down

Perform a leak down test.

- Check cylinder compression

Perform a compression test.

- Remove the intake manifold

Check to see whether there is a film of oil or droplets of oil in the cylinder head intake passage and/or oil on the upper side of the valve stem/valve crown.

Conclusions:

If the intake passage and the valves are free of abnormal amounts of oil and:

- oil consumption, previously acceptable, has gradually started to increase rapidly

- oil consumption lies between 0.40 - 0.80 liters/1,000 km (0.68 - 1.36 qt/ 1,000 miles).

this indicates a problem in the piston, piston ring or cylinder liner surface.

Faults in valve stem seals or internal leakage in the cylinder head, for example, cannot be completely eliminated.

If

- oil consumption has always been high

- there are traces of oil on the intake passage and the valves

- oil consumption is above 0.80 liters/1,000 km (1.36 qt/1,000 miles)

the problem is probably in the cylinder head. (See also page 7.)

The cause may here be:

- leaking valve stem seals

- internal leakage in the cylinder head

- another fault in the crankcase ventilation other than blockage.