Whistling noise coming from the top of the engine

veramayboy · Post by **veramayboy** » 11 May 2010, 14:38

I have a Volvo S Non-turbo with 138,000 miles. At the top of the engine and near the left side, there is a high pitch whistling sound. When I take the oil cap off, the noise disappears. Does anyone know what that means?
Thanks,
Veramayboy

Moondust70 · Post by **Moondust70** » 25 May 2010, 07:33

This is due to a blocked oil separator which is part of the PCV system (positive crankcase ventilation).

The separator is under the inlet manifold and it is easier to replace rather than clean..............

If you leave it then there is a strong chance that the crankcase pressure will get too high and blow oil from the seals, usually at the back of the engine block.