Volvo RWD 900 Forum

Dear maximum.revs,

May this find You well. Yes. The oil breather box - the plastic vessel, to which the flame trap hose connects - may be clogged. This black plastic item is mounted to the engine block, below the intake manifold.

A clogged breather box produces many of the same symptoms as a clogged flame trap: crankcase oil vapour pressure is higher than it should be.

While removing the intake manifold eases access to the breather box, it can be removed, if you've small hands. If I recall correctly, it is secured by a hex bolt. You might want to move aside, the idle air control valve.

There is a gasket, between the oil breather box and the block, that should be replaced.

Hope this helps.

Yours faithfully,

Spook