Oil Separator Box
 

1991 Volvo 240 142,000 miles, automatic, California car with EGR valve.
I suspect the oil separator box is clogged because the flame trap components are clean, and there is excessive crankcase pressure. I tend to believe that the crankcase pressure is not able to get out due to the oil box. Is there a clear cut method for determining if the oil box is clogged?
Anyone out there have a clear picture of a cross section of the oil box showing the path of the fumes that enter from the crankcase?

Hi,

There are cross section photos on google as people have cut them open and shared photos.

They’re almost impossible to clean thoroughly, so if yours is clogged buy a new one direct from Volvo- they’re still available and not at all expensive.

Cheers

Is there a way to know if the oil box is clogged while it is on the car?

Pull off one of the pipes and connect another of suitable length and blow down it. See if you can feel anything blowing out of the filler cap on the rocker cover.

Not sure if your car will be the same:~

On my '88 240 Estate the oil box is quite easy to remove (just awkward I suppose) but no need to disturb any other parts.. manifold etc.
Done the job as a precaution but once removed gave it a clean out with a degreasing agent (easy job) reused the original unit without any problems.

Some advice on the forum exists relating to leaving the flame trap off if you wish.
Regular oil changes will keep the system clean.
Bob.

I think that means leaving out the small plastic filter thing with holes which is inside the flame trap, not simply removing the entire flame trap. The connected pipes are important and still have to go somewhere.