Hypothetically speaking, if you can blow air through your PCV/Breather system (i.e. blowing through a hose at the flame trap location will cause a paper towel placed over crankcase fill opening to blow right off) is it fair to say that your breather system is not obstructed? Just wondering if there is a definitive test for plugging before I dive in and spend an afternoon pulling the intake manifold on our 960.

A recent blown rear cam seal has taken me down this path. I thought the box had been replaced when we purchased the car 25k miles ago, but now I wonder. Volvo dealer claims there is no definitive test for breather box plugging.

Switching it over to synthetic oil and very short OCI until I can clean it up a little. Still might go ahead and replace the breather box and hoses.

Thanks

Andy R.