my understanding is they create a vacumm in the crankcase to draw fresh air thru it,and suck the air out at the same time.Strangest system I've seen.as on my car i believe a blow by valve is damaged,so if I can't clean it,I will block vac line to crankcase valve cover and vent thru the top,to throttle body.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt