What is the mechanism by which the PCV system increases vacuum to the crankcase while idling and decelerating? I am still getting some smoke, buy only at idle and letting up on the gas.

 

Hi,

Before Tech or other experts reply with more accurate info, here's my assumption on the PCV system.

Unlike PCV-valve systems, Volvo's PCV system totally relies on the intake vacuum, which sucks the crankcase pressure via the oil trap and put it back into the combustion chamber. But there also seem,s to be a baffle plate inside the oil trap, and if you want to clean it, you really gotta get serious. If it were my car, I would just put the new one in and not worry about it for the next 100,000 miles.

I hope this gives you some hints.


JPN

 

Hi Kanji and Jmana,

On my car (96 na) there is a small vacuum line that runs
from the flame trap holder back to the vacuum tree. I
believe this line provides vacuum for the crankcase at
low rpm through a small hole in the flame trap holder.
I think I read that in a post a while back.
On my car the hole is totally clogged, I cannot push
a needle through with pliers-it's hard to believe there
ever was a hole there.
If I'm wrong on this someone please correct me.

Best of luck, John