SaabCentral Forums banner
1 - 3 of 3 Posts

·
Registered
Joined
·
1,366 Posts
Just minutes ago inserted a new one into my '97 (the white plastic cylindrical thing?) Arrow towards the Throttle body I believe.
Be 100% sure by blowing thru it... it's purpose is to stop Boost from going into the valve cover
 

·
Registered
Joined
·
3,938 Posts
Correct. The arrow indicates airflow direction and you want airflow to go from the cam cover to the intake manifold and not the reverse. If the flow goes the other way then boost pressure will pressurize the crankcase and eventually blow oil past the seals, not good.

Under boost the crankcase is ventilated the other direction through the larger diameter hose leading from the same fitting in the cam cover but down to the compressor intake.

You will understand that the PCV circuit can only draw in crankcase blowby under manifold vacuum. If the manifold is under boost pressure the PCV circuit has to find a lower pressure point to draw in the blowby, that happens to be at the compressor inlet when the turbo is boosting. So these engines have two PCV circuits controlled by that innocuous looking valve. It is a critical part.
 
1 - 3 of 3 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top