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Is your catch can routed to atmosphere or to manifold vacuum? If manifold vacuum how to you take care of crankcase venting when the engine is under heavy load and producing no vacuum?
 

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I can share my crankcase venting of the e46 if interested. It mimics how my e23 turbo, e28 and e34 turbo are vented. They all have venting of the crankcase under all engine conditions.
 

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Here is the simple CCV system used on all 80's bimmers with the m30 engine (e28, e23, e34).




This is the system I copied and used on my e39 and e46. How it works.

1. At idle crankcase vapors are purged mainly via the small vacuum hose which is under manifold vacuum and little bit through the ICV which bypasses the throttle. Nothing is flowing past the throttle since it's essentially closed at idle.

2. Under cruise and whenever the throttle is open crankcase vapors are purged through the larger crankcase vent hose and through the throttle. This flow path especially important when the engine is under load conditions when there is very little manifold vacuum. If you measure the vacuum with a vacuum gauge at the throttle when it's open you should measure vacuum.

cheers
 

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Any metal wools or bird nest inside the catchcan? How is the oil consumption since zero oil caught and drained back?
I don't want to hijack this thread more than I have so I'll answer succinctly as possible. No and zero. None of of bimmers burn any oil between changes.
 

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I have not done the bag for not due to the fact of at idle if I took off the oil fill cap, I had to pry it off almost with how much crankcase vacuum there is.
Did you connect to manifold vacuum or to the distribution piece on top of the manifold?

I'm curious, why do you guys believe that driving around with that much crankcase vacuum is a good thing?
 

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Well good luck then. Your assumptions will affect how you troubleshoot the issue.

Anyone have specs on what the crankcase vacuum in inches of water column pressure should be?
 

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oops. 6.5" of water.

6.5" of mercury is almost 90" of water, mercury being far denser than water.

t
uses an industrial HVAC manometer, and can confirm that 5"- 7" is normal.
Thanks for the clarification. I'm seeing 1.9 inches of mercury or 25 inches of water on mine.
 
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