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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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Discussion Starter · #42 ·
Have not checked the tensioner but the first time the it sprayed everywhere the tensioner was dry. Just replaced the vc cap. I’m considering the vc being cracked but would it have that much pressure to spray everywhere.
 

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2001 325i MT, 2001325i ZF auto,1999 328is auto
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I had this problem some months ago, I was trying to lower the crankcase pressure. I was using an adjustable valve on my catch can. With the pressure restricted to low, my back-pressure was going positive under running conditions. I was getting the same oil throw Plus I thought I had blow the rear main seal. Therefore I took the restriction off and the oil leaks disappeared, including the rear main seal.
Positive crankcase pressure was causing my problem. Good Luck
 

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I’m considering the vc being cracked but would it have that much pressure to spray everywhere.
It depends on if CCV is stock or home brew, and working or not. You might have a positive pressure crankcase instead of negative with a working stock CCV. Cover the oil dipstick tube with an empty plastic bag tight, and see if running engine will suck the air out of bag or add more into it.
 

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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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Is it possible there is excess pressure in the crankcase that is forcing it out at VC? maybe CCV acting up? I need more coffee to think that one through, but it has to be coming from someplace over there, and there arent many possibilites in that corner..
 

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'03 325iT Mystic Blau
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Is it possible there is excess pressure in the crankcase that is forcing it out at VC? maybe CCV acting up? I need more coffee to think that one through, but it has to be coming from someplace over there, and there arent many possibilites in that corner..
He's replaced the CCV with a catch can, so there's a whole slew of possible (probable) variables there regarding crank case pressure.
 

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No, the leak cannot get to the washer bottle.
I had an E30 leaking oil into the glove box. It was the oil pressure switch pushing oil into the harness all the way to the ECU. Who'd a thunk it! I started putting a razor slice into every E30 I serviced on the oil pressure switch plug as it was really sealed. Probably not his issue but he's having a hard time finding the leak.
 

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Several people recently reported oil shooting out of the dipstick tube. If that can happen there, why not out of faulty Vc or Vcg? What else is there on the front Ŕ corner of the engine?
 

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Many days and many posts and no idea of the source. I posted a simple way to establish the leak location(s). I think for some OPs the conversation is more fun than solving the problem.....
 
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Chitchat for the win!!!

I have an oil cap drilled for a low pressure gauge-
I think MATT should try measuring crankcase pressure,
on the road, under load.

That's what I'd do, anyway

t
around the water cooler.
 
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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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This doesn't look less complicated than stock, just more easily accessible. Not sure I understand the system, but existing connections both upstream and downstream of the throttle body can cause a number of issues.

Agree with TobyB it would be useful to measure crankcase vacuum levels.
In my own experience with the CCV system, that's the quickest and the most informative test.
 
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