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Old 10-19-2012, 04:59 PM
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bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
 
Join Date: Mar 2008
Posts: 20,167
Mein Auto: 02 BMW 525i M54 auto 130K
Quote:
Originally Posted by Steve530 View Post
There must be some opening in the tube that allows the oil to enter the drain hose, but I have not yet found that.
Looks like nobody knows the answer to that question, least of all me.

But, I came here just now to cross link this post today to here, for the record:
> E39 (1997 - 2003) > Cute little trick to diagnose blocked CCV system...
Quote:
Originally Posted by Zakov View Post
So the fuel pressure regulator in M52, connected to CCV is operated with crankcase vacuum?
Quote:
Originally Posted by rdl View Post
I have an M54 so I'm not really familiar with your engine. I have though seen the pictures and diagrams of the air hose off the CCV running to the fuel pressure regulator.

When if first saw those pictures a couple of years ago, I was baffled at the design intent. I finally realized that "operated with crankcase vacuum" is technically accurate. But assuming the CCV is working properly it is really so close to atmospheric pressure that it makes no practical difference. The CCV regulates crankcase vacuum to less than 15 millibar, or 0.15% different from atmospheric pressure.

I think the purpose of taking a reference pressure this way is to provide clean, filtered source of atmospheric pressure to the fuel pressure regulator without any chance of engine bay dirt, grit and grime fouling the sensitive parts of the small fuel pressure regulator. By comparision, the CCV is about 3 inches in diameter & much less sensitive to dirt. An awkward, klugey way to achieve the result in my opinion.

For the M54, BMW changed the design to take atmospheric reference pressure from the F fitting in the boot between the MAF and inlet manifold. That supply is kept clean by the engine air cleaner.
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Last edited by bluebee; 10-19-2012 at 05:02 PM.
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