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Old 01-13-2013, 11:48 PM
Join Date: Jan 2013
Location: Berkeley, CA
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Lightbulb Blue Smoke after Idling/ PRV (PCV, CCV, CVV) Details

Valve Cover and Crankcase Ventilation system details for N62:

Pressure Regulating Valves (PRV) is P/N 11127547058 and is often referred to as PCV, CCV, CVV, or oil separator. This part and post is referring, but not limited to, the N62 engines. There are several versions of this crankcase ventilation system within the N62 family including the updated Valve Cover w/in-tube PRV that my e53 does not have installed. The N62's crankcase ventilation system serves a similar purpose but is very different from the Crankcase Ventilation System w/Oil separator found in M62 in 2000 - 2003 e53s and other BMW models.

My situation, and I believe this to be true in most "blue cloud on acceleration after prolonged idling" situations seems to be caused by vacuum/oil leaks in the crankcase cavity. Uniquely, the N62's PRV requires vacuum from intake AND crankcase - allowing the PRV to be pushed shut by atmospheric pressure through a tiny vent in the PRV cap; it should temporarily open when blow-by gasses are released, creating pressure/destroying the vacuum, into the crankcase. This is why the engine stumbles/dies when the dipstick or oil filler cap are open/leaking. Naturally, something else, like a valve cover/timing cover leak, could prevent a vacuum from forming…leaving the PRV "open" all the time and allowing oil and air (vacuum leak) to flow unabated into the intake.

To prevent seal the crankcase cavity leaks, one needs to thoroughly clean and/or replace the valve cover and all rubber grommets, o-rings, other gaskets that are leaking! So if you did replaced the valve cover seals to no avail, your main vacuum leak is likely originating elsewhere, like mine. I'm not advocating a complete tear down and replacement of all seals, just the ones that failed…very difficult to ascertain. Although, this complete tear down/replace procedure is exactly what is happening in the case of "replace the valve stem guides." Only a vigilant person would certainly fix potential leaks when doing valve stem seals while leaving the heads on. For non-DIYers, many service techs, dealer or otherwise, are just trying to get the job "done"…not "perfect." This can, if you had one of these service techs, can lead to them replacing the gasket but not actually trying to solve the vacuum leak. I, a DIYer - not saying all are like me, did not want to reassemble until I knew, with reasonable certainty, I had found the source of my vacuum leak and could prevent it from recurring upon reassembly.

N62 Valve cover:

On the inside of the valve cover is a covered passageway and a multitude of vents that direct gases to and and divert oil away from the PRV. I did my best to ensure this passageway was as clean as possible before reassembly. The passageway does not appear to be very complicated nor appear to be a complicated "network of passageways" as BMW literature and others have noted. Because of this, I assume most of the cleaning should be concentrated on the sealing surfaces: bolt holes and main sealing groove. Nothing I have read/seen alludes to valve stem seals/guides; especially in my situation. It seems to me that a complete tear down or "remove and replace" would involve cleaning all of the surfaces and replacing the seals/grommets/o-rings. I assume this to be the real "fix" for the vast majority complaints of bluish/white smoke upon acceleration after prolonged idling, in closed loop operation, when no signs of oil are present in a plug read but there is a significant amount of oil in the intake.
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Old 01-14-2013, 10:32 AM
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Join Date: Dec 2012
Location: Reno, nv
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Interesting read, I'm not experienced with the N62 whatsoever....

This thread, along with your other one, are going to prove helpful to many people as the N62 equipped cars start to get up there in age and miles

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blue, oil separator, pcv, smoke, valve cover

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