DIY Solution to M54-M52TU CCV problems

[Xelo]

I must revive this thread upon new findings regarding the amount of vacuum the M54 pulls after this modification.

In latest SIB 110308 BMW states the amount of pressure/vacuum inside the M54 crankcase must be ~16 mBar (that is 0,48inHg). As measured while using the FRAM FV345 PCV valve, the vacuum is 12-15 inHg (or +500mBar). That is over 30x the limit the engine was designed for, this is insane!

And this amount of vacuum is at idle ! Please imagine what letting off throttle/decelerating at 3-4-5K RPMs will do to the level of vacuum
This will no doubtly damage seals/orings inside and deprive the oil pump of oil, lowering oil pressure for brief moments on decelerations.

I have not met another engine in the world where upon opening the oil cap that much vacuum is present. This is wrong and must be addressed as this modification transforms a Closed Crankcase Ventilation system into a Positive Crankcase Ventilation system, but without all the elements needed for such a PCV system to work.

Inside classic PCV systems/engines, there is a continuous air circulation inside the crankcase because there are 2 holes letting the crankcase breath: first one lets the blowby exit being sucked by the intake through the PCV and the 2nd one lets fresh filtered air inside the crankcase in order to: 1) limit the amount of vacuum being built 2) properly vent all areas of crankcase in a wide range of engine RPMs
Usually this 2nd hole sucks air from the intake downstream (after) of filter/MAF/MAP but before (upstream) throttle - where the vacuum is low when throttle is closed.

By removing the CCV (OK), plugging the dipstick drain hole (not OK) and rerouting the crankcase blowby venting directly into the intake (OK) you have designed an incomplete PCV system. One has to allow the block/crankcase to be vented with fresh air from a clean source otherwise it would be like sucking air from a plastic bottle: something/somewhere will colapse and those will be either your VCG or rear main seal.

By venting the block through a 2nd hole you are punching a hole in that plastic bottle you are sucking air out of: while the sucking is still there, the bottle will not collapse anymore as some small venting/air is let in keeping it vented.

If this worked for some of you it does not mean is a right thing, the engine was not designed for this amount of vacuum - and this is BMW's statement as you can see.

You need to provide clean measured source of air to the crankcase while using the PCV. This can be easily done through the vacuum F connector in the intake boot with a T connected to the dipstick previously plugged while a check (one way) valve is installed to prevent air/pressure from the crankcase going up to the intake.