DIY Solution to M54-M52TU CCV problems

[Joshdub]

Originally Posted by bcredliner

IMO there is no connection to eliminating the oil consumption and that it is good, or bad, for the engine. Would anyone do this on a new car?

This has been discussed to great length on other forums. According to them, the M54 has low tension oil rings. Increasing crank case vacuum helps these rings seal, stopping oil consumption. Oil consumption seems to be hit or miss on M54s, but this has been a documented issue since they were first released. I'd wager that is why there is the extra capped vacuum port on the CCV and the corresponding capped port on the intake manifold. Funny enough, running a vacuum line from the CCV to the intake manifold (as shown in realoem) significantly helps, if not cures, the oil consumption issue.