VW 3.0 TDI

[mikkhh]

(12-05-2025 )mikkhh Wrote:  Maybe problem arises on engines that have vacuum pump and that will pull air from crank case.

Simple test with engine running remove oil filler cap and see if there is vacuum inside or not. I have yet to see turbocharged diesel car engine that has vacuum inside crankcase with engine running.

Friday night and replacing aftermarket sensors to genuine ones on an Audi (engine runs properly after fitting genuine MAF sensor instead of new no name aftermarket junk), but vacuum pump will pull also AIR into crank case, so there is always positive pressure build up naturally happening.

Oh well that just checked a running example - 4.2 audi v8 Naturally Aspirated engine there is PCV coming directly into the intake manifold, not only just after air filter so that is why this crank case is pulling vacuum at idle and engine speed changes when remove oil filler crap. All of those crank seals etc engine leak point will cause running issues then. Looks even way more headachy system just to save some oil vapours, instead the modern stuff just leaks way more oil externally than there will ever come out of the PCV system on a healthy engine...

Long story short - PCV system on modern stuff is way more complex and creates myriad of issues to get rid of miniscule amount of oil vapours outside of engine.

(12-05-2025 )jmartin Wrote:  I think mikkhh asked for a pic of the damper

Those dampers usually rust away from center part and become loose. Try with your finger to see if it is already peeling loose. Also the rubber changes it's elasticity over time, reducing it's dampening effects.

Have you replaced the alternator freewheel clutch (if it is not freerunning in one way then you will damage belt and also crank dampener) and aux belt tensioner?

With engine running check the crank damper for excessive play and "jumping around"

There appears to be traces of big oil leak in the picture you sent or it is just dirty?