Oil anti-flowback valve?

[3C4M Guy]

Recently my 3.2L VR6 engine has been making terrible rattling noises on the first start when not driven for several days. A cold start on the next day is no issue. I believe this is not a timing chain issue (already replaced) but oil starvation. The rattling continues for 4-5 seconds until oil pressure builds and begins to flow. Does this engine have an anti-flowback valve? Is it accessible without delving into the inner workings of the engine?

[MIG]

Look at page 28 on this SSP https://vwcampersite.files.wordpress...fsi_engine.pdf The pump keeps ~200ml of oil in a mini "Oil Tank" to allow fast oil pressure.

If you are getting rattling, I would be looking at the chain tensioners, can you post a video of the noise?

[Umai Naa!!]

Swap the chain tensioner out.

Make sure you bleed it up with fresh oil.

[3C4M Guy]

Thank you MIG and Umai Naa!! for your help. Also thank you for reminding me about those VW self-study programs. I have a similar 68 page document from VW of America.

The reason I did not suspect a timing chain issue is that both chains, the main tensioner and the camshaft adjusters were all replaced 45,000 km ago. Also the noise is not there for every cold start. I left the car unused for 3 days over the weekend. When I started it today, there was no noise. However if the car if not used for a week, the noise will be there. I'll look for an opportunity to record it. In the meantime, I suppose I can't eliminate either the chain tensioner or the mini oil tank. I wonder which is easier to replace? I guess the tensioner?