I have a 2002 A6 with a 3.0 just did the timing belt. wasn,t leaking any oil when I started. I replaced the o-ring on the cam bolt cap and it leaked so I pulled out my o-rings a put the fatest one I could squeeze in there and it leaks. I can see the oil spun around the cam pully and it puddles in the bottom crease of the cap when it's not running.It's only the inside top one on the driver side all the others are fine. I am going to try three things. I am going to lower the oil level to the 1/2 way mark on the dipstick in case it's a pressure issue and I am going to re-torque the bolt and seal the ring in with some gasket seal. The cap isn't cracked. Has anyone experienced this? I'm going to pull the valve cover too and recheck the new gasket.

 

Yes, the cap itself is the seal, if it leaks just replace the cap.

 

Thing is these have the removable o ring I replaced the o- ring. I also checked the cap itself for cracks. I just don't understand why it's leaking but I'll order a couple new caps they can't be much. I'm more curious as to why when I stuffed the largest o-ring I could around it and put it back in snug. At the moment I am more worried that I have created to much oil pressure by filling to the top line on the stick that's why I'm going to try to empty it to the 1/2 way mark. Just wondering if anyone else has experience this problem and knows the reason why.