PSA about Timing Belt Engine Oil Leaks
 

I am not sure if this is documented already, but I figured I would provide some information about members who are have a slight oil leak from the back of each valve cover; which isn't fixed by changing the valve cover gasket. The valve cover gasket or the half moon seals are most likely not the source of the leak but rather a round camshaft seal pictured below:

https://cimg5.ibsrv.net/gimg/www.aud...a2c803fa02.jpg

The seal is not in any of the part diagrams I have checked. They fail because the inside edge of the seal gets really brittle and cracks, Im assuming its the heat cycles and being so close to the exhaust. I was able to chip away the seal just with my finger nail. Lastly, if anyone is changing the camshaft adjusters, like I currently am, this is a required seal if you don't want to delay your reinstallation.

That's good info jbell. I purchased my A8 after the timing belt was changed and it wasn't very long before the smell of burning oil was present. Had the camshaft seals replaced and all was good.
Thanks for the PSA!

Yep. When/if I went into deep head work on a 4.2, I changed those. 4.2 heads (the casting itself) are the same and reversible from side to side of the motor if you look carefully. Thus that plug seals up what would be where the cam pulley attachment point is on the cam that sticks out the "front" of a given head for the belt drive.

My fault! I did not replace the cam plugs when I did the timing service. Hope she is still treating you well.

She is treating me well, a pleasure to drive!

Thanks - I discovered a small oil leak in my garage under my S8 and the dealer confirmed the camshaft seal was leaking. $650 to fix....sound about right?

It's less than I paid:(

Dealer hourly rates vary by location. When they were $105.00 an hour by me, they were $180.00 in Chicago.
Location, location, location......