1993audi90

Replacing valve cover gaskets today, and as part of the R/R procedure, I always scotchbrite the sealing surfaces where the gasket seals on the head side.
What I found is, on both cam caps with the round (front cap passenger side, rear Cap on D.S) are stress cracked in the surface where the valve cover seals. The cracks does not appear to extend into the area of the cap where the two nuts are holding the cam cap to the head. The "V" cam cap on both sides appears to be fine.
I just snagged some cams out of a pic a part and took the cam caps. I did not see any cam bearing in the head side--do the cams not have separate bearings?
I also do not see that Audi sells the cam caps separately.
The driver side is in the rear--which I could probably switch out fairly easy.
The passenger side though will not be pleasant--the front cap also holds the seal, and this is the seal right behind the timing gear.

Lago Blue

Negative. I've not heard of this either. I'll have to look for this next time. What could the cause be? Did you take a photo you could post? Yes, I think the cams runs just in the alu. head and caps.

1993audi90

Negative on the photo until i pull the valve covers to replace those. Unfortunately i can not find a part no. for these specific cam caps, both end caps i described have cracks. And spare cam caps have on the shelf also have cracks--albeit much smaller. The passenger side front i could blame on the wrong size cam seal, but the DS rear? Theres no seal there and it is cracked too. Im thinking this is stress related and due to poor design or not enough material on this cap. The v shaped caps are fine. Anyone putting some serious hp on the engine may have probs..

CRAZY_RUSSIAN

what you are talking about is most likely just casting marks and not cracks, oil and dirt gets in them and makes it look like cracks