Help ID this leak

[BrianS]

Can someone help me determine what is the cause of an oil leak on the backside of the head? I have been working to try and address the other leaks but don't know to address these. I have previously replaced the oil return tubes, the valve cover gaskets (twice) and the oil tubes going to the cam tensioners. Each of the previous were leaking oil someplace or another. The first time I had the valve covers off, I checked to make sure none of the head bolts were broken.

Thanks!!!

PS: The car is a 1987 911 cab with 81k miles.

[jrbennett]

My guess would be the rocker shafts.
Next time the valve covers are off, try tightening the rocker shafts.
Otherwise possibly between the heads and cam housings.

[vesnyder]

I had similar leaks and put the rocker arm O-rings on and no more leaks. Give it a try.