Cyl Head Oil Leak Likely ???

[Roncallo]

Hello

I have an elusive oil leak on my 1988 560SL. I thought it was a rear main seal see photo. I have already done the following.

1) I pulled the transmission and inspected the seal and foud it to be dry.

2) I also inspected the back engine cover and found it to be wet but the wetness appeared to be comming from outside of the bell housing, possibly through the crank position sensor hole or the left side starter hole. I have not discounted the engine back cover but I did not remove it since the manual strongly advised against it unless absolutly necesary.

3) I have noticed the PS appears to be leaking but will not drip even with the steering wheel held hard over with the engine running. Of coarse nothing drips when I'm under it. Also oil on floor looks and feels like motor oil.

4) I am concerned about the rear of the cylinder head. My manuals have a schematic showing the head being feed at the rear. This seems to me to be a very unlikely place to leak oil. I cannot get a good visual inspection of this area. It does appear to be wet but not unusually so. I can get a reasonable look at the valve covers seals, they appear bone dry.

5) It's leaky enough to form a small 10" puddel in my garage after one or two days of use but I cant see any fluid levels deminishing from either the engine trans or PS pump.

I guess my question for the group is what is the most likely sorce of a leak in this area. Has the 560 been known to leak oil from the head? And also if I have to remove the rear cover what is a recommended sealer for this cover.

Thanks You
John Roncallo