Hi again,
OK I am in bad luck i guess .....
after I measured the pressure (I posted the readings a few days ago) I
realized its really oil pressure and not electronics or other stuff. OK
got the muffler off, got the tin sheet off (I really hate this f!@#$%
sheet), and the engine support bracket. Unfortunately, the water pipe
did not allow to unscrew the upper nuts completely, so in the end I had
to get the pulley off and then the water pipe.

I did not make any mistakes with the gaskets. Everything as it is
supposed to be. BUT I do see quite obvious new scratches in the cover.
Together with the bit of oil that I saw at the pump after I ran the
engine a bit, it looks like I have some backpressure and a blockage
somewhere. Any other ideas? Hm in cold run I got 55psi at 1000rpm. Only
when it warmed up, I had 12.5psi at 2000rpm (and 3 meters of tubing
before the gauge, which will drop the pressure a bit, but not that much
I guess). Also that was still beofer the fan of the radiator went on,
but the engine was quite hot already.

I have to admit I don't know what to do any more. I just don't want to
open the beast again ..... I checked all oil gallys with an air pump and
felt air coming equally out of every opening. I could not sense any
obstacle sitting somewhere. Also the indication of the new scratches on
the cover rather show some backpressure than too loose bearings or
similar. I sanded the old cover flat before I put it on (now I have a
new cover ready to be put on). Also the scratches show that all areas
are equally scratched, so i did not flatten it at an angle.

Hope someone can help me. Oh man, I hope i could drive around now, and
now it seems that all effort wasn't worth it (besides the gain in
knowledge about these engines ...)

I need rum now
Cheers
Thomas