um... there is supposed to be a stud there, not a bolt...
it's possible that whoever put the bolt in, damaged the head...
take the valve cover OFF, and clean around the area, and take a picture of what's there, also, clean the inside of the valve cover where the bolt is touching, and photograph it as well.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!