I changed the oil on my 1972 914. When I start up the motor, oil starts leaking through by the top of the crank case. There is no oil leaking from the strainer. When I try and tighten the bolt it doesn't tighten at all. Is this a bad sign? Any ideas? What is that bolt for?

Where on the case of the motor ... front, rear, right or left side? Leaking on the case seam?

And if you are overtightening the strainer bolt you will create one hell of a problem as in a broken case.

It's leaking out of a bolt on the passengers side. The 13mm one.

Can you post a picture, with you pointing your fingure to where you think it's leaking?

It may be the crankcase breather . There should be a hose there, but sometimes po's plugs them. Can you take a pic?

Maybe the through bolt copper seal that holds the top of the oil pick up

.Is the cooling flaps pulley missing on the left side of
the engine? (or oil pressure sensor?)

(as you were)