Rennlist - Porsche Discussion Forums - Oil leak from Rocker (Tappet) Cover

I have had an annoying leak from one of the tappet covers and this was exacerbated when I last redid the tappets. Found the culprit, there is a plate welded onto the outside of the cover and an opening on the inside where a strengthening pressed web is. Seems someone in their wisdom thought they would fix it by poking some silicon down there, probably worked ok for a while but in recent times of my 3 years of ownership of this Australian delivered 65 912, it has dripped a bit onto the No.1 exhaust. When a new gasket didn't fix it further investigation revealed the cause. It is now filled with solder and shouldn't be a problem in the future, but can anyone tell me why there was a hole there in the first place ? It seems to have had a collar around it which I prized off with a screw-driver as though it was once a breather ? It is not the original engine with the car, it is the same type number, maybe the covers were off a 356 ? 2nd photo shows the flange piece prized off.

This particular cover also had a marked bow in the outer lip of the sealing land which meant that it lost about about 1.5 mm of "push" against the engine mating surface. Not easy to fix, thought about it for a while and ended up placing on some softish wood blocks and with another piece of wood in the middle of the bend hit downwards a bit at a time. Eventually the flange went straight and no damage done, thought this would fix the leak but the hole described above put paid to that.
https://cimg2.ibsrv.net/gimg/rennlis...38e4fbb075.jpg
https://cimg5.ibsrv.net/gimg/rennlis...4a3a7c32c3.jpg

I am new to this forum, also own an Aussie delivered '69 911 and I have to say I enjoy both equally, in fact the 912 is a terrific mid 60's car.

Ed