Weird leak location on cyl. head cover?

[CrazyCloud]

So I noticed that my '78 GS 750E was leaking a little bit of oil on the number one cylinder side of the cylinder head cover, out of the cosmetic cover cap towards the front of the bike. I took off the cap and wiped away all of the oil; assuming that it was leaking from the half moon plug. However, it is quite clear that the oil is coming from inside the screw hole for the cover cap . It's not a gusher of a leak, but is making a mess dripping on the fins and getting flung onto the spark plug wire for no 1.

To test for sure I put some teflon tape on the screw for that hole and it greatly slowed the leak-- so it seems that is where it's coming from. Has anyone ever seen this before? Is there anything I could cover the screw with that could withstand engine heat, but be removable and seal up the threads?

I did have the cover off to adjust the valves, but didn't drop it, etc. I put new OEM gaskets on the breather and the cyl. head cover. I swear I did a search and didn't find anything. Thanks in advance for any guidance. This site has really taken a lot of the frustration out of getting this old bike up and running again; it has made the wrenching fun instead of a chore. So thanks!

[Steve]

I will venture a guess that somebody was running a tap in the threads to clean them up and went just a little too deep, punching a hole through the back.

One suggestion for repair would be to take off the valve cover and look on the other side of the hole. If you can see a puncture, GREAT. Clean the area impeccably with carb cleaner spray, brake cleaner, whatever you have that will CLEAN all the oil from that area. Mix up some JB Weld and sprad it around the hole, let it set up overnight.

The BEST way would be to have it welded up, but the JB just might do the trick.

.

[CrazyCloud]

Thanks Steve, that sounds like a better idea than gooping stuff on the threads. Next time I have the tank off I'll give that a try. The back of the hole is definitely gone, I didn't even think about a tap knocking it out...sounds like something I would do!

[Sandy]

For now just put a very small dab of non hardening gasket sealer on the screw and then maybe repair it next time it's apart. I have a valve cover bolt the was doing the same thing probably due to imperfect gasket hole on the inside and allowing oil into the bolt area. Sure took a while to find that one. Anyway, after inspecting the outside of the gasket to make sure it wasn't actually misaligned I just removed the bolt, put some sealer on it and put it back. No more leak and I'll deal with it at the next valve adjustment.