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oil leaking at headstock cover

bll230

Hot Rolled
Joined
Jun 14, 2007
Location
Las Vegas
I have been able to eliminate just about every leak except for the headstock cover. I originally had a new cork gasket from Monarch. Leaked. I cleaned the cork and reinstalled with Hylomar both sides. Leaked. I have made two new gaskets from different thickness material. Both leak.

The tach gears sling the oil so energetically that the oil starts weeping where the arrow is, and then the leak slowly progresses around the entire cover.

I traced this because I had oil wicking between all the covers, and in cleaning all the oil off and watching, it turned out that this leak was the cause of all the wicking.

Is there any way to seal the cover plate? I guess my next solution would be silicone seal like on a car engine oil pan.

IMG_0937.jpg
 
Yamaha used to, and may still, make (probably just private label, really) a product called Yamabond. It was a non-hardening sealant meant for sealing dirtbike cases that couldn't have a traditional gasket. I wonder if that's a candidate?

ETA- it appears they still make it, Yamabond 4.
 
Have you put the cover on a surface plate, upside down and looked to see if the cover is not flat, but distorted by the fasteners pulling it against the soft gasket material and making the cover have a high spot or weak-tension spot where the leak is?
You might be able to make the cover flat again or even better, a slight curve against the leaking location; a bit of added tension at the leak location. and try again with a new gasket and a good sealant.
The problem is not a fault of the gasket or the sealant, it is lack of proper pressure or tension in that location.

Several additional ways to stop the leak at that location:

The best way and the most professionally appealing way: drill and tap an extra hole and add a screw there. There is too much distance and not a straight line between the two fasteners adjacent to the leaking location.

You could see if you could make a splash shield that protected the leaking location from a direct spray off of the gears. Rivet or weld the spray-shield to the underside of the cover.

Use longer fasteners at the two adjacent locations and make an aluminum 'bridge' to span between them, Make this bridge at least 1/4" thick so it will not flex easily like the cover does. The bridge could have a slight bump in the middle over the leaking location to add additional pressure there.. Just a few .001"s.

Or: dry off the metal and gasket surfaces, clean of all oil. Use Permatex Ultra-Black or Grey sealant/gasket maker with a new gasket. Give it 24 hours to set. Do not use an excess amount, you don't want blobs of excess sealant to be in the gear box.

DualValve
 
That Yamabond is a remarkably good sealant! My 51 ee has a flat sheet metal splash plate with a round screen located just under the filler hole. It still has a dry gasket on the heavy iron top cover, the splash plate seems to prevent oil from seeping out.
 
The Yamabond description sounded a lot like the Hondabond I used on my 1996 Integra, which did work well. After a bit of searching I find that Yamabond is the same product as the Hondabond, and I fortuitously still have an almost full tube sitting in the garage, so that will be my next attempt.

Thanks for the advice.
 
Update - I used the HondaBond, with 1 mm spacers between the casting and the plate when I pressed the plate into the Hondabond.

No leaks.

Thanks for the suggestion.
 








 
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