Leaking petcocks

[FMF MX]

Anyone tell me how to stop these italian petcocks from leaking? They're as tight as I dare, and it seems to be leaking from around the threaded portion that sticks out from the tank. Any help would be appreciated. Now I know why old ktm's had rags tied around the petcocks..

Bart Carrigan

[Cathump]

Try some teflon pipe tape. You can get it at any hardware store.



 

[Steve Minor]

If the gasoline reacts with, and breaks down the teflon tape, try "pipe dope". It's a semi-liquid thread sealer (about the consistency of toothpaste) that plumbers use....it's cheap and any home supply store will have it.......

 

[tlanders]

I believe you are saying that the gas is leaking between the nipple sticking out and the fiberglass tank. One of my nipples was doing this. Last night I took a Dremel tool with a very small bit and cut the fiberglass down to beneath the jell coat and color to the clear fiberglass in a tight circle about an eigth inch wide around the nipple. Then I took a small pick and scraped/cleaned the metal and any soft fiberglass residue until it looked clean. This took a long time, I felt like a dentist must feel digging out cavities!!! Then I cleaned the area with Acetone, mixed up some fiberglass resin and applied it sparingly to the cleaned area, trying to keep it off the threads. It looked great this morning before I went to work, I will put gas in it tonight and see if it is still leaking. I let you all know. Teddy

 

[FMF MX]

OK, I tried the pipe tape, but the gas melted it. I'll try the pipe dope next. The resin idea sounds like it requires patience, skill, and knowledge..Which probably leaves me out..Are those threaded nipples just stuck into the tank glass? Or are they threaded into something..My tank was powdercoated, and it goes right up to the threads. I hate to start chippin away at it. Will gas melt the pipe dope? Anyone?

Bart Carrigan

[Rocket]

Bart
Loctite makes a product called PST.  It works really great and not affected by chemicals.  That should seal the thread area.
Probably have to buy it at a industrial supply store, possibly auto supply too.
Rocket

 

[tlanders]

My fix is totally successful. I trailered the bike to Kansas City that weekend (265 miles) for the first MOVMX races, raced it in two motos, and it is still dry as a bone. If any other of my tanks leak between the nipple for the petcock and the fiberglass, I will fix them the same way. Teddy

 

[Steve Minor]

Great......please tell how you fixed it?

 

[tlanders]

Steve, read my post on this page on 3/15. If it is too confusing, call me at 417-256-2002days, 417-256-0699eves. Teddy

 

[john durrill]

If the leak is from the threads or the fiber gasket that seals the mouth of the tank nipple, Permatex # 2 non hardening will stop the leak. its impervious to gas and oil and will clean up with alcohol. put it on the threads sparingly and a thin coat on the fibergasket at the bottom. that will seal it. if its a crack in the fiberglass Teddy has the quick fix for that. you can get the permatex at any auto supply store.
hope this helped.
john

 

[FMF MX]

OOOOOKKKAAA Now...SUCCESS!! I chipped the glass out from around the nipple and sealed that with fiberglass resin. Then I used the permatex #2 like John said, (I just happened to have some from fixing the head gasket on this thing) and she leaks no more..Thanks to all for your help..

Bart Carrigan