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Ron Dame
03-10-2017, 08:17 AM
What, if anything should be used with the cork/rubber fuel sender gasket? A few years ago, mine started leaking, so I replaced it. a few weeks later it was leaking again, and I was able to tighten the screws a bit more and stop the leak. Then the sender failed, so I installed a new one with a new gasket and new copper washers. That was fine for a while, but it is leaking again.

I don't know if it is just my Champ or all Champs, but the hole in the floor board is not in good alignment with the sender, 3 screws cannot be reached and the sender won't come out of it, so the whole operation requires me to lower the tank and work. I don't want to have to do it anymore, so what should I use to ensure it stays sealed?

Jeffry Cassel
03-10-2017, 10:58 AM
Usually use a little RTV on it and have not had trouble. Be sure you have the oil and gas resistant kind

r1lark
03-10-2017, 11:13 AM
Ron, I have used a small coating of K&W CopperKote or similar spray on the cork gaskets. Honestly, I have not had good luck with the rubber gaskets in this application, but have had really good luck with cork. You can buy cork in sheets/rolls and cut your own in true CASO fashion. :)

Also, I have had much better luck using the original style copper-asbestos annular washers versus just a flat copper washer. New production annular washers made with graphoil material instead of asbestos are available - I think they are widely used in aircraft - if you can't find originals.

Another thing to look at closely is the screw holes in the tank. Over tightening in the past can pull the metal up around the holes. This will cause the sender "plate" to bottom out on these higher areas versus uniformly compressing the gasket.

Ron Dame
03-10-2017, 11:18 AM
Ron, I have used a small coating of K&W CopperKote or similar spray on the cork gaskets. Honestly, I have not had good luck with the rubber gaskets in this application, but have had really good luck with cork. You can buy cork in sheets/rolls and cut your own in true CASO fashion. :)

Also, I have had much better luck using the original style copper-asbestos annular washers versus just a flat copper washer. New production annular washers made with graphoil material instead of asbestos are available - I think they are widely used in aircraft - if you can't find originals.

Another thing to look at closely is the screw holes in the tank. Over tightening in the past can pull the metal up around the holes. This will cause the sender "plate" to bottom out on these higher areas versus uniformly compressing the gasket.

I don't recall what they were, but the washers were whatever SI sent me. I wasn't looking closely, did not know they made anything else but solid copper that small. The gasket is one of the rubber/cork mixtures that came with the sender as well. de-burred teh top of the screw holes last time, so should be flat. It seems like the gasket just compresses over time and needs to be retightened, but might as well use sealer too. t would not be so bad if this were a car, but even if teh hole in the floor was over the sender unit, I still would have to take the seat out.

Lynn
03-10-2017, 12:03 PM
None of the silicone RTV's are suitable for gas. Some will say "gasoline resistant". But it will not hold up to constant exposure to fuel.

Ron Dame
03-10-2017, 12:05 PM
That's what I thought, Aviation Permatex was OK until ethanol came along.


None of the silicone RTV's are suitable for gas. Some will say "gasoline resistant". But it will not hold up to constant exposure to fuel.

56GH
03-10-2017, 02:08 PM
My solution to the leakage problem with my former 56J was to use a "Chevs of the 40s" P/N 1516061 gas tank sending unit cork/rubber composition gasket, since it's the same as a Studebaker ($2.25 in the 2012 catalog.) I used McMaster-Carr Standard Thredseal washers P/N 750-0002-10 instead of the copper washers. See the 56J Only web site and the newsletter for 56jon079.pdf 02-2013 on page 5, Mail Bonding, for a better description and pictures.

Bill L.
'62 GT

TWChamp
03-10-2017, 03:25 PM
I cut my own cork/rubber gasket to seal the sender on my 50 Champion, and it held up fine. When I removed the tank to flush it out I did notice the gasket got wavy, so it did react to the crap gas somewhat. I made another new gasket, and it's also sealing fine. I didn't use any sealer on the gasket, but I think I used a touch of Aviation Permatex on the 6 copper washers.