Fuel tank neck repair

I have a new Roadster tank that is tight other than the gas cap. I have an original cap and have replaced the seal.
I was told I have to build up the sealing surface of the tank. I leaks when its too full. Can I use JB weld to raise the sealing surface of the tank so that the cap snaps tighter, and sand it evenly? I have never used JB Weld before. Tank is not painted yet as I wanted to make sure it didnt leak.
Doesnt look like it would take much to build it up. Will this work or does anyone have a better idea?
Thanks in advance.

I believe they all leak a small amount if you fill it too high. Probably works it's way through the breather hole. Are you sure you have a poor seal? Or are you trying to fill the tank all the way to the base of the opening. 1/2" short is fine.

Actually there are two rubber seals in the fuel cap. The obvious one is the one that covers the mouth of the fuel tank. The other one (which is typically rotted away) is under the 'sealing disc' which is basically a short section of rubber tubing that has a 3/8 inch inner diameter and a 9/16 or 5/8 inch outer diameter and about 7/16 inches long.

If your fuel cap is original and has never been apart, you would need to grind away the center portion of the fuel cap in order to dismantle the cap. Then the cap would have to be drilled and tapped for a machine screw. So make sure that both seals are in good condition before messing with your filler neck.

Part Number: 06-0681/RK
Repair Kit, Flip-Up Filler Cap

Andover-Norton
http://www.nortonmotors.de/ANIL/Norton Website/norton/parts-list.php?pricelistpart=060681/RK

Smear a thin film of light machine oil or light cooking oil on the top surface of the filler neck. Then place a piece of glass on the flat. You should see an even ring of oil under the glass if the surface is flat. Alternatively, after you apply oil to the filler neck, simply put on and take off the cap, then inspect the cap's seal for an even transfer of oil.

I could not get my oil tank cap to seal until I replaced the rubber gasket with one I made from 1/16 inch thick synthetic cork, available from any auto parts house.You might try that approach.

Slick

texasSlick said:

Smear a thin film of light machine oil or light cooking oil on the top surface of the filler neck. Then place a piece of glass on the flat. You should see an even ring of oil under the glass if the surface is flat. Alternatively, after you apply oil to the filler neck, simply put on and take off the cap, then inspect the cap's seal for an even transfer of oil.

I could not get my oil tank cap to seal until I replaced the rubber gasket with one I made from 1/16 inch thick synthetic cork, available from any auto parts house.You might try that approach.

Slick

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The oil method seems to have identified the area. About 1/2 of the seal is dry right where I am seeing the fuel leak out. I am going to try a thin coat of epoxy on the area and sand it smooth. I dont think it needs much of a build up. Does anyone have a suggestion for the material to use? I am thinking less than a 1/16 of an inch of material.

MikeM said:

The oil method seems to have identified the area. About 1/2 of the seal is dry right where I am seeing the fuel leak out. I am going to try a thin coat of epoxy on the area and sand it smooth. I dont think it needs much of a build up. Does anyone have a suggestion for the material to use? I am thinking less than a 1/16 of an inch of material.

Click to expand...

JB Weld or other epoxies should do the trick. I would not use the JB Quick. Auto body filler should work as well.

Rough up the area where you will be building with a file, to give the filler something to "bite" on.

Finally, use a flat sanding block that covers the entire filler neck to make it flat all over.

Good luck with it. Let us know how it turns out.

Slick

PS: clean that oil off the neck before proceeding!!