Fuel cap leakage

M

mcwinter

Active member
When I fill my cub fuel tank near the top such that fuel can slosh up to the cap, some fuel leaks from the cap seal. It has the larger supposedly safer fuel cap (don't remember if it came that way or if I obtained one through IH). I don't see anything obviously wrong with the cap or filler neck. I did recently purchase the filler neck repair tool for use on other tractors but haven't tried it out yet. Would it be worth reforming the neck or replacing the cap, or is some small amount of leakage expected when the tank is near full?
 

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I added a second gasket to mine. I just cut one out of some rubberized cork gasket material. Its a little tight but works great. No leaks!
 
I had 2 gasket on mine and that worked for some time. But then I noticed that it got hard to screw on and off and started to leak again. I took the gas tank to the Bash and some of the guys used the tool on it and fixed it. Dosent leak a drop now and gas cap is back to one gasket.
 
I do not see any evidence of the tabs sticking down and the mating surface that needs to be flat appears to be bent down. You need to address the issue by using the tool designed to properly form the mating surface.
 
I observed the same as Bill noted. The cap should turn to a hard stop against the tabs, at which point the gasket should be properly compressed. I bet you can keep turning that cap to the right until it is free to remove again.
 
Upon further inspection, the stop tabs are definitely bent back away from the filler hole. Also the inside sealing surface on the top of the neck is bent slightly downward around a good portion of the circumference. I believe the bent sealing surface is the primary leak cause. I have tried to install the forming tool previously on a similarly deformed B filler neck, and it seems the bent tabs and bottom edge of the neck need to be pre-bent back out at least close to vertical before installing the tool so that this edge isn't smashed out of shape when the tool is compressed. I looked at some of the threads on this topic, but didn't see any suggestions for best tools to use to pre-bend out the neck bottom edge down inside the opening. Have tried screw drivers, pliers, mini pry bar so far. I plan to get a 90 degree needle nose pliers to try next. Any other tools folks have found useful in this constricted space?
 
I use a screwdriver to carefully bend the tabs and then put the tool in. I've never had to pry the sealing surface up and I've fixed some that were pretty severly bent. The job in done in stages. Make an initial press, rotate the tool, press, rotate, press, rotate and continue until the surface is flat -- all the way around.
 
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