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Thread: Leaking fuel tank

  1. #1
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    Leaking fuel tank

    Next dilemma: 1967 R60/2. The fuel tank has the tiniest leak. So far I have not found the exact location. I've mounted the tank, full of fuel, an inch above a flat table with clean cardboard under the tank. Over night I get a spot of fuel under the left front of the tank. I'm guessing the seam is leaking but not sure yet. I will continue to investigate.

    So what are my options? I've heard of fuel tank coating but will that cure a leak. Thanks for a little guidance.
    1980 R100T
    1971 R50/5
    G650GS
    1967 R60/2, 1947 James ML

  2. #2
    Liaison 20774's Avatar
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    Yes, finding the leak is the first step. How about blowing some baby powder on the tank in the morning to see where it sticks. If you can catch the hole small enough, it seems that recoating the tank can plug the holes from the inside. I was able to fix a leak on my R25/2 tank that was up near the straps where the front of the tank attaches to the frame. I only spot-coated that area. I used the Caswell products. POR-15 seems to get good comments. Kreem seems to be not worth the effort.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
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    You used it on the outside of the tank? Where I think this is leaking can't be seen. So that would be an easy fix. Coating the inside would mean you have to consider the crossover holes, etc. Don't want to seal those up!
    1980 R100T
    1971 R50/5
    G650GS
    1967 R60/2, 1947 James ML

  4. #4
    Liaison 20774's Avatar
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    No, I used it on the inside. In my case, my tank was uncoated, so I just tipped the tank so that I could pour the sealant in such that it ran to the low point and covered the leak. I'm now paying for the fact that my tank came to me uncoated...I'm going to have to get the inside cleaned up and recoat completely.

    First find out where it's leaking, then go from there. Maybe it's leaking from your petcock?? But, you'll need to attack this from the inside and there are ways to plug the crossover outlets as well as the petcock opening so they don't get plugged.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  5. #5
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    The leak is assessable .
    Attached Images Attached Images
    1980 R100T
    1971 R50/5
    G650GS
    1967 R60/2, 1947 James ML

  6. #6
    Liaison 20774's Avatar
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    Same situation as my R25/2. I hope you can find a way to seal it from the outside. I would try to remove the fuel to below that point and then inspect the area with some high magnification. See what is really the issue. Difficult to weld/braze with fuel in the tank. I've heard of people emptying the tank, and swirling air or car exhaust inside the tank to knock down the fumes. But any heat on the outside will likely mar the paint. Might be the quick choice as opposed to relining the tank.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  7. #7
    I sealed a K75 tank seam with an external fuel tank sealer I got at an auto parts store. It came in a corn-dog type roll with the two epoxy parts to be sliced and mixed together. It lasted 5 years and then I had to redo it. I cleaned off the bad paint before applying the sealant.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  8. #8
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    You should be able to have that welded or brazed. Small tanks are pretty easy/convenient to “gas clear”. On larger tanks I push out the oxygen (atmosphere) with a continuous nitrogen flow.
    If you have a radiator shop nearby, give them a look at it.
    OM
    "You can do good or you can do well. Sooner or later they make you choose." MI5
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    2009 F800GS 1994 TW200

  9. #9
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    No flame involved with one of those big ol' soldering irons. I wonder if I can clean it up well enough to flow solder around that area. Surely I don't want to mess up the paint too much. But in that area a bit of brushed paint would work for me. I'm not much of a purist!

    I will check out Paul's suggestion. Won't cost much if I go that way. Thanks for the great input. I will report back when it's fixed.
    1980 R100T
    1971 R50/5
    G650GS
    1967 R60/2, 1947 James ML

  10. #10
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    The big old copper billet, heated with a torch style may do it. You already know the importance of things being clean so you should be headed in the right direction.
    OM
    "You can do good or you can do well. Sooner or later they make you choose." MI5
    Mod Squad
    2009 F800GS 1994 TW200

  11. #11
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    Took it to the Industrial Radiator place. Know for soldering fuel tanks also. The man looked at it and said he could solder it. He took me in back and showed me a motorcycle gas tank that he "red coated". He suggested red coat instead of solder. He is doing the job for me. I will trust his judgement.
    1980 R100T
    1971 R50/5
    G650GS
    1967 R60/2, 1947 James ML

  12. #12
    Liaison 20774's Avatar
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    Nice! Let us know how things work out. You can always get more aggressive if this doesn't work out.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  13. #13
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    The fuel tank is fixed, installed and no longer leaks. He charged me less than $30.
    1980 R100T
    1971 R50/5
    G650GS
    1967 R60/2, 1947 James ML

  14. #14
    Liaison 20774's Avatar
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    Sounds great! What does it look like?
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  15. #15
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    Well as for the bike, it is pictured in #6 in the "what about the seat" thread. As for the red coat, you can't really see it. The interior of my tank is in very good shape. Red colored. The red coat he installed is all up in front of the tank.
    1980 R100T
    1971 R50/5
    G650GS
    1967 R60/2, 1947 James ML

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