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Thread: Plastic welding leaky tank flange?

  1. #1
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    Plastic welding leaky tank flange?

    I'm sick of dealing with epoxy, especially after I found out JB weld doesn't hold up to ethanol!

    I want a permanent fix. So I though about using a plastic welder to melt nylon rod onto the tank to fill the low spots, then sand flush.




    Any thought? Bad idea? Good idea? Have I gone mad?

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    Update: Doesn't work


    It sticks, but will still chip off if I pry at it. The problem is, in order for it to bond, the base needs to melt too. Too risky.


    Is there ANY expoxy out there that will bond to plastic and resist ethanol? I don't want to spend $45 on a caswell sealer again when I just need to seal the flange. It would take maybe 2oz.
    Last edited by jmccalip; 03-30-2012 at 03:42 PM.

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    apriliaforum expert anzacinexile's Avatar
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    Your problem is the tank isn't nylon, its fiberglass and that's a thermo-setting plastic which wont melt - it'll burn but not melt so it wont bond no matter how much heat you use.

    The only thing you can use is more fiberglass resin in a roughed up and clean crack. If the crack is big you might need to use some glass filler
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    apriliaforum expert DanV990's Avatar
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    Quote Originally Posted by anzacinexile View Post
    Your problem is the tank isn't nylon, its fiberglass and that's a thermo-setting plastic which wont melt - it'll burn but not melt so it wont bond no matter how much heat you use.

    The only thing you can use is more fiberglass resin in a roughed up and clean crack. If the crack is big you might need to use some glass filler
    The tank is Nylon 6, also known as PA6 or Polyamide 6, not fiberglass. The same as the tanks on 01 and up RSV, Tuono, KTM, and a large number of Ducatis. They are all rotational molded nylon tanks made be Acerbis. If the Falco tank was Fiberglass people would not be having the problems swelling due to ethanol in the fuel. Ethanol is hygroscopic, meaning that it actively pulls water out of the air. The nylon molecules in the tank then pick up and absorb water from the ethanol from the fuel and expand.
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    Is nylon a true thermo plastic? I didn't think it could be remelted without losing some of the mechanical properties.

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    Quote Originally Posted by TRXnMe View Post
    Is nylon a true thermo plastic? I didn't think it could be remelted without losing some of the mechanical properties.
    Yes, nylon is a thermo plastic.


    I think I'm gonna try it again. Most of the surface was smooth when I tried it, and that's where it flaked. The part that was roughly sanded held so well I couldn't scratch it up.


    And I found another use for zipties, haha! I found some 6-6 nylon zipties and I'm using them to melt onto the flange.

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    apriliaforum expert anzacinexile's Avatar
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    Quote Originally Posted by DanV990 View Post
    The tank is Nylon 6, also known as PA6 or Polyamide 6,
    Bugger me, you learn something every day
    Chris
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    Quote Originally Posted by jmccalip View Post
    Yes, nylon is a thermo plastic.


    I think I'm gonna try it again. Most of the surface was smooth when I tried it, and that's where it flaked. The part that was roughly sanded held so well I couldn't scratch it up.


    And I found another use for zipties, haha! I found some 6-6 nylon zipties and I'm using them to melt onto the flange.
    Handy to know about the zip ties, metal and plastic share one thing in common when being welded, the filler material has to be right

    I knew nylon was thermally formed, but I had an idea it could not be reground and reformed as a 'true' thermo plastic can, there are a few plastics like that, nice to know I'm wrong

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    apriliaforum expert futfalc's Avatar
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    I bet waterproof liquid nail would work.That stuff sticks to anything and when hard gets rock like.
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    Quote Originally Posted by futfalc View Post
    I bet waterproof liquid nail would work.That stuff sticks to anything and when hard gets rock like.
    Once again I decided the plastic welding doesn't work. My gun does not get hot enough to bond mutiple layers together. OK for the first few, but not once I get past 1/8".

    I ordered Devcon Flex-weld to use instead.

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