Fuel Leak

Discussion in 'Motorized Bicycle General Discussion' started by Smallwheels, Jun 7, 2010.

  1. Smallwheels

    Smallwheels New Member

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    My Tanaka PF 3300 gas tank has a crack. It leaks a tiny amount when full. I tried sealing it with Quick Steel which is a two part putty that when mixed gets hot and becomes solid. That fell off.

    Next I tried liquid JB Weld epoxy. It worked for a week. Now the fuel has either broken the bond it had with the tank or perhaps the vibration of the motor weakened its grip.

    What can be used to seal a tiny crack on a fuel tank? I need to be able to find it locally in a hardware store. I've seen fuel tank repair putty that is just the same as the Quick Steel. Instead of being packaged in a cylinder it is two flat strips of white and black putty. It costs about ten times more because it is only two small strips instead of a thick tube for the same price.

    The crack is very short and runs along a seam. I wish the tank were metal instead of plastic. This problem wouldn't be happening. I suppose there aren't too many companies out there making high quality products these days.

    A new tank would cost about $30 with shipping expenses. These things aren't exactly standard stock parts so I can't pick one up off the shelf.

    Let me know of your successes with stopping tiny fuel leaks.
     
  2. Kevlarr

    Kevlarr New Member

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    Buy a new tank. Almost all plastic fuel tanks are made out of polyethylene plastic and there isn't a glue on earth that will stick to it. The only thing that could possibly fix the leak is heat with a soldering iron but being that it's a gas tank I would highly advise you against it.
     
  3. 2door

    2door Moderator
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    Kevlar is right. Poly is tough to repair but if you're sure that it is free of gasoline fumes, COMPLETELY...then it can be 'welded' with a soldering gun. It takes some practice, and it'll stink like h*ll but it can be repaired with some time and patients. I have never found an adhesive that will effectively stick to poluethylene. JB weld is a joke and regular silicone will break down under gasoline. There is one product that you might try before resorting to heat. I've not used it on plastic but it did repair a steel tank that had a crack in a threads in the petcock bung. Look for a product called SealAll. Its available at some auto parts stores and is compatible with gasoline and formulated for fuel tank repairs on lawn mowers, etc. It does require that all oil is removed from the surface so read the instructions before using it. Good luck. Let us know how you make out.
    Tom
     
  4. Cabinfever1977

    Cabinfever1977 New Member

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    I used Gorilla glue, a piece of hose,plus a couple of clamps to fix a leaking pressurized metal fuel line on a car i used to have and it worked great, it stopped the leak.

    Gorilla glue sticks to everything, don't get it on your hands, it wont come off.
     
  5. dag_29307

    dag_29307 New Member

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    I agree with 2-Door Seal-all is an excellent product and it should adhere w/out falling off. As far as prepping the tank, empty it out of fuel let it sit for about an hour or two then put some rubbing alcohol swish that around real good so some seeps out the crack therefore cleaning it as well then let it sit to dry then use the Seal-all and let it dry completely. Once dry you should be able to sand and paint.

    Seal-All Contact and Sealant Adhesive 1109
     
  6. Smallwheels

    Smallwheels New Member

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    Seal-All sounds great. Thank you for the tip. I'll visit a couple of auto parts stores on my way home from work and look for it.

    I used alcohol to clean the tank the last time in addition to sanding the area to be coated with epoxy in order to make the surface rough enough to hold. I didn't clean out the inside with alcohol. Maybe that was the missing step.

    I hope Seal-All is a common product in my area. Do you think it might be sold at places like Home Depot or Loews?
     
  7. Cabinfever1977

    Cabinfever1977 New Member

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    I think i saw it at lowes next to the jb-weld and other adhesives and glues.
     
  8. Smallwheels

    Smallwheels New Member

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    I went to the web site of the marketer and it said it was available at Home Depot. I went there after work and found it in the paint department. I'll probably wait until the weekend to do the work on the tank. Right now I just put a metal can under the tank at night and catch any slow fuel drops that drip. It isn't even enough to create a tiny puddle.

    This stuff looks promising.
     
  9. GearNut

    GearNut Active Member

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    I have had excellent results with Seal-All. I have used it on all sorts of things, from a gasket dressing (gotta work fast) to a leak stop on rain gutters.
    It seems to be tempermental with surface preparation though. Make it squeaky clean from oils and grease. I use lacquer thinner with a final wipe when I can.
    I doubt that you will be disappointed with it.
     
  10. Smallwheels

    Smallwheels New Member

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    Seal All is a failure at bonding plastic. I used it in two ways. One was to put it around a place where I felt there was a fuel leak. So far after just one day there is no fuel coming out of that place.

    The other way it was used is as a contact adhesive. The instructions explained about cleaning the areas well. I did that with degreaser and then alcohol. I put the Seal All on each part of the plastic to be joined. I let each cure for five minutes before joining the parts together. This morning I assembled the air cleaner where the glue had been applied and rode to work. To be safe I attached the parts with small strands of wire in case the glue didn't hold.

    When I arrived at work 8.2 miles away everything was together. When I got home I examined the air cleaner and saw that the Seal All did not make a strong bond and the plastic parts had separated.

    I really want to find a velocity stack that will mount to my carburetor. I don't know of any shops that have them. They did exist because Tanaka actually sold a kit that had one as part of a carburetor kit. They stopped selling it a few years ago and the Tanaka parts guy doesn't know where they bought those parts.

    There is still a fuel leak but now I don't know where it is from. It is coming from somewhere around the place around the carburetor. The leak is so slow that I can't find a drip point. I just see dirty oily streaks on the gas tank.

    I didn't know about this leak until the other ones were sealed. Do carburetors actually leak around the spot where they mount to the motor? How could such a tiny motor with such low compression blow a seal? I'm going to keep cleaning the area looking for the origin of the leak. Eventually I'll find it.

    If it is a gasket are there any reliable gasket repair products? I see them in parts stores but I've always wondered if they really work.
     
  11. GearNut

    GearNut Active Member

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    I recommend replacing a bad gasket before repairing it.
    The best gasket dressing I have ever had the pleasure of using is Hylomar.
    You can buy a cheap copy of it made by PermaTex in most automotive parts stores. To get the real stuff you need to find an aircraft parts and repair shop or on line vendor.
    Aircraft Spruce is a good one.
    I am sorry to hear that SealAll has failed you. I have never used it on a plastic gas tank.
     

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