68 American Eagle GT has a fuel tank leak

angonemoto

angonemoto

Hero member
Location
Chicago, USA
Hi all,
Very small hole or holes making a huge mess on the bottom of the tank, not at the seam, right above the petcock.
Is there any way this can be fixed from the outside? The inside of the tank is very clean and clear of rust, I want to try to keep from using the usual tank liner stuff if I can avoid it. See pic. It was pissing out gas so I am glad I wasn't riding it when this happened. See what I get for replacing the fuel lines and some other maintenance? I thought that bent fuel filter was the culprit, but it surely wasn't. Someone had been here before me from the looks of the leaking area and the way the paint came off with my finger.

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Hey Bob ,I have used fuel resistant epoxy before with good results,of course its all in the prep,the stuff was a two part epoxy called metalox, I don't even know if they make it anymore,but has to be something out there that will work. 
 
I reckon any epoxy will do. Most of the common epoxy resins use similar chemistry (reacting epichlorohydrin with Bisphenol A) and the resulting polymer is fuel resistant. It's also heat resistant (up to a point) so it won't be bothered by the hot engine sitting just below it.

If it's only a tiny pinhole, you probably don't need anything with a filler in it like JB weld or epoxy putty. I reckon you'd be better off using a more liquid product that will be drawn into the hole by capillary action. A smear of Araldite over the area of the pinhole would probably do the trick. Give it a rub with sandpaper to provide a "key" for the epoxy then wash it with thoroughly with thinners or acetone to remove any remaining gasoline before applying the epoxy. When the epoxy has hardened, you can sand and paint it.

I believe Grant was a plastics chemist in a previous life. He'd probably have better knowledge about epoxies than most of us dimwits.
 
I have a couple of oil leak issues from my bike head, I used a Defcon malleable high heat resistant epoxy putty after thoroughly cleaning it and giving it a sand. Was very happy to see it work, for about a week. Seems the oil eventually seeps through even with it 5mm thick. I have heard stories of using this product to fix damaged crankcases and sumps, not for me. Anyone found an oil resistant epoxy that works on Aluminium and is 100% oil resistant.
 
Bob, to reiterate Cam. Make certain it is clean of fuel so the epoxy sticks. I used JB Weld to seal a hole in a remote float dellorto bowl with no problem but it isn't tidy.

Vince, there may be an issue with the expansion and contraction of the alloy keeping the Defcon from maintaining a seal. It may also be the porous casting contains enough oil residue it can't be cleaned enough for the epoxy to stay attached. I have seen epoxy make oil tight seals in the strangest places from a holed oil pan to a holed engine case.
 
Thanks all. I shook most of the gas out yesterday and am off to get some acetone this morning to dry it out more. Should I pull the petcocks for the acetone rinse phase? I imagine the filters will hold some liquid that won't shake out and could spoil my efforts.
 
If possible I would have it welded/lead loaded and then use an epoxy sealant on the inside of the tank.
Trouble is sometimes there's more than one hole if you strip it all back.

 
angonemoto said:
Thanks all. I shook most of the gas out yesterday and am off to get some acetone this morning to dry it out more. Should I pull the petcocks for the acetone rinse phase? I imagine the filters will hold some liquid that won't shake out and could spoil my efforts.
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The filters could well melt with the acetone.
Paul
 
Thanks for all the advice. I now can confirm there is already a layer of POR15 in the tank that has failed to stop the tank from deteriorating, thus my pinhole leak. Can I prep the interior of the tank and re coat it? I really like Grants idea of welding leading, but I wonder what that will do to the POR15 that is on the inside of the tank already. Back to Google...
 
Worked for me on another bike I had with a pin hole leak.-

http://www.ebay.co.uk/itm/Brand-New-Plastic-Padding-Leak-Fix-Mini-/332200953806?hash=item4d58b847ce:g:baQAAOSwPe1T4gVA
 
Latest advice from a trusted bike restorer is for a temporary fix to solder up the hole and deal with a more permanent fix in the off season.
Here is a link to the leak. You can see the other exterior fix attempts to the left of the leak.

https://youtu.be/a8cOiI518VM
 
I have had a couple of old gas tanks leak and after a while I felt I was chasing a rabbit down a hole. On my 72 Guzzi Eldorado I eventually stripped the tank and found it was more holes than solid steel, I tried rebuilding the bottom of the tank but that didn't go well, I eventually found a better tank.

I would recommend you strip the inside of the gas tank of all the liner and the rust the liner is probably covering. Personally I don't think much of covering a rusted tank interior with any sealer and I have tried several.

My new go-to product is Evaporust, I bought 8 galloons of it and every gas tank I has been removed from the bike, petcocks removed, petcock bungs plugged and then I fill the tank right to the top until it overflows then fit the gas cap on tight. I let it site for at least three weeks occasionally shaking the tank. Every tank I had that was flaking rust or worse comes out spotless. I rinse with methylhydrate as the Evaporust is water based. If the tank has holes you will need to temporarily plug them

My Laverda SF1 tank had good original paint but a lot of rust inside, here its is soaking away until the interior looked like new.



With the rust out of the tank you probably won't need a liner unless you have some pin holes and don't want to repair and repaint.

I currently have a 74 Benelli Tornado gas tank into its 3rd week of soaking, The inside was full of all kinds of crap including rust, dead insects, plant seeds and what looked like a mouse skeleton.

The Evaporust will not harm the paint.


 
angonemoto said:
Excellent. Will the evaporust remove the POR 15 liner material? Or does that require another approach?
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Acetone should dissolve POR-15 gas tank liner.
I have a Moto Morini gas tank that the previous owner coated right over the rust. Its a real crappy job and I need to get the liner out and then get the rust out! I really don't understand why people line gas tank, if the liner is going over rust it just traps the rust between the metal tank and the non-breathable liner and this will just accelerate the rusting out of the tank.

I don't think anyone would recommend painting over a rusted body panel so I don't understand the logic the tank sealer manufacturers are using in selling these products.

 
I agree with all of this, but also know folks who have successfully lined their tanks without issue. Like most things of this sort, the preparation is the critical issue. I am not a fan of tank linings that are the pour in type. I am interested in welding and tinning the inside tho. I will keep follow ups to this as I go down the road to a more permanent fix.
 
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