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Author Topic: Small paint bubble, but no sign of gas leaking (smell, feel)  (Read 1876 times)

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Offline drumstyx

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Small paint bubble, but no sign of gas leaking (smell, feel)
« on: July 30, 2017, 08:38:50 AM »
After having my tank beautifully repainted, of course I drop the bike and get a big ol' dent and huge scratches. Well, I felt bad until I saw a bubble at the seam, so I figure I needed it repainted anyway.

Thing is, as far as I can tell, there's no sign of a leak under the bubble after scratched it away. It's clean metal under there, no yellowing, no smell, no feel of gasoline, and certainly no visible pinhole. I want to braze/solder any holes to avoid lining, but this is basically invisible.

So is it maybe possible there's a hole/porosity so small that you can't see it, but an extremely small amount of vapours get through?

I have the Caswell kit, but when I saw how clean everything came out, and I couldn't find any pinholes, I decided against it...do I have to backtrack and line it after all?
« Last Edit: July 30, 2017, 08:58:47 AM by drumstyx »
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Offline drumstyx

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #1 on: July 30, 2017, 08:59:32 AM »
Looks like maybe I could see where it might be more porous. Certainly no feel of anything coming out though, and the tank is full right now...

Bottom line is id hate to try and fix this, only to have the paint fail again...it's at least $300 each time I'd have to do it
« Last Edit: July 30, 2017, 09:42:38 AM by drumstyx »
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Online jgger

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #2 on: July 30, 2017, 10:15:55 AM »
Take it to a radiator shop and maybe they could pressure test it, then you would know for sure.
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Online PeWe

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #3 on: July 30, 2017, 11:23:10 AM »
Time for a tank sealer kit?
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Offline nvr2old

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #4 on: July 30, 2017, 11:53:09 AM »
It never hurts to have it pressure tested at a radiator shop.  They can seal it for you, too.   That's a spot on your tank, right in a crease, where maybe it just didn't get scratched up enough during the sanding process, and simply didn't adhere.  It certainly looks clean under there..hmm.
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Offline drumstyx

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #5 on: July 30, 2017, 12:06:14 PM »
Quote from: nvr2old on July 30, 2017, 11:53:09 AM
It never hurts to have it pressure tested at a radiator shop.  They can seal it for you, too.   That's a spot on your tank, right in a crease, where maybe it just didn't get scratched up enough during the sanding process, and simply didn't adhere.  It certainly looks clean under there..hmm.

That's what I thought!

Shops in Canada are nothing like shops in the USA -- you'd think people would be willing to take on a challenge, but here, the minute something is remotely unfamiliar businesses tend to just say 'nope' and leave you hanging. That is to say, finding a radiator shop that is willing is going to be a challenge (but unlike them, I don't shy away from one). Fixing things is also a lost art, so a lot of shops don't even have dip tanks anymore, but I digress.

Sealing was something I was considering months ago, just before it was painted, but it seemed fine, and I got all the rust out of the tank (metal rescue is awesome) so I figured I'd be fine. The Caswell sealer kit I have is supposed to be extremely good, but with as good as it is, there's always the chance that it fails, and then the extreme adhesion and resistance properties mean I'd have no chance of getting it all back off if I needed to. As such, it's a last resort.
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Offline TwoTired

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #6 on: July 30, 2017, 12:21:39 PM »
If you pin prick the paint bubble and it then leaks gas....
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #7 on: July 30, 2017, 01:05:28 PM »
+1. Wait for a leak.
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Offline Garage_guy_chris

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #8 on: July 30, 2017, 09:37:56 PM »
you can pressure test it yourself pretty easy go to a pool store and get a big expandable pool plug that fits the filler hole. then you can pressure it through the petcock, just keep the pressure very low like 5psi or under, any more and you risk deforming the tank!!!


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Offline go_hercules

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #9 on: July 31, 2017, 10:05:29 AM »
I have dealt with a lot of fiberglass tanks with leaks that bubbled paint.  I could ALWAYS feel and SMELL gas at the bubble.  I think your bubble is a paint flaw rather than a gas leak.  Like was mentioned above, possibly moisture or contamination on or under the primer.
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Online jgger

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #10 on: July 31, 2017, 07:13:52 PM »
Duct tape, shop vac, and the bath tub.

Tape the shop vac hose to the filler neck, close off the petcock (no gas in the tank, of course) and dunk it in the bath tub full of water with the shop vac running on blow. If you get bubbles then you have a hole. If not then yer good to go!
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Offline evanphi

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #11 on: August 02, 2017, 08:18:01 AM »
Quote from: jgger on July 31, 2017, 07:13:52 PM
Duct tape, shop vac, and the bath tub.

Tape the shop vac hose to the filler neck, close off the petcock (no gas in the tank, of course) and dunk it in the bath tub full of water with the shop vac running on blow. If you get bubbles then you have a hole. If not then yer good to go!

Oh man my wife is gonna be pissed when I try this. ;D

Kids will love it though.
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Online jgger

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #12 on: August 02, 2017, 08:00:50 PM »
Quote from: evanphi on August 02, 2017, 08:18:01 AM
Quote from: jgger on July 31, 2017, 07:13:52 PM
Duct tape, shop vac, and the bath tub.

Tape the shop vac hose to the filler neck, close off the petcock (no gas in the tank, of course) and dunk it in the bath tub full of water with the shop vac running on blow. If you get bubbles then you have a hole. If not then yer good to go!

Oh man my wife is gonna be pissed when I try this. ;D

Kids will love it though.

Just tell her how much money you will be saving on a tank liner kit! ;D Or save enough duct tape so you don't have to listen to it! The options are endless. :-X
« Last Edit: August 02, 2017, 08:03:16 PM by jgger »
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The difference between an ass kisser and brown noser is merely depth perception.  Stolen from RAFster122s

Offline drumstyx

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Re: Small paint bubble, but no sign of gas leaking (smell, feel)
« Reply #13 on: August 03, 2017, 08:20:34 AM »
What's the fuel cap vent pressure? Could I just set my compressor's regulator to a few PSI, cap the tank, hook up the air to the petcock bung and use some soapy water?
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