Pinhole leak in gas tank

onetruepunk87

onetruepunk87

Been Around the Block
I posted this in my '77 CB750K build thread as well but thought I might get more answers here...


Out of nowhere I seemed to have developed a pinhole leak in my gas tank. So.... anyone have any thoughts on what's the best way to fix this? The leak is incredibly small. It's just above the carbs on the left hand side of the gas tank just above the bottom seem of the tank. The hole is just a dot in the center of the small circle where the paint is completely gone.

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Should I try my luck with a tank liner like Red Kote or POR 15 while the hole is still tiny or attempt to braze the spot and hope it doesn't make it worse?


Any help is appreciated.
 
I had several pin holes in my gas tank so I got a can of Red Kote from Dime City Cycles and lined my tank. It worked like a charm, would highly recommend it! :)
 
A small pinhome os often the first sign of a more serious issue. Random pinholes don't generally juwt form out of the blue. Its likely that you have a larger rust or corrosion issue hidden under the paint.
 
Von Yinzer is sort of in the right direction in his post, though I would say it is not rust under the paint, but rust inside the gas tank. This is just the first pinhole. There will likely be many more in short order.

You have to do the whole routine with internal rust removal, etching, and sealing. I like the POR15 system very much, but its ability to seal an actual leak is pretty limited. The Redcoat system would probably be better in your case, because it is a thicker product that would be better at bridging pinholes.

When you are doing the rust removal, throw a handful of nuts in there and shake them around. That will help to knock off some of the worst rust so that the rust remover can get you down to bare metal. You may find, after you have removed the rust, that you have a lot more leaks!
 
That's what I was afraid of. The bike had been in storage for a decade before I bought it, I'm guessing some moisture got it in the tank and went to town. I had it on the center stand for the better part of this past month in my garage, I moved it yesterday and had it on it's kickstand for abou 20 mins and then I noticed the paint bubbled up.

Any ideas for fixing it or should I add a new tank to my list of things to get?
 
Pull it and drain it. Clean the inside as Alpha said. Seal it.

Or send it out to have it done professionally.

Or find a new tank. Those are the options. With the first two, you'll likely end up having to repaint so keep that in mind.
 
Thanks AlphaDog that was kinda what I planned just wanted to make sure I was on the right track. Any suggestions on what to clean the tank rust out with? I read 50/50 CLR and water somewhere.
 
Thank you too, VonYinzer! I'm gonna try and clean it out real good and see how many other leaks develop from that and try coating it. If it doesn't work I'm not out that much money. Thanks Bert, I'll keep my eye out for another tank just in case.
 
Thanks Jkimtkd too for the recommendation, didn't mean to leave you out! Gotta love all the help in this place. Happy Easter to anyone who celebrates or just likes eating chocolate and ham.
 
You can get those tanks fairly cheap on ebay (or some similar site) Just have to keep a look out, you'll see a lot of them way overpriced before there's one for a decent amount. Just an option. Otherwise, I'd go with the options already stated, clean it and seal it. Rust will spread quickly once it starts eating base metal.
 
Hopefully the Red Kote will do the trick, at least for the time being. I'll be checking ebay/craigslist periodically for a tank. Down the road I want to do a paint job on the bike (I had really good results doing a rattle can job on my CM400) and with all of the prep work that goes into that I don't want a tiny hole fouling it up.

I'll let everyone know how it works out. I'll try and take some pics along the way and maybe I can put up a tutorial/review when I'm done to help out the next person this happens to.
 
Clean it, dimple and solder the holes (use plumbing solder) and sand smooth, pressure test it (air and soapy water solution), if it passes clean it again, red-kote or similar heat cured liner, body work it (you did dimple the hole before soldering to ensure a good patch, right) and paint it. Por-15 is good stuff, but you need to solder any and all holes before using it.
 
onetruepunk87 said:
Any suggestions on what to clean the tank rust out with?
Click to expand...

Most any tank liner has a kit or system for removing rust and etching the tank prior to coating it. Follow their instructions explicitly. Proper prep is EVERYthing. If you short cut the prep, you would be better off spending that money on a lap dance, because your tank liner will fail, the rust will return, and you will have a mess on your hands.
 
Get a rubber or silicone plug from the drawers at lowes or Home Depot.
Works better than duct tape ;)
 
You can take it to a good radiator repair shop locally. They will seal it all up perfect and you probably wont have any issues as long as you're alive... I've "repaired" some small pinholes in a pinch with jb weld but that is just bandaiding the problem until you can fix it correctly.
 
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