Repairing pinhole leaks in the tank

[KA1J]

I bought a tank last fall/winter and finally got around to putting it on and it leaked from a pinhole at the bottom at the back. It was supposed to be in good mechanical shape and that was wrong. I used aircraft remover to remove the paint from the area bottom and found maybe 20 little pinholes in clusters.

I'm thinking I should silver solder them shut, de-rust it and repaint, the outer tank looks fine. I'm wondering what kind of method I could use to do this best. I have a 250W soldering iron and a 125W equivalent butane torch. I could just JB weld the entire area and that would seal it tight.

Idears?

[Yard Dogg]

You could try a product called cream, or another tank lining product. Most of them come as a kit. It has stuff to remove the rust, then neutralizer, then you put the coating in. It may just plug the holes and bring back a little thickness. Maybe someone else will comment on it.

I had the same problem with my tank last year, I bought another. Don't bother trying to weld it, the metal is so thin from rusting it will probably burn through.

[Tat2demon]

I have seen a couple people talking lately about the Kreem liner coming loose. The Caswell epoxy liner has been sounding pretty good. I think I would try to solder or braze first then to the liner. JB weld may even work well as long as you do the liner also.

[jwhughes3]

I just sealed one with solder and alot of flux.

I used a propane powered soldering iron.

BTW: with soldering if you currently have a liner, plan on dissolving it and removing it.
Dry, empty tank.
Clean to bare metal.
Wipe with acetone or lacquer thinner.
Preheat area with propane torch.
Heat large (1/2") soldering iron.
Flux area generously.
Flow solder into and around holes. Some will drip thru, key is to get it to harden inside the hole.
Build solder in area and outward to allow you to sand back down smoother (dont sand too much!)
I think having a tiny depression around the pinhole helps, but the smaller the hole the easier to fill.
Add tank liner for extra protection.

Here is my finished hole.


John

[DGXSER]

I have not tried soldering on a tank. I have a tank that developed pin holes in several places when I used the electrolysis method of de-rusting. I go t the Caswell liner kit. I id not do anything to the holes except cover them in masking tape. That was in 2009, tank has never leaked a drop since. Liner is holding up perfectly.

[natemoen]

When soldering holes DO NOT USE LEADED SOLDER!!!!!!!!!!! When you sand the area down you will then be breathing the lead in.

So unless you have the proper equipment to capture and take care of the lead just don't use it.

[jetmechmarty]

If you're going to use a Caswell liner, no sense in messing with electrolysis or spending money. Just put diluted phosphoric acid in the tank, or fill it with vinegar, Coca-Cola, or whatever your favorite acid is. Caswell says leave the rust there, but I'm not one to do that.

Don't put gasoline in a Caswell lined tank until it cures completely.

[spayne83]

I just tried doing the whole de-rusting thing with Apple Cider Vinegar and then I went to "The Works" because there was still a bunch of rust in the tank. This really ate away all the rust but also opened up the pin holes to gaping holes, so be careful.

I ended up taking mine to a radiator shop and having them fix it. They also put a liner on it for me. I have this: http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1
that I bought before the rad shop if you are looking for an all in one solution.

[jwhughes3]

When soldering holes DO NOT USE LEADED SOLDER!!!!!!!!!!! When you sand the area down you will then be breathing the lead in.

So unless you have the proper equipment to capture and take care of the lead just don't use it.

Good point nate I did not cover. I used lead free general electrical solder with no core and external flux only.

John

[fredintoon]

- - - I'm thinking I should silver solder them shut, de-rust it and repaint, the outer tank looks fine. I'm wondering what kind of method I could use to do this best. I have a 250W soldering iron and a 125W equivalent butane torch. I could just JB weld the entire area and that would seal it tight.
Idears?

Hi KA1J,
"silver solder" (AKA low temperature brazing metal) needs an oxy-acetylene or oxy-propane flame to run it.
Plumber's solder (the modern lead free is safest but a mask will work for the old-fashioned stuff) will run with a Bernz torch or a massive soldering iron.
The secret is in the prep. It's the same prep for braze and for solder.
Sand the area squeaky clean.
Tap each dent with a centerpunch and light hammer to make a small dent so the solder has a pocket to sit in.
An automatic centerpunch might work good or if the tank is really rotten it might turn a pinhole into a REALLY BIG pinhole.
Slather the area with paste flux for solder or mix brazing flux powder with water in a stiff paste for brazing.
Torch the area and dab the metal on so it fills the dents.
Sand smooth.
If you choose to seal the tank (FYI, I've seen as many posts asking how to remove failed Kreem as I have posts on how to apply it, I'd say use something else)
NOW is the time, before the repaint.

[KA1J]

Sorry for this filler space, It looked like my post was hung so I tried again and double posted.

[KA1J]

Some really helpful replies and thanks. I'm thinking the weller soldering iron might be the best way to heat as it has one of those pencil thin high temp flames that can be exposed to the outside. What the flame runs into is a catalytic section and the heat from that is transferred to the soldering tip. I suspect the highly concentrated butane (hotter than propane) will be good to focus on one area and I'll try that first & see how it goes. Going to try that right now.

If it doesn't want to work I'm going to get some of the liquid JB weld or whatever epoxy it is that I coated a copper pipe in the house with that developed a crack. It's thin, light tanish/whitish colored and clings like crazy. It's been working for many years now on a pipe in the basement and still firmly attached to the pipe with no leaks. It would make a really solid base on the bottom of the tank regardless of whether the tank gets lined or not.

There is rust inside so I'm going to use evaporust to remove that, it won't etch into non-rusted metal. I'll tap around the rusty area (only at the lowest parts of the bottom where the water had concentrated & rusted.

Shame people put tanks away with gas and then leave them for years that way without having a stabilizer / enzyme treatment to keep the water dispersed. I use star tron and run the engine throughout the winter and slosh the tank for good measure to keep everything mixed.

We'll see how it goes...

[DGXSER]

I would highly suggest lining the tank if you go the JB Weld or similar route. A no longer very active member DBeardslee used JB Weld to fix his gas tank where the drain line had rotted out, back bottom of tank. Worked great for a while, then one day he was riding and felt a cool moist feeling in his crotch, looked down and it was as if he peed gasoline in his pants!!

That's when he went with the Caswell liner. YMMV