Motorcycle gas tank soldering...

[Doofy]

After reviving the wifes Honda ATC200 3-wheeler and getting it all ready to sell, I smelled gas and discovered a pinhole leak in the steel gas tank. I emptied the tank, let all the residue evaporate in the sun and flushed the tank several times with hot, soapy water. I then used a heat gun to evaporate all the moisture from the tank.

I do not use a flame or advocate using any flame for soldering a gas tank. The risk is just to high for having an explosion. Yes, there are the common tricks of routing a cars exhaust in to the tank or of using dry ice in the tank to displace all the oxygen to prevent an explosion but they are quite the hassle.

I generally use an ancient 300 watt soldering iron but today I couldn't remember where I stored it away... I did find a 105 watt soldering gun so I figured I'd give her a try. I sanded the paint off the area to be patched and cleaned the area with metal prep solvent.

Using a good paste type flux and acid core solder I went to work...BUMMER! Damn thing wouldn't get hot enough for the solder to flow. IDEA! Dragged over the heat gun and pre-heated the patch area and the solder flowed like hot butter. The tank was saved and I didn't kill myself.

Caswell has a new 2- part epoxy gas tank liquid tank sealer that I also plan on using to mitigate the rust in the tank. Tis a tad rusty since 1981. HaHa!

Hope this brief tutorial helps someone else at some point in time. Be Safe!

 

[alwaysFlOoReD]

Thanks, I'll use that someday.

 

[Doofy]

As a footnote...found several more pinholes in the tank today. Sanded, cleaned and soldered 4 more holes in about 15 minutes. This technique only damages the paint where it is sanded to make the repair. I spent an additional 10 minutes priming and touching up the areas.

 

[AllanD]

A couple of ideas on removing rust for you...

I restore a lot of Coleman lamps and stoves...

What I use to remove rust is Acetic Acid (vinegar)

However as a note ANY of the "Organic acids" are good rust removers because they are all powerful andi-Oxidants

I have personally tried:
Acetic acid (Vinegar)
Malic acid
Citric acid
Oxalic acid ("BarKeepers friend" cleaner)
All of these acids are "safe" for an overnight or even weekend long soak

Another acid that is reasonable effective is Muriatic Acid (AKA Hydrochloric Acid)
but you should not soak anything for any length of time don't leave items unattended
in this acid.
This acid turns a virulent yellow color as it breaks down rust and it gradually turns to a solution of Ferric (2) Chloride which is itself still very corrosive to Copper or Nickel based alloys, so keep it away from stainless steel or brass.

But HCl is good for a quick rust removing rinse for an unplated tank. but be SURE the tank is really Unplated, HCl reacts violently with Zinc.

 

[Doofy]

Thanks AllanD. It'll give the acetic acid a try.

 

[85_Ranger4x4]

They make a plastic fuel tank lining/coating you can put inside the tank to help prevent more holes from popping up. You just slosh it around in the tank so long and it works pretty good, no mixing or anything.

Get it good an clean inside first, available at parts stores.

I have had it in one of my tractor fuel tanks for 15 years, still working great.

 

[AllanD]

Thanks AllanD. It'll give the acetic acid a try.

What I personally use is a mixture of Acetic acid, Malic acid and Lactic acid, it is not a precise mixture
as it wasn't something I made intentionally



It came about from making a large batch of hard cider that I mostly transferred to another container
and the 15gallons that were left "spoiled" making a batch of homemade vinegar. I couldn't use it for
anything else because it smells like boiled athletic socks.

but the shit strips rust like a sandblaster...

it is all an interesting practical study in chemistry and micro-biology.
the apples naturally have sugar and malic acid
Yeast converts the sugar to ethanol and carbon dioxide in nearly equal proportion.

Acetic acid bacteria convert Ethanol and sugar to acetic acid.

Malo-lactic bacteria convert Malic acid and sugar to more Carbon Dioxide and Lactic Acid

All these bacterial reactions consume oxygen so you wind up with a vat of acid
that is oxygen free and want more oxygen and these chemicals want oxygen so aggressively they will "steal" it from rust...


In a 1/3 full 60-gallon container this acid bath sits under a protective "blanket" of carbon dioxide which stays in place because CO2 is approximately 1.5 times heavier than air (1.47 times if you like exact)

*******************************************************

If you want "Fast" use Hydrochloric Acid it often removes rust down to bare metal (often while you watch)... and aslong as you have some place to wash your hands nearby you can get it on your hands...


Hydrochloric acid sounds dangerous, but remember this is the primary acid in your stomach. and in dilute form it is the primary ingredient in eye drops.

But you probably should use eye protection and gloves and wear clothes you don't care about...

AD

 

[Doofy]

That was a very fine and interesting chemistry lesson AllanD. Made me thirsty talking about that hard cider, though. HaHa. I remember when I was about 16 I hid a jug of cranberry juice under my bed after adding some sugar and yeast. Evidently the rubber broke and the cat knocked it over...ate a big hole in the linoleum under the bed.