De-rusting the gas tank with vinegar

[Bminder]

While Randy is cleaning my carbs, I'm de-rusting the gas tank, which had rust spots in it. After doing some research about different methods and the costs, I decided to try using vinegar.  I've had it soaking in the tank for a few days and just poured it out. Amazing how clean it got it and how much rust came out. So I rinsed it out with water and then put a fresh batch of vinegar in it for a second go-round.
The nice thing was I could just wash it out on the driveway and it smells fresh and clean. 
It's probably not as fast as stronger acids, but if you have the time it's cheap and effective and not as messy for cleanup.

[fj11.5]

Nice find mate, I suppose it is a mild acid ,wonder if it would work on blocked carb parts 

[Bminder]

I dont' know, but it's a very mild acid, it would probably take forever if it worked at all.

[fj11.5]

True, could take forever 

[cm08]

I have Also used vinegar. It worked.  Filled tank and left it in for 2 days. Tank was nice and clean but it will rust again very quickly if not filled with fuel very soon after.

[Bminder]

Yeah, it flash-rusts immediately. After you drain the vinegar, you are supposed to rinse it out with water and baking soda to neutralize the acid. Then I'll coat the tank with oil before I put gas in it.

[Capn Ron]

I decided to try using vinegar. Amazing how clean it got it... So I rinsed it out with water and then put a fresh batch of vinegar in it for a second go-round. I could just wash it out on the driveway and it smells fresh and clean. 

What a douche...

[bigbore2]

White vinegar is acetic acid.  About a 5-8% concentration, ph is about 2.5 so it is not a mild solution. I was suprised to know how strong it is also. Muriatic acid [hydrochloric acid ] could be used also, found in hardware stores.  That sounds like a great way to do the cleaning.  Carb parts could be cleaned but because they are aluminum, not steel, will change the color to a dark grey.

[rktmanfj]

Phosphoric Acid will convert any rust (iron oxide) to ferric phosphate.

Here's the relevant part of the Wiki:

Rust removal[edit]
Phosphoric acid may be used as a "rust converter", by direct application to rusted iron, steel tools, or surfaces. The phosphoric acid converts reddish-brown iron(III) oxide, Fe2O3 (rust) to black ferric phosphate, FePO4.
"Rust converter" is sometimes a greenish liquid suitable for dipping (in the same sort of acid bath as is used for pickling metal), but it is more often formulated as a gel, commonly called "naval jelly". It is sometimes sold under other names, such as "rust remover" or "rust killer". As a thick gel, it may be applied to sloping, vertical, or even overhead surfaces.
After treatment, the black ferric phosphate coating can be scrubbed off, leaving a fresh metal surface. Multiple applications of phosphoric acid may be required to remove all rust. The black phosphate coating can also be left in place, where it will provide moderate further corrosion resistance (such protection is also provided by the superficially similar Parkerizing and blued electrochemical conversion coating processes).

[Bminder]

Like I said before, if you have the time, vinegar is a nice, cheap, somewhat environmentally friendly way to go.
And I like how I can rinse it out in the driveway.
Neighbors were driving by watching me rinse out this gas tank with the garden hose on the edge of the driveway and were thinking "What's that redneck idiot doing now?" 

[rktmanfj]

Like I said before, if you have the time, vinegar is a nice, cheap, somewhat environmentally friendly way to go.
And I like how I can rinse it out in the driveway.
Neighbors were driving by watching me rinse out this gas tank with the garden hose on the edge of the driveway and were thinking "What's that redneck idiot doing now?" 

Phosphoric costs about $10 more than vinegar, works faster, converts any rust present, is neutralized with water (just like vinegar).

Either will derust the metal.   

[jscgdunn]

So after you get the rust out, how do you stop it from immediately oxidizing?  Also, do you need a coating of any kind to line the tank after de-rusting?   In our 86 tank we have a mess  from one of the coating products; basically it did not stick.   
Any advice on what might work to get the mess out would be great.

Thanks,

Jeff

[fintip]

Those coating products are terrible. More people have ruined tanks with them than have saved them. And they are a bitch to remove, most people just give up.

Phosphoric acid is present in coca cola and what causes it to clean pennies. Betcha a gas tank of coca cola would do the trick.

[rktmanfj]

Phosphoric acid is present in coca cola and what causes it to clean pennies. Betcha a gas tank of coca cola would do the trick.

It also has a lot of sugar in it, which would have to be rinsed well.

[Bminder]

So after you get the rust out, how do you stop it from immediately oxidizing?  Also, do you need a coating of any kind to line the tank after de-rusting?   In our 86 tank we have a mess  from one of the coating products; basically it did not stick.   
Any advice on what might work to get the mess out would be great.

I can't help with getting the coating product mess out, but what I've read after using vinegar or any acid like that you should rinse the tank with a water/baking soda mixture to neutralize the acid.  Then put some oil, or Marvel Mystery Oil, or some oil product into the tank and swish it around to coat the inside.