Topic: tank cleaned with white vinegar, yes you read it right..

[13ill]

posted this in another thread but i felt it was important enough not to get buried on page three.

have a tank off my bmw r100gs that was full of old gas and rust. p.o. said the bike had sat with fuel in it for over three years. i've never seen a tank this nasty on the inside. tried acetone, didn't really get a lot out. then i read that white vinegar works.
yea, right. what the hell its cheap, lets see what happens. left two gallons of white vinegar in there for three days, looked inside the tank and it looked like the rust had gotten worse. i took it up to the power car wash blasted it out and.... holy toledo the vinegar worked awesome. i have five gallons in the tank now as a secound treatment to get all the rust that had built up on the sides too.
heres a crappy picture but look at the filler neck compared to the inside of the tank. the inside of the tank was about ten times worse....

[manjisann]

Interesting, and when you are done you can make a lovely vinagaretter with it 

It does beat using some of the caustic cleaners out there.

Brandon

[laser145]

I've done this a couple of times. The vinegar is effective and easy. Just be sure to move quickly to prevent flash rusting upon rinsing...it happens right before your eyes!

[Jerry Rxman Griffin aka MuthaF'er]

Mildly acidic - acetic acid.

[seaweb11]

uh-hu

http://forums.sohc4.net/index.php?topic=86179.0

[TwoTired]

Yes, any acid will work to remove rust.  It will also dissolve steel too, at a rate commensurate with its acidic strength.  (see a pH scale)  Molasses will "work", too. (Sulfuric acid).
Most of these suffer from flash rust (once the bare steel is exposed) formed by the reaction of iron and oxygen in the presence of water or air moisture.

From Wiki....
"Rust removal

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 (rust) to black ferric phosphate, FePO4.

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.)"

Cheers,

[Cut]

After much research, thought and deliberation, I too have decided to soak my 75' CB550 tank in Vinegar for a few days.  Wal-Fart sells 2qt bottles of "Cleaning Vinegar" in the household cleaner isle for $1.65 per two quart bottle.  At circa $8.00 all said and done, this is a great way to get'er done provided you have the time to do it properly.  The bottle did not say what the acidity content was though.  I'll post back in two days.

Petcock out!

[DarkLinkX5]

I did this to my tank except a used 1 gallon of white vinegar about a cup of muratic acid (for good measure) and filled the rest with high end garden hose water. 
let it sit overnight, drained it and rinsed with acetone then pored some Red Kote in the to seal it up and prevent flash rust and further rusting.
(i initially tried to zinc plate the inside but that was difficult and only plated a small area where i fed the zinc wire in.
also tried POR-15 and that failed spectacularly because i wanted to get rid of the rust not keep it in there... ) 

My tank had tons of pin holes that at first i tried to solder (got solder drops in the tank and had to remove... not recommended) and a nice grape size hole i patched with scrap and a welder.
I ended up using fiberglass to patch the bottom and on both lower sides for good measure. sanded, bondo, sanded, primed and sprayed plastic-kote on the unseen bottom area. its a gas/ scratch resistant bed liner paint.  it holds gas pretty well now.

still considering buying an eBay tank with less rust for long run use.