Tank cleaning advice

[WesV]

I decided to try the vinegar cleaning on my '82 850 tank and it worked like a charm, I left the vinegar sit in the tank for 4 or 5 days to really clean it out and after I dumped it out I realized that the flash rust was gonna be an issue so I went ahead and ordered a POR15 tank kit for it so when I went to work on it today I discovered that flash rust was MUCH worse than I anticipated. I had left the tank sit for about 2 week after I cleaned it till today when I went to coat it. It was so bad that when I went to rub a spot off the paint, my thumb went through the tank! Needless to say the smilies display my range of emotions because this tank was PERFECT on the outside and had been in storage, covered for 25 years.

When cleaning a tank be prepared to coat it or fill it up immediately!

[SqDancerLynn1]

It had to have a major rust problem before you started

[WesV]

It had to have a major rust problem before you started

Oh yeah, the inside was pretty bad, but I know the metal wasn't that soft when I finished cleaning it out but I also wonder if it wasn't from leaving the vinegar in there for so long, did the vinegar eat away at some of the clean metal... oh well no telling now.

[Nessism]

Lynn is right, the tank had structural damage from the storage rust, not the flash rust.

Not sure how strong the vinegar is. How about doing an experiment? Take a piece of sheet metal (measure it first with calipers) and then dunk it in the vinegar sauce for a few days and measure again. Report back with the results. I was going to try vinegar but now you have made me wonder.

[WesV]

I will give it a shot and report back this weekend on what happens.

[Adler]

I used vinegar with lovely results, and the 5$ price tag is certainly attractive. I doubt the weak acetic acid could eat through very much metal in that time, otherwise my salad bowls would look like swiss cheese.

[superdave]

**I have not personally done this**

The guy I bought my bike from suggested using Muriatic Acid to clean out the tank. He said it is usually available with swimming pool chemicals, and google revealed it is also used for a tile grout cleaner and concrete etcher. He said to dilute it 50% with water and leave it in the tank for about 20 minutes. I personally think I would first try a much shorter time and put it back in until satisfied if necessary...

I was thinking about the flash rust issue once a tank was de-rusted.

If you couldn't fill the tank and use it right away and didn't want to use POR-15, how about coating the inside with something else that would just mix with the gas and burn up eventually? I was thinking maybe a coating of 2 cycle oil, or maybe a bunch of WD-40 (though that would be hard to make sure it got everywhere). I think with 2 cycle oil, I'd probably thin it with some gas and put the mixture in the tank, and give it a good shaking. This would cover the inside with a bit of oil and should protect it. Then once you filled it up, the tiny amount of oil shouldn't hurt anything I don't think. If you were real worried, when ready to put the tank into use, you could rinse it with a bit of gas, and put that mixture in your weed eater.

Again, I haven't yet tried this, but I can't think of any reason it wouldn't work.

[Adler]

muriatic acid is annoying to use being that it is EXTREMELY illegal to just pour down the drain, also if it gets on you skin it wont be fun.
After doing my vinegar treatment i sprayed LOTS of WD40 in the tank, for those who dont know, the WD stands for water displacement, I havent checked recently but 3 days after the WD40 there was no rust.

EDIT: forgot to mention, after the vinegar i rinsed with acetone.... then WD40

[superdave]

Good point on the acid. I guess you'd have to take it to a hazardous waste place. The guy did mention that he saved it and was able to use it a bunch of times before disposal was necessary. He mentioned it was real handy for cleaning up rusty bolts and such too.

I guess WD40 isn't a bad idea, then.

[Nessism]

I'm not a chemist but my understanding is that muriatic acid is very strong and should be neutralized or it will continue to eat into the metal even if you rinse it off. I've also heard that it will eat rust and good metal at the same time. Phosphoric acid is more typically used by body shops since it chemically converts rust into a passive coating. Oxalic acid is good too - it is commonly used to eat off iron particle "rail dust" that attaches itself to automobiles that travel inside rail transportation cars.

Regardless of what method you use, sealing the metal is recommended after derusting otherwise you are at risk for the rust to return. I've used POR-15 tank sealer several times with good results, and there are several other good choices - such as redkote commonly used by radiator shops. Just stay clear of Kreem since the reported failure rate is quite high.

[Buffalo Bill]

Oops! Bummer…

As part of my tank cleaning process, I began by putting a handfull of nuts and bolts (up to 2"x3/8") into the tank and did the shaker dance. It was quite effective for taking off the heavy scale. I went on and used Evapo-Rust, for a few days with a handfull of 1/4" washers shook around a few times for help.
Tank's mostly clean with some rust left at the ends of the football.
The bummer is: I just noticed that the heavier bolts made little pips in the tank. Kinda looks like ostrich skin.
Don't ever shake large bolts in your tank!
Bill

[Nessism]

As part of my tank cleaning process, I began by putting a handfull of nuts and bolts (up to 2"x3/8") into the tank and did the shaker dance. It was quite effective for taking off the heavy scale. I went on and used Evapo-Rust, for a few days with a handfull of 1/4" washers shook around a few times for help.
Tank's mostly clean with some rust left at the ends of the football.
The bummer is: I just noticed that the heavier bolts made little pips in the tank. Kinda looks like ostrich skin.
Don't ever shake large bolts in your tank!
Bill

Aquarium rocks work great in my experience. They have rough edges so they scrub the metal well and their small size allows them to cover the entire tank area well.

[Billy Ricks]

Phosphoric acid is what you want to use. It doesn't harm to sound metal. If you treat the rust and don't intend to coat the tank or put it into service right away either fog it or use some motor oil in some naptha to slosh around in the tank. Dump the solution out and what's left of the naptha will evaporate and leave a light oil coating behind.

[Anggoro]

Have you ever tried washing the tank with coca cola? I have an old and rusty tank, is it true that coca cola can clean it?


And one more thing, is it true that washing with reverse osmosis water makes motorcycle paint not fade quickly? thanks

[Nessism]

Have you ever tried washing the tank with coca cola? I have an old and rusty tank, is it true that coca cola can clean it?


And one more thing, is it true that washing with reverse osmosis water makes motorcycle paint not fade quickly? thanks

Cola drinks have a very small amount of phosphoric acid in them so it's possible to derust LIGHTLY rusted items using it. For a rusted gas tank it would take a LONG time though.

And what kind of water you use to clean your bike has no affect on fading of materials after cleaning.