Cleaning rusty gas tank - anyone tried Metal Rescue Rust Remover? Other ideas?

[Zonda]

Oxalic acid is highly combustible and can even explode when mixed with certain oxidizing agents and silver compounds. It's also highly corrosive to skin. Phosphoric acid is a bit safer and does a better job converting severe rust.

I think you need to do a little research, any oxidant mixed in strong enough concentration is explosive and if used "as directed" is safe and problem free, in fact it is sold in many forms in shopping centres, one being a pipe cleaner and stain remover as well as a timber deck cleaner. As for Phosphoric acid being safer, they are both as toxic as each other and both are corrosive to skin. With Phosphoric acid being listed as a known carcinogen and having other health side effects.

 

[irk miller]

I think you need to do a little research, any oxidant in strong enough concentration is explosive and if used "as directed" is safe and problem free, in face it is sold in many forms in shopping centres, one being a pipe cleaner and stain remover as well as a timber deck cleaner. As for Phosphoric acid being safer, they are both as toxic as each other and both are corrosive to skin. With Phosphoric acid being listed as a known carcinogen and having other health side effects.

My research comes from their MSDS. And why are you being argumentative, yet supporting my comment about it's explosiveness? Yes, use as directed. I'm not going to apologize for pointing it out.

 

[Zonda]

My research comes from their MSDS. And why are you being argumentative, yet supporting my comment about it's explosiveness? Yes, use at directed. I'm not going to apologize for pointing it out.

Same here, but you stated that one corrosive acid was safer than another, very foolish considering they are both listed on the dangerous good register.

 

[irk miller]

Same here, but you stated that one corrosive acid was safer than another, very foolish considering they are both listed on the dangerous good register.

Not to go back and forth on this, but what I said was it is more corrosive to skin. Phosphoric is listed as a mild acid. Phosphoric converts rust to iron phosphate when the hydrogen bonds to the oxygen and leaves the good metal in tact. Iron phosphate prevents rust. That's a major advantage to the phosphoric acid. As long as water stays off the metal, it can prevent flash rust for years.


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[Jimbonaut]

Well, I'm kinda mashing up all the advice and seeing how I get on. On closer inspection (and I mean that figuratively - there's no way to closely inspect the inside of a CB750 tank, man that thing is convoluted) it looks like I have varnish build up in there too so first things first, get rid of that.

I emptied 8 litres of lacquer thinner in there last night, and loosed up whatever I could by throwing in 20ft of rough chain (with a piece of jewelry wire tied onto the end and coming out from under the tank cap for easy removal). 8 litres is not enough to fill the tank so I'm gonna move it around and see if I can't get that varnish to dissolve. Once I've done that I gotta get it all out, then clean it up, then attack the rust. Bought a couple of gallons of Metal Rescue (with the dude from American Pickers grinning all over it) and see how the mop flops.

Thanks guys, I'll keep you posted...

 

[firebane]

I took a look at mine again and after 5 days the liquid is pretty much a solid black which they say is when the product no longer works. I will probably have to pick up another jug to finish the tank off but from what I have seen it has worked well.

My biggest issue was finding a way to seal the tank opening without losing liquid which I accomplished but for the future a 2" rubber plumbing cap with a hose clamp should suffice.

 

[Jimbonaut]

5 days huh? You're a patient man, but you're right, no sense in rushing it. I'm hoping the rust situation isn't too bad in mine - the lacquer thinner is doing a number on the varnish and hopefully the rust is only superficial. Time will tell


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[iatethepeach]

there's no way to closely inspect the inside of a CB750 tank, man that thing is convoluted

You can get a cheap endoscope (for less than a gallon of Metal Rescue) that'll let you inspect your tank thoroughly.

 

[Jimbonaut]

Damn, you're right. I can fulfil two things at once - my childhood ambition of become a surgeon and seeing what lies out of view in my gas tank. Cheap at half the price


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[Trevor May]

Those products are not acids, they're called chelating agents, which sounds weird but apparently that's the magic. I looked up an explanation and I'm no less confused.

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[Perter]

I cleaned mine with household vinegar in about a week. It was pretty clean afterwards.

While the tank was filled with vinegar, I took around 20 M8 nuts and pulled a fishing line through so they were on a loose chain. Then I dropped it in the tank and did a good shake 2-3 times a day to remove hard rust/dirt

 

[Jimbonaut]

24hrs in and the lacquer thinner adventure is, well, it's pretty uneventful. Like watching paint dry. Or varnish dissolve. Sloooooow going - anyone done it and can tell me how long that shit takes to dissolve? I'm gonna leave it in over the weekend - if the varnish is still rubbery then it's decision time I guess - leave it in for longer of try something else.

Thanks again for all the input, may our tanks be clean and our carburetors happy

 

[firebane]

So I had to drain mine tonight as it wasn't working anymore. I will pick up two more jugs to do one more run and that should be good.

 

[Jimbonaut]

What I've learnt about de-varnishing and de-rusting '81 CB750 gas tanks so far...

1. More or less every step pretty much sucks balls
2. See 1
3. See 2
4. Don't use lacquer thinner to dissolve the varnish, totally didn't work. Softened it but that's it
5. Use MEK - that shit not only melted the varnish it melted my eyeballs and made inroads into my soul
6. With that in mind, handle MEK with a respirator (I did) and in a well ventilated area (I did. In -15 Celsius)
7. MEK will destroy petcock gaskets - no biggy as I'm replacing mine anyway. But know that, otherwise your garage floor will end up wearing some highly flammable shit
8. Be patient - I let the MEK sit in the tank for a few days, moving it around so it got everywhere. But I had a serious varnish situation happening
9. MEK (in Canadian Tire anyway) comes in small, 1 litre cans. I used 4. Don't do what I did, which is to try draining the used MEK back into separate cans. It's a highly combustible ball ache. Get a larger 5 litre can and drain it all in one go.
10. Once drained, chuck in a couple bottles of alcohol to mop everything up. Don't get impatient and try to speed up the drying process by blowing your shop vac in there. Like I did. And blew a bunch of shit/wire/crap into the tank. Big - and massively irritating - fail there.
11. Go the Metal Rescue, got 2 gallons of that mofo in the tank now and - if you're freezing your balls off in The Great White North - point your heater at the tank to keep things as warm as possible. Like all good things (except beer and snowball fights) it's better toasty.
12. Use a good length of chain (with a piece of thin wire coming out of the gas tank cap to make for easy removal) in the tank to knock off any big rust
13. Find something else to do while the whole thing does it thing - takes days. I've degreased the engine and frame, and now plan on starting a brewery.

Oh, and the whole process sucks balls

 

[firebane]

I discovered after day 6 rust held a few key parts of my tank together and unfortunately I am now looking for another tank.

 

[urastus]

Has anyone mentioned molasses? I thought it would be well known http://www.practicalmachinist.com/vb/general-archive/rust-removal-using-molasses-90452/ or just search for molasses and rust removal

 

[stroker crazy]

Has anyone mentioned molasses?

I've used molasses for rust removal and it is excellent (but slow)!

One part molasses to ten parts water (or thereabouts). Removes rust but doesn't touch the steel.
After draining the tank use methylated spirits to clean and dry.

Crazy

 

[hdscarbro]

The best alternative I've found that's like EvapoRust or Metal Rescue is Rust911. http://www.rust911.com/

It costs $60.00 for a gallon of concentrate that makes 16 gallons of solution.

 

[JiveTalkinRobot]

Evaporust...

Metal screws and bolts...wrapped it up in a blanket and stuck it in a dryer.