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  1. #1
    Jim Caudill is offline Stainless
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    Default OT: Best way to clean an old gas tank?

    We all have occasionally needed to clean a gas tank that has been sitting for a number of years. I recently acquired an old vintage scooter (Salsbury Model 85) and am going to send the tank and body out for chemical stripping. Will this clean the inside of the tank sufficiently or do I need to perform some exotic "solvent wash" with acetone, carb cleaner, or some other kind of "magic potion"? We always call the crud inside a tank "varnish", so I'm kind of thinking the paint stripper may do the job. What about rust inside the tank (assuming there is always some)? Finally, when I get it back, should I use a "slosh sealer" to coat the inside? Any product reccomendations?

    It seems like it would be a good idea to collect as much knowledge as possible regarding this issue, and have it stored in one thread, where it can be "searched".

    Thanks for your input.

  2. #2
    karl is offline Aluminum
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    I took an old Honda CB77 tank to a radiator shop for cleaning and then used a POR 15 product with no leaks in 8 years. If you have a general aviation repair in your area ask them, pilots take a dim view of loosing power while aloft.
    Karl

  3. #3
    Jeff_M_PA is offline Cast Iron
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    I've used two products for this: Red-Kote and Kreem. Seemed to work about the same. It's a rubbery polymer coating. They sell kits to do the whole job, clean, etch, coat. For a severely rusted Ford 8N tank, I rigged up a rocking device to rock the tank back and forth for a few hours with nuts and bolts in it to knock off the rust first. For motorcycle tanks, I've not had to do that. Just follow the directions; works great.

  4. #4
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    dbc58 is offline Cast Iron
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    I cleaned a tank for my ‘82 Virago with muriatic acid. It was full of flaking rust. I was planning on using Kreem to seal it afterwards but it wasn't needed. I was amazed how clean it came out in about 15 minutes. I used a rubber stopper for the inlet and fabricated caps for the outlets so I could rotate it to cover all of the tank. Had to leave one cap at a time loose due to pressurization. Do this out of doors - the fumes (visible) are potent and caustic. You don't want to breathe them. Rinsed repeatedly and neutralized with baking soda, final rinse with alcohol and dried with a heat gun. No rust - no leaks. There are a lot of warnings about muriatic acid causing leaks, but the way I look at it any leak it would cause would just appear eventually. Don't allow the acid to contact aluminum parts.

  5. #5
    jim rozen is offline Diamond
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    One way to do this is to put a cupfull or two of old nuts and bolts in the tank,
    tape it inside of a couple of pillows, and put it through your dryer on 'air fluff.'

    Not responsible for damages incurred when the SO finds out about this.

    Jim

  6. #6
    Punkinhead is online now Aluminum
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    Quote Originally Posted by jim rozen View Post
    One way to do this is to put a cupfull or two of old nuts and bolts in the tank,
    tape it inside of a couple of pillows, and put it through your dryer on 'air fluff.'
    Careful doing this. Many tanks have internal lips and baffles that make it a bear to get all the hardware back out. I know this from having a vintage roadracing bike with a nut rolling around in the tank for a couple years after using this trick for derusting.

  7. #7
    kevin johnson's Avatar
    kevin johnson is offline Cast Iron
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    I will second the Kreem. I have an old tractor that I coated the tank 20 years ago and it is still good.

    Dang I must be geting old.

  8. #8
    Jim Williams is offline Hot Rolled
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    I have the same problem. I bought my Model 85 Salsbury new in 1947. (It was out of my hands for about 40 years). The tank is full of pin holes which rusted from the inside. I recently learned that the Salsbury tanks were not plated or painted on the inside, and are frequenrly badly rusted. I am currently planning a good cleaning followed by one of the polymer tank sealers. Are you a member of the Salsbury Restorer"s Society?

    Jim Williams

  9. #9
    Jim Caudill is offline Stainless
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    Yes, I am member # 259 of the SRS and have a '47 sn 7419 and a '49 that I am trying to completely decypher the sn. I think is is 14071.

    Jim, I see you are member #70 in the register. Do you ever come up to Portland?

  10. #10
    Frederick Harvie is offline Stainless
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    I would be tempted to try The electrolitic rust method. Fill the tank with the electolight and make a suitably shaped bar that can be inserted through the fill hole for an anode. attache leads to anode and use take itself for cathode . I have not done this but it should do a good job.

  11. #11
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    W_Higgins is offline Hot Rolled
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    I do a few a year by steam cleaning and no sealer. Quite often, a lot of tanks still have a large percentage of their original plating intact and sealer is just something to fail later in life and have to clean out again. Sealer doesn't stop old gas from gunking up, which is the usual cause of undesirable content in old tanks. That, and foreign matter being introduced at the pump.

  12. #12
    MwTech Inc is offline Stainless
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    I'm a stone man

    close up the holes, add stones and strong cleaner and shake well

  13. #13
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    Mud is offline Diamond
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    I've cleaned a few, MC, car, tractor etc. I've settled on POR15's Marine Clean to get the varnish and gunk out, Evapo Rust to get the rust out, and POR15's tank sealer to seal it afterward if the tern plate coating is gone. I've used Kreem, and other MC coatings, and they seem to flow for quite a while after they dry, sometimes into the fuel line or petcock. The POR15 coating is silver in color and hasn't failed or leaked unless the tank split somewhere afterward. Marine clean is an extremely strong cleaner, but not as hazardous as acids.

    If you have a thin rusted section of pinholes, leading can sometimes do a good job of sealing that up if you don't want to weld in new sections. If you don't want to buy the supplies and tools and learn how to lead etc, sometimes a radiator shop can do that for you

  14. #14
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    JunkyardJ is offline Titanium
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    Arrow Did my CB750 tank with kreem a couple years ago.

    I coated the inside of my CB750 gas tank with kreem a couple years ago. First I rinsed it out with water, then took a bunch of BBs (yes for a BB gun) and put them in the tank with water. Shook the heck out of it for a while, dumped the BBs, rinsed and repeated until I was satisfied it was clean. Then I took a mix of this stuff called concrete cleaner (phosphoric acid) they sell @ home depot, mixed it 50/50 with water, and poured it in the tank for the night. Kept flipping it over and whatnot so it would kill all the rust. Rinsed it out real good one last time, and put my shop light under it to dry it out. Then I just dumped enough kreem in there to coat it real good, and kept rolling it around until I had a nice white coating in there. Still looks good, and haven't had any of it come off in the screen on the petcock.

  15. #15
    Newman109 is offline Titanium
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    I use phosphoric acid to clean motorcycle fuel tanks. I buy it in 70% and dilute it to about a 20% solution. I get it from a chemical supply for around $20 per gallon. It will remove the rust. I sometimes close the tank with a handful of nuts and bolts. It will leave a nice dark gray patina. If the tank has no leaks, you usually won't need to do anything else.

    It helps to keep the tanks full to keep corrosion from starting again.

    I've tried Kreem with poor results. It usually chips off after a year or two. I understand that POR is better.
    Last edited by Newman109; 05-03-2010 at 06:05 AM.

  16. #16
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    Sander is offline Hot Rolled
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    Most if not all of us know this already but I'm posting it anyway...

    Even after a vigorous cleaning please use EXTREME care when welding on a gas tank. 12 years ago I lost a friend who tried to patch a tank via welding. Took him, the car he was working on, the garage and the house out via epic inferno of flaming burn.

    Tank exploded, something touched off the rest of the "stuff" in the garage and the results made the news.

    There are ways to do it safely involving inert gas, tank stuffing and various other means.

  17. #17
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    Forestgnome is offline Stainless
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    Quote Originally Posted by jim rozen View Post
    One way to do this is to put a cupfull or two of old nuts and bolts in the tank,
    tape it inside of a couple of pillows, and put it through your dryer on 'air fluff.'

    Not responsible for damages incurred when the SO finds out about this.

    Jim
    Nice!!!!!!!

  18. #18
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    windmillman is offline Aluminum
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    Send it to the hot dip galvanizer. It gets boiled in hot muriatic acid first and comes out clean, looks new and is very well sealed. Good, fast, cheap.

    Tom

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