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Rust removal from inside gas tank

Discussion in 'The Garage' started by Frank The Tank, Sep 28, 2009.

  1. RatyXS

    RatyXS XS650 Junkie

    Just got some Caswell. Was going KBS but opted for the epoxy over the single app. I have used small dry wall screws, bb's in the past with good results to clean out flaky rust. However i do believe that the Caswell stuff adheres just as well to a rusted surface.
  2. ridgerunner1965

    ridgerunner1965 XS650 Addict

    a few years ago i had a yamaha tank i really needed to remove the rust from to get it running that day.i drug my old cement mixer out of the weeds, poured a couple handfulls of short drywall screws,a good handfull of bb's and a pint of diesel in it. wrapped it up in blankets and duct tape. jammed it into the cement mixer and plugged it in. every hour or so i would swap ends on it.

    after about 6 hrs i flushed it with soapy water and got everything out with a magnet.set it in the sun to dry out. put tank back on and rode that bike for several years. it seems the inside of the tank was so finely polished it resisted rust i guess.
  3. tadd442

    tadd442 dude.....

    So you used the Sta-bil to protect the metal from flash rusting, right? Have you put any gas in it yet? I am curious as to how the metal behaves once the Sta-bil has been washed off.
  4. I'm keeping it full of fuel. Doing just fine at 2+ months.

    Honestly I'll probably clean it out every year before bringing it out of storage. Simple, not messy, and had made this lightly rusted tank neatly brand new inside.
  5. Quinn_McLeod

    Quinn_McLeod XS650 Addict

    I've used the battery charger method, and it works well. But honestly, its still a mess to clean up. I had the easiest time cleaning out my rusty gas tank using BB's and WD-40.

    Guys use this method with spare nuts and bolts but they're hard to get back out of the tank once you're done with them. BB's are so small that they'll actually "drain" out our petcock hole as well as through the top.
    Furthermore, you don't need to duck tape a towel around your tank and put it in the dryer to get the rust off.
    I bought a package of 1000 Steel BB's and a can of WD-40. Cost me about $5. I plugged the petcock with a threaded bolt and after spraying the inside of the tank with a good amount of WD and inserting the 1000 BB's I closed the fill cap and shook the tank by hand. I did this for about 5 minutes and it made a HUDE difference. I emptied the tank of BB's and rinsed it with water. Then repeated the process. The result was a brand new inside to my tank. I did a rinse with gasoline, installed it on the bike and filled it up. Worked like a charm, less mess and clean up than the battery method and just as cheap.
  6. ThatXS650Guy

    ThatXS650Guy More Sparky than Speed Racer XS650.com Supporter

    Just got done with my Rusty tank and I am very impressed!

    I did the battery charger thing for about a week on and off. I changed the water and soap solution once and cleaned the sacrificial metal every couple of hours and then once a day. I also dropped a couple links of 530 chain and shook it around real good. After the electrolysis I use a gal. of Evapo rust and followed the directions. I finished it up with some diesel and motor oil as coating. I'll drain it all and fill it with fresh gas when I'm ready to install it.

    I can't believe how well this worked. The tank had sat with some fuel in it for over 20 years. The fuel had turned of course and the tank was a rusty mess. When I was done it was like new! One step closer to having the old girl on the road and all it cost me was $22 for the Evapo-rust which I can use again.
  7. Jpwhit1

    Jpwhit1 XS650 Enthusiast

    Just went through the process myself. I used Dawn soap and water and some "scrubbers". I then hit it with Jasco rust remover and metal prep. It's as clean as a whistle now. Keeping it full of of fuel in the ride season and empty and dry in the wet season will keep it happy.

  8. wah64apache

    wah64apache XS650 New Member

    Thanks yamaman. I just picked up a 75 XS650B that is completely stock short the mufflers. It has 11K miles on the odometer. Been sitting indoors near the Mississippi River. The tank is good on the outside but rusted badly on the inside. Based on your note I ordered MSR and Red-Kote off Amazon. Cheers, Frank
  9. PetesPonies

    PetesPonies XS650 Addict

    You just go to Home depot, buy some phosphoric acid for $15 and fill the tank with that. I use it often. It's cheap and it works. No need for another gimmick label, wasted money.
  10. abyssmaltailgate

    abyssmaltailgate Greenhorn Mechanic

    I'm partial to Yamaman's opinion on using MSR. I've done the sand/pebbles and water mix, vinegar, CLR, and even phosphoric/muriatic acid. I've had mixed results with CLR, but phosphoric/muriatic acid ALWAYS does the trick; however, I find it has many set backs...

    1) It eats through everything other than plastic/rubber, which can mess up more than just the finish on your tank...

    2) Since it is such a strong chemical reaction it can weaken the metal on your tank.

    I think what a lot of us are failing to recognize is that it is a CHEMICAL reaction so all that rust removal is happening on an atomic level, naked to the human eye. Sure we can see the metal becoming a shiny silver and that neon yellow acid turning rust brown, but the actual removal occurs when different atoms detach and attach to one another. Just because we empty our tanks of the acid bath and give them a rinse with water and oil doesn't mean the chemicals completely stop bonding and unbonding with one another.

    It's like when you grill steak a perfect medium rare; you've got a cooked outside with a pink inner perimeter and a big red center; however, once you remove that beautiful piece of meat from the grill, it's still hot and STILL cooking. The process doesn't magically suddenly stop. Let that steak sit for 15-20 minutes and you've got something closer to medium with an entirely pink inside, and that's not as juicy :shrug:

    What happens to the tank is that the acid keeps eating at the steel, which can weaken the overall integrity of the tank, bolt, springer, whatever your trying to restore.

    3) It flash rusts faster than shit through a goose

    In conclusion, YES, muriatic/phosphoric acid is awesome because it works quickly and gets the job done, but it is also hazardous and can be slightly overkill. I hope this helps guide some of your decisions!
  11. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Oh, you HAD to go there!

    That does it. Gotta pick up some steaks tomorrow.

    Maybe we need a Grill & Bar-B-Q thread...
  12. PetesPonies

    PetesPonies XS650 Addict

    Too much generalization here for scare tactics. I have been using phosphoric acid on restoration work for over 30 years. I first started by using DuPont's phosphoric acid. It is used as a etch, prior to spraying primer. This is a top notch refinishing company, seeing PA. I soon learned I didn't need to pay extra from them, but the benefits still are there. I have at least 100 vehicles on the road, with body restorations done by me using phosphoric acid as a pre-treatment, etch, before any primer was used. Should I start calling them all up and tell them there finish is going to fail because," the atoms" are still working? This is a bunch of crap. I have done many motorcycle tanks with PA inside, followed by either no coating, or a Master Series Silver coating. I imagine the first of those was 15-20 years ago I guess. I'm going to have to call him and tell him his tank is going to eat way. When I first started using PA, i called DupONT, because on a new can, their instructions had changed. I called and asked for R&D and low and behold, I was switched to that department. I spoke with an Engineer in R&D and had a great conversation. I was able to pass a few things on and he told me a few things. basically, the directions changed because some of the people where not using it correctly. He said he still used it according to the old directions and I said, so would I. You can'i idiot proof everything in this world, but when something works, I pass it on. 32 years of restoration work is from where I am speaking.
  13. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    30 years ago I used DuPont's PA pretreatment etch on my custom Vega. Today, with the exception of the gol-dang insidious rusting-from-within problem with Vega double panel sheet metal (rocker panel areas), the paint base coats are still intact.

    I've used Phosphoric Acid quite successfully on firearms. Of course, followed by generous rinsing and immediate oiling or bluing...
  14. tadd442

    tadd442 dude.....

    Doesn't PA need Oxygen to function?
  15. jetmechmarty

    jetmechmarty XS650 Guru Top Contributor

    I have no doubt you know what you're doing. I've used diluted phosphoric acid for derusting as well. Successfully, I might add. I put a baking soda mixture in the tank when I'm done, then dry it quickly.

    If the acid is too strong, or left to long, it can eat right through good metal. If not neutralized, it will keep eating. Just learn to do it properly before you give it a go.

    Electrolysis will do the job as well. It can lead to hydrogen embrittlement, I strongly suspect. I wouldn't use the method for anything structural.

    For a few rust spots in the tank, I like Metal Rescue or the other chelating agent whose name escapes me.
    Last edited: Dec 31, 2015
  16. abyssmaltailgate

    abyssmaltailgate Greenhorn Mechanic

    Jetmechmarty pretty much just summed everything I’m about to say very simply, but…

    Allow me to clarify and expand upon my last post. I’m not trying to “scare” anyone away from using phosphoric acid (PA). Like I said, it always does the trick when removing rust; however, it can be difficult to control if one doesn’t know what he’s doing. Chemical reactions like any other reaction involve the transfer of energy. In the case of removing rust with PA, the energy is eventually completely transferred from one state to the other. Continuing with my previous analogy, just like that steak eventually stops cooking once off the grill (even though it cooks for awhile longer), so will the P.A. eventually stop eating the rust and metal… that is if it is properly neutralized. I think neutralizing the reaction is the hardest part and can be difficult to guarantee, for this reason I decided to write a post in hopes of helping others so they don’t burn through a tank or have old spokes crack on the road. Pros who know what they’re doing should not have a problem using and controlling PA.
  17. Grimmith

    Grimmith Samurai

    Everything in these instructions were great and I'm currently doing it to my gas tank, I'm on my 4th time in 8 hour increments. It still has a little rust left on the inside but after watching it each refill, I see more and more shiny metal :D, its pretty much like "magic"
  18. cruzin

    cruzin XS650 Addict

    My son just removed the rust from inside his tank with red apple cider vinegar. But it is more expensive that baking soda and battery charger method.
  19. weekendrider

    weekendrider Iron Horse cowboy Top Contributor

    S.W. MO
    He would have found distilled white vinegar to be much cheaper.
    nj1639 likes this.

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