Author Topic: whats the best chemical to clean rust out of a gas tank  (Read 7685 times)

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Offline wizzy

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whats the best chemical to clean rust out of a gas tank
« on: January 17, 2008, 11:20:24 PM »
I have heard from a Local shop that using muratic acid could help assist in getting rid of rust in my tank. any one else use it before or should I try looking at another product.
the muratic acid I found in the hardware store states it is for etching concrete.
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Offline dkruitz

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Re: whats the best chemical to clean rust out of a gas tank
« Reply #1 on: January 17, 2008, 11:28:43 PM »
The folks at the antique outboard club have mentioned using muriatic acid for steel tanks too.
Be sure to rinse well and neutralize it with baking soda, use alcohol to remove the last of the water, then coat with a light oil such as 2-stroke oil to keep it from rusting.

Also, if you like less caustic solutions, try the arm and hammer washing soda electrolysis setup to remove the rust - widely documented on the web, but here are my notes:

Rust Removal via Electrolysis
Ingredients:
• Rusty steel gas tank
• Arm and Hammer WASHING SODA (from the laundry aisle at the grocery store)
• Water
• Sacrificial iron anode (large nail or piece of re bar, etc) - NOT stainless steel
• Automotive type battery charger (2 - 10 amp works well)
Steps:
• Dissolve 1 tablespoon (more or less) of washing soda per gallon of warm water required to fill the tank.
• Fill the tank with the solution.
• Affix the anode inside the tank so that it doesn't touch metal to metal anywhere. You can use scraps of wood and/or electrical tape on the ends, built up to insulate it so it won't touch the tank. You may extend it with a piece of copper wire outside the tank if needed - insulate that too! The key thing is you don't want any of the sacrificial part of the circuit to touch the tank and create a short circuit.
• Apply the POSITIVE lead to the sacrificial piece of iron or copper wire lead.
• Apply the NEGATIVE lead to the steel gas tank.
• Turn on the charger and it will start the process.
Almost immediately expect to see a small stream of bubbles coming up out of the water where the rust is. Let it run overnight.
Turn off everything remove the anode, and pour out the solution into a bucket. You'll have to rinse it all very well as you may have loose rust/sludge in the bottom of the tank.
If it's really rusty, repeat the process again - you can reuse the solution just filter out the crud. Solution should be able to poured down the drain as it's like laundry soap. If the anode is dirty after the first round, take a wire brush or a scotch-brite pad to it.
The rust removal is a "line-of-sight" process so you may need to move the anode around from time to time to be sure the whole tank is affectively covered. 2-amp charger is slow but will get you there, 10-amp is faster. It does not harm the tank if left running longer than necessary. It seems to leave a black residue which wipes off and doesn't seem to harm anything.
To be sure all water is out of the tank after rinsing use some high 90%+ rubbing alcohol, or acetone to remove traces of water. If the tank is going to be stored, slosh some 2-stroke oil around in it, or some folks treat it with an epoxy motorcycle tank sealer if it had been previously very rusty and the seams might be thin.
I've also used this on tools and car parts with great success. Get a plastic storage bin or a 5-gallon bucket to act as a tank. Just remember the NEGATIVE lead goes on the part you want to clean.
Small caution: The bubbles released include hydrogen which is flammable.  Keep away from flames or allow ventilation - I've never had a problem in a 2-car garage - opening the window seemed to do just fine, as it's only a small amount of gas released.
« Last Edit: January 17, 2008, 11:30:51 PM by dkruitz »



Offline MoTo-BunnY

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Re: whats the best chemical to clean rust out of a gas tank
« Reply #2 on: January 18, 2008, 12:15:45 AM »
Not to be a poOpie butt here, but dood. . . did you even TRY the search function??  this topic has been covered many, many, MANY times. .  . .using a 10 second search of "clean gas tank" I pulled up 18 FRIGGIN' PAGES!!!    LOL   ;D

In a nutshell, I used "Metal Prep" (phosporic acid) but there are lots of other ways people also swear by. .  . .

S E E:

http://forums.sohc4.net/index.php?topic=2893.0  (FAQ section - Fuel Tank & Pet cock)

http://forums.sohc4.net/index.php?topic=21623.0

http://forums.sohc4.net/index.php?topic=12288.0

http://forums.sohc4.net/index.php?topic=11215.0

http://forums.sohc4.net/index.php?topic=16740.0

http://forums.sohc4.net/index.php?topic=4840.0
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Bob550four

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Re: whats the best chemical to clean rust out of a gas tank
« Reply #3 on: January 18, 2008, 05:31:41 AM »
the electrolysis method sounds really good. Ive got a light surface rust, so I"m going to try it and see how it works out.    how long should one let the solution sit in the tank though? or does it make a difference?



Offline Jay B

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Re: whats the best chemical to clean rust out of a gas tank
« Reply #4 on: January 18, 2008, 07:10:02 AM »
Try "The Works" toilet bowl cleaner, available anywhere for 2 bucks. Dump a bottle in, slosh the tank around every 5 minutes or so to keep everything coated. In a half hour it will be clean. Rinse well, make sure it's dry, etc. I've done 4 or 5 tanks with this stuff, works like a charm on the cheap.
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Offline lrutt

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Re: whats the best chemical to clean rust out of a gas tank
« Reply #5 on: January 18, 2008, 07:51:49 AM »
The folks at the antique outboard club have mentioned using muriatic acid for steel tanks too.
Be sure to rinse well and neutralize it with baking soda, use alcohol to remove the last of the water, then coat with a light oil such as 2-stroke oil to keep it from rusting.

Also, if you like less caustic solutions, try the arm and hammer washing soda electrolysis setup to remove the rust - widely documented on the web, but here are my notes:

Rust Removal via Electrolysis
Ingredients:
• Rusty steel gas tank
• Arm and Hammer WASHING SODA (from the laundry aisle at the grocery store)
• Water
• Sacrificial iron anode (large nail or piece of re bar, etc) - NOT stainless steel
• Automotive type battery charger (2 - 10 amp works well)
Steps:
• Dissolve 1 tablespoon (more or less) of washing soda per gallon of warm water required to fill the tank.
• Fill the tank with the solution.
• Affix the anode inside the tank so that it doesn't touch metal to metal anywhere. You can use scraps of wood and/or electrical tape on the ends, built up to insulate it so it won't touch the tank. You may extend it with a piece of copper wire outside the tank if needed - insulate that too! The key thing is you don't want any of the sacrificial part of the circuit to touch the tank and create a short circuit.
• Apply the POSITIVE lead to the sacrificial piece of iron or copper wire lead.
• Apply the NEGATIVE lead to the steel gas tank.
• Turn on the charger and it will start the process.
Almost immediately expect to see a small stream of bubbles coming up out of the water where the rust is. Let it run overnight.
Turn off everything remove the anode, and pour out the solution into a bucket. You'll have to rinse it all very well as you may have loose rust/sludge in the bottom of the tank.
If it's really rusty, repeat the process again - you can reuse the solution just filter out the crud. Solution should be able to poured down the drain as it's like laundry soap. If the anode is dirty after the first round, take a wire brush or a scotch-brite pad to it.
The rust removal is a "line-of-sight" process so you may need to move the anode around from time to time to be sure the whole tank is affectively covered. 2-amp charger is slow but will get you there, 10-amp is faster. It does not harm the tank if left running longer than necessary. It seems to leave a black residue which wipes off and doesn't seem to harm anything.
To be sure all water is out of the tank after rinsing use some high 90%+ rubbing alcohol, or acetone to remove traces of water. If the tank is going to be stored, slosh some 2-stroke oil around in it, or some folks treat it with an epoxy motorcycle tank sealer if it had been previously very rusty and the seams might be thin.
I've also used this on tools and car parts with great success. Get a plastic storage bin or a 5-gallon bucket to act as a tank. Just remember the NEGATIVE lead goes on the part you want to clean.
Small caution: The bubbles released include hydrogen which is flammable.  Keep away from flames or allow ventilation - I've never had a problem in a 2-car garage - opening the window seemed to do just fine, as it's only a small amount of gas released.


You could quite literally do this with the tank on the bike yet. Interesting. I will be restoring an MG TD this summer and will no doubt need to clean the tank. May have to try this.
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Offline KB02

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Offline mustangcar

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Re: whats the best chemical to clean rust out of a gas tank
« Reply #7 on: January 18, 2008, 09:42:07 AM »
the electrolysis method sounds really good. Ive got a light surface rust, so I"m going to try it and see how it works out.    how long should one let the solution sit in the tank though? or does it make a difference?
  i did a tank for about a day, some take three days,you will have to clean the iron rod out often,as it will turn green crusty rusty very quickly.i cleaned it every 4 hours or so, don't let the tank sit with the solution with the charger on off,always running,only shut off when checking the rod and connections,,,the main hard part is putting the rod inside the tank as deep as you can while not touching the inside walls of the tank,i wrapped some visegrips with tape and cloth,which held the wire rod in place over the opening of the tank,you have to bend the wire quite a bit till you get it right,,remember not baking soda,it has to say washing soda(armnhammer brand),i had a hard time finding it,,found it at jewels food store,you can also do some chrome pieces,i did some rusty painted items and it lifted the paint(alternative bucket method setup),it will not damage the paint outside the  fuel tank as the solution is inside,,remember the tank gets the negative while the rod gets the positive charge,after the water rinse,dry quickly,some use acetone/alcohol,i just put it over a heater/blowdryer,and splashed tranny fluid in there,it will flash rust quickly if you don't oil it ,,this is the way museums clean rusty items
« Last Edit: January 18, 2008, 09:49:39 AM by mustangcar »



Offline tjjkc

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Re: whats the best chemical to clean rust out of a gas tank
« Reply #8 on: January 18, 2008, 10:18:43 AM »
eletrolysis setup-----good pictures and explanation

http://www.altelco.net/~jacil/clay/motorcycle/KElecSetup.html
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Offline dkruitz

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Re: whats the best chemical to clean rust out of a gas tank
« Reply #9 on: January 18, 2008, 10:20:20 AM »
re: Electrolysis
I've done tools, and other assorted bits. Generally anywhere from a few hours to overnight.  The biggest thing I did was a flywheel from a little Crosley engine  http://downloads.kruitzkraft.com/crosley/images/hpim2576.jpg it had to sit in the solution about a whole day.  On that same engine, I'm going to try to de-rust the whole block eventually too.

Yes clean the sacrificial iron piece as it can junk up and inhibit the electrical process.  It's line of site, so doing some gas tanks may be a real PIA owing to the hump for the frame.  Leaving it overlong doesn't hurt the metal on the the rust. 

WASHING SODA can be bought online from various sources too.  I've heard you can use salt as an alternate, but me personally, I don't want to introduce salt to steel - I've lived up north and seen the results.


If in doubt, try it in a plastic bin on something old and rusty - works great and is safe.
« Last Edit: January 18, 2008, 10:26:10 AM by dkruitz »



Offline JAG

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Re: whats the best chemical to clean rust out of a gas tank
« Reply #10 on: June 19, 2008, 12:57:01 AM »
I know I'm starting back up and old thread, and this stuff has been beat to death, but this question, no matter how many pages I go through still hasn't been answered.

I just had my tank painted.. I mean it was literally finished today. And I, in no way shape or form, want to damage the paint job. Will any of these methods of de-rusting destroy the paint job?

I know Acetone can and will, and I would believe the muriatic acid and phosporic acid could too.

I don't have a horribly rusted tank. I however do have flakes of rust shaking around inside of it.

Is it possible to just get away with throwing some nuts and bolts/bicycle chain inside of it and shaking the **it out of it, and not worrying about the de-rusting, and coating methods?

And maybe after that installing an inline fuel filter for good measure.

Sorry to be that GUY, but I'm really worried about screwing up my paint job, as I'm not the most graceful person in the world. ::)
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Offline KB02

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Offline Wayne Meuir

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Re: whats the best chemical to clean rust out of a gas tank
« Reply #12 on: June 19, 2008, 07:42:54 AM »
I have done a bunch of tanks using electrolysis and although I have never had it damage good paint, it can because others have had it happen.  One of my friends had a fresh paint job and what he did was cut a hole in a plastic trash bag and tape it around the tanks filler with the blue painters tape and then drape the bag over the tank so all the spillage runs off. Be sure to wash the inside of the tank at a car wash or with a pressure washer before you start to get all the old gas residue out.

Another note:  A good way to set up the anode is to use 3/16" all thread from Home Depot and a plastic cap from a paint rattle can. Cut whatever slots are necessary in the cap so that it will sit right down on top of the tank over the filler neck. Drill a 3/16" hole in the middle of the plastic cap. Bend the all thread into an L.  Thread a nut onto the short end of the L, then a flat washer. Slide that through the hole in the cap, add another flat washer and nut on top.  Now fill the tank with the solution.  Stick the long end of the all thread down into the tank with the long end pointing toward the rear of the tank and not touching metal ANYWHERE. Set the cap down over the filler opening.  Hook the + Battery charger lead onto the all thread.  Hook the - battery charger lead to any bare metal on the tank(bracket where it mounts underneath works well) Then turn on the charger.  I have had it take a week running 24 hours a day to clean a really bad tank, BUT, you aren't doing anything most of that time.

The solution can be made from a lot of different stuff.  I use TSP Substitite from Lowes.  For $10 you get a lifetime supply.  Arm and Hammer Washing Soda is good but hard to find. I used Baking Soda on one tank and it worked fine as well.  Basically all this stuff is a form of Sodium Carbonate(Soda Ash, sodium Bicarbonate, etc) and all work equally well.
You can also get it a pool supply places.

The good thing about this process is, when you are done there is ABSOLUTELY NO RUST anywhere in the tank, all that is left is bare, clean metal and it WILL NOT harm good metal. You can tell when it is clean because the stuff sticking to the rod will become a whitish crystalline looking product.

I always coat the tanks after I am done with POR15 but I know others who simply put a little oil inside and slosh it around until they are ready to use it.  I figure if it si sealed I completely eliminate any future problems.
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