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Author Topic: How to remove rust from the inside of tank?  (Read 4765 times)

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Offline BrandonB13

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How to remove rust from the inside of tank?
« on: January 28, 2011, 05:24:18 PM »
I need to clean the inside of an old tank. It has plenty of surface rust. Can it be done chemically?
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Offline fmctm1sw

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Re: How to remove rust from the inside of tank?
« Reply #1 on: January 28, 2011, 05:30:40 PM »
Not trying to be a wise guy but lots of threads here on that.  Just search for "tank cleaning" or the like....
re: burnouts thread 
Quote from: 754
Dude is that a tire ? or an O-ring..??

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Offline Retro Rocket

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Re: How to remove rust from the inside of tank?
« Reply #2 on: January 28, 2011, 05:46:13 PM »
Not trying to be a wise guy but lots of threads here on that.  Just search for "tank cleaning" or the like....

Yep, tons of info on that subject.... ;)

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Offline Magpie

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Re: How to remove rust from the inside of tank?
« Reply #3 on: January 28, 2011, 05:53:35 PM »
If you're a patient person, I mixed a litre of molasses and the rest water to fill the tank, after I plugged the holes for the fuel tap, and let it sit for a week or two. It works. Stinks though. Cliff.

Offline TwoTired

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Re: How to remove rust from the inside of tank?
« Reply #4 on: January 28, 2011, 05:58:46 PM »
I need to clean the inside of an old tank. It has plenty of surface rust. Can it be done chemically?
It CAN be done chemically but acids dissolve both rust AND metal, which can leave you with holes.

On the other hand, Electrolysis and some patience will dissolve the rust and leave the base metal alone (with correct polarity).

I favor the electrolysis method for rust removal, then a quick Phosphoric acid treatment to convert the remaining surface and leave a phosphate coating.  The acid does convert a thin layer of metal, but it also is self limiting as to how deep it converts.  A phosphate coating is no longer susceptible to phosphoric acid.  And, it doesn't flash rust nearly as bad as other acids which just leave bare steel exposed.

This should give you some keywords for searching.

Cheers,
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Offline fire113

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Re: How to remove rust from the inside of tank?
« Reply #5 on: January 28, 2011, 06:16:13 PM »
I need to clean the inside of an old tank. It has plenty of surface rust. Can it be done chemically?
It CAN be done chemically but acids dissolve both rust AND metal, which can leave you with holes.

On the other hand, Electrolysis and some patience will dissolve the rust and leave the base metal alone (with correct polarity).

...found a special company that can do it chemically in the ph neutral range without removing metal! and the result is real good.
http://www.abbeiz.de/html/entrosten.html

good luck...Georg
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Offline Popwood

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Re: How to remove rust from the inside of tank?
« Reply #6 on: January 28, 2011, 08:08:29 PM »
+1 on TT's advice. I've had good success with electrolysis several times. Non invasive and inexpensive. Gets the job done. Just be patient.
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Offline octagon

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Re: How to remove rust from the inside of tank?
« Reply #7 on: January 28, 2011, 09:33:39 PM »
before you go to too much trouble, you might take a sharp ice pick or something similar, turn the tank over, and press the point all over the bottom surface - kind of like looking for rotten wood. if you find you can poke holes or if the metal gives because it's so thin then you're looking at some welding or junking the tank. there are coatings and jbweld fixes and stuff like that out there, but a lot of those solutions fail. 

Online ekpent

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Re: How to remove rust from the inside of tank?
« Reply #8 on: January 29, 2011, 06:57:08 AM »
One word of warning would be if you use any type of acid like the Works toilet bowl cleaner etc make SURE the petcock and anything else in aluminum has been removed and does not come in contact-----


Offline Leanier

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Re: How to remove rust from the inside of tank?
« Reply #10 on: January 29, 2011, 11:00:59 AM »
I'm going to second the electrolysis.  used it on one of my tanks I got.  rustiest thing id ever seen.  got it sparkling clean, however, also caused alot of pinholes.  But that was just because the tank was far to rusty.  no metal left.
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Offline PHeller

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Re: How to remove rust from the inside of tank?
« Reply #11 on: February 07, 2011, 06:26:15 AM »
quick question since this is the most recent thread:

can you sacrificial anode touch the inside of the tank?

I've heard that the rust like a direct route to the anode, and that sometime electrolysis doesn't get into the nooks and crannies of the tank because the rust cant get pulled to the directly to the anode.

So, would a coat hanger that reaches to the depth of the tank, even if its touching the tank, be ok?

Offline GammaFlat

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Re: How to remove rust from the inside of tank?
« Reply #12 on: February 07, 2011, 06:45:11 AM »
I've done the electrolysis method and built something small enough I could drop in a tank through the filler opening.  It had two flat ends made of wood (to avoid having the wrong parts touch the outside of the tank) with nails connecting the ends.  I had a wire leading to the nails.  I think it took a couple days.  The biggest pain was having to check on it and cleaning the gunk off of the nails.  I was also switching sides of the tank that I left it in. 
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Offline cobrajunkie

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Re: How to remove rust from the inside of tank?
« Reply #13 on: February 07, 2011, 08:35:28 AM »
quick question since this is the most recent thread:

can you sacrificial anode touch the inside of the tank?

I've heard that the rust like a direct route to the anode, and that sometime electrolysis doesn't get into the nooks and crannies of the tank because the rust cant get pulled to the directly to the anode.

So, would a coat hanger that reaches to the depth of the tank, even if its touching the tank, be ok?

From my above link...

 "The idea with the sacrificial anode is to insure that it does not touch the tank anywhere, you must insure it only come in contact with the washing soda solution or you will have a direct short."

Offline Popwood

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Re: How to remove rust from the inside of tank?
« Reply #14 on: February 07, 2011, 09:15:32 AM »
And the anode is "line of site directional" to a large degree. You'll need to move it from one side of the interior tank hump to the other. I just moved it once a day, something like that. Or, when the anode is so cruddy with junk and you need to remove for cleaning.
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Offline lrutt

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Offline Scott S

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Re: How to remove rust from the inside of tank?
« Reply #16 on: February 08, 2011, 07:00:25 AM »
 I tried the electrolysis method on a pretty rough XS650 tank. I didn't think it was working too well; it took quite a while and left a rough, scaly looking finish. That said, it stayed rust free for more than a year with no fuel in it.

 My latest favorite method is "The Works" toilet bowl cleaner and a length of heavy chain. Swish it around to knock out loose rust and then drain the cleaner out. Rinse, then rinse again with a liberal amount of baking soda mixed in the water to neutralize the acid. Air dry ( I also like to swish around some denatured alcohol to help dry out any moisture) and then coat with some Marvel Mystery Oil until you're ready to put gas in it.
 This method works VERY well with tanks that have minor or surface rust. Heavier rust may dictate lining with Redkote, POR15,etc. after doing this.
 Admittedly, the XS tank was in much worse shape than the last few that have gotten the "Works" method.
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Offline fmctm1sw

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Re: How to remove rust from the inside of tank?
« Reply #17 on: February 08, 2011, 07:32:59 AM »
I'm a toilet bowl cleaner guy myself.  I haven't used the baking soda follow up you mention though.  I did my 350F tank coming up on two years ago now with The Works and a POR-15 liner.  I have two 550K tanks with light rust.  I may see if I can neutralize the acid and NOT line it and see what happens.
re: burnouts thread 
Quote from: 754
Dude is that a tire ? or an O-ring..??

2008 XR100
1973 CB350F (Road legal)
1975 CB550K (Road legal)
1983 GL650I http://forums.sohc4.net/index.php?topic=132802.msg1486130#msg1486130
1973 CB750K3 (http://forums.sohc4.net/index.php?topic=92888.0)
1984 Kawasaki KLT-250 (AKA 3 wheeler of death)

Offline Scott S

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Re: How to remove rust from the inside of tank?
« Reply #18 on: February 08, 2011, 08:35:50 AM »
 I did another XS650 tank and it took it down to bare metal....like new inside. I coated it with Marvel Mystery Oil and gave it to the body shop. They held the tank captive for almost a YEAR. When I got it back, it still had a light film of oil and NO rust. I just added gas and away I went!
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Offline TwoTired

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Re: How to remove rust from the inside of tank?
« Reply #19 on: February 08, 2011, 10:21:01 AM »
I tried the electrolysis method on a pretty rough XS650 tank. I didn't think it was working too well; it took quite a while and left a rough, scaly looking finish. That said, it stayed rust free for more than a year with no fuel in it.

Elecrolysis didn't leave a rough scaly looking finish, the rust did!

Besides, no one said it was impossible to screw up the "electrolysis method" by using the wrong polarity, wrong type of soda, the wrong solution strength, or the wrong current levels.  Properly done, it works as described.

But, that's no reason to damn a method.  It IS clear that acids will attack the base metal.  If you have some base metal to spare, then fine.  But, if the metal is thin, you'll have to patch pin holes where the acid ate through.

If rust is the only remaining barrier to keeping gas inside, then you will get pin holes with the proper electrolysis method, too. BTDT

Cheers,
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72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC

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Offline Ernest T

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Re: How to remove rust from the inside of tank?
« Reply #20 on: February 08, 2011, 04:39:19 PM »
I like POR 15.


everything you need comes in the kit, you use an acid cleaner called marine clean, then something called metal ready to remove the marine clean residue.



Makin sure it gets all over the tank


Drying it in the oven before sealing.  I did two hours at 200 degrees.  Don't do this with the wife at home :D


Dump the sealer in the tank to cover the bare metal



Itl leaves a silver colored finish and will seal pinholes.

Offline Scott S

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Re: How to remove rust from the inside of tank?
« Reply #21 on: February 08, 2011, 05:04:53 PM »

Besides, no one said it was impossible to screw up the "electrolysis method" by using the wrong polarity, wrong type of soda, the wrong solution strength, or the wrong current levels.  Properly done, it works as described.

But, that's no reason to damn a method.  It IS clear that acids will attack the base metal.  If you have some base metal to spare, then fine.  But, if the metal is thin, you'll have to patch pin holes where the acid ate through.


Cheers,

 I wasn't damning the method. Just relating my experience. If anything, what I said is proof that it DOES work and I must have done it correctly. The resulting finish stayed rust free for more than a year with no other treatment.
 I prefer to start with a better tank when possible and use The Works method. I've had great luck with that.
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Offline Dyrden

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Re: How to remove rust from the inside of tank?
« Reply #22 on: February 08, 2011, 05:11:45 PM »
Electrolysis is like magic for lazy people.  Works like a charm and you can sit inside watching tv and drinking a beer while the electricity does the work.  Like stated above, its self limiting, cheap and thorough.  Ive done it and spent less than 40 bucks on the gear(already had a 12v battery charger).

Good luck. 

Offline brooze72

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Re: How to remove rust from the inside of tank?
« Reply #23 on: February 08, 2011, 06:00:02 PM »
I used the tumble method, slow but effective, 6 to 8 hours with some small abrasives in the tank & a little solvent.  Welded a couple of ears on a pipe to pick up the front tank mounts, a little tape & voila! came out very nice.  A few buddies suggested padding the outside of the tank & putting it in the dryer.  I didn't have the nerve to try & slip that by SWMBO
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Offline pearsonm

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Re: How to remove rust from the inside of tank?
« Reply #24 on: February 08, 2011, 07:31:12 PM »
I wanted to go the least-caustic route so I started off with two rounds of vinegar. It got a majority of the crap out but there were still some stubborn spots I had to get with The Works. I followed up with baking soda to neutralize the acid, Heet and compressed air to evaporate the water and Marvel Mystery Oil to coat.

As has been said, pull the fuel tap and the filter if your tank has one of those stupid tampon-type units.
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