Using muriatic acid to remove rust from a gas tank

[Dammit!]

Did a search but still have a bunch of Q's. Lets get the bases covered for anyone doing a search in the future.

My 200x tank has a terrible, half-assed kreem job done to it. The idiot didn't remove the rust first so it's a real mess in there. Just nasty. I was planning to use muriatic acid to remove the rust.

Will it remove the kreem as well?

Should I dillute the acid? By how much?

How long should I leave it in there?

I assume it will ruin the petcock?

Cap on or off?

Will it instantly ruin the paint?

When it's done soaking, then what? Poor it out? What neutralizes this stuff?

Also, did these tanks have any kind of lining when they were new? I'd rather not use more kreem in it. I would just keep the tank full. Condensation isn't a real concern out here in the desert. ;)

[Huffa]

Will it (muratic acid) remove the kreem as well?

NO. Must use acetone 1st.

Should I dillute the acid? By how much?

Depends how badly rusted it is. 50/50 would be a good ratio.

How long should I leave it in there?

As long as it takes to netralize it. Real bad ones at least 12 hours. Shine a flashlight in to inspect every few hours or so. Won't hurt if you leave it in for even longer.

I assume it will ruin the petcock?

You don't use the petcock. Well if it is thew screw on type then you do use it but with plastic filter tube off and put a rubber plug up hole first. If the petcock bolts in then you take it off and make a plate with a inner tube piece sandwiched between.

Cap on or off?

Cap off.

Will it instantly ruin the paint?

NO!

When it's done soaking, then what? Poor it out? What neutralizes this stuff?

Yep, pour it all out and flush with water to neutralize. Then rinse with acetone. You will get flash rust almost immeadiatly though so pour gas right back in once petcock is back on.

Also, did these tanks have any kind of lining when they were new? I'd rather not use more kreem in it. I would just keep the tank full. Condensation isn't a real concern out here in the desert.

NO, Harleys & BMW's I think come with a lining in them though.

Hope I helped .

[Dammit!]

I thought acetone was just a neutralizing agent? That stuff will remove the kreem?

[83185s]

yes definetly make sure * use the acetone...i didnt and my tank is already almost as bad as it was before..reason i didnt use it is because 1. i ditn have any.. 2 i didnt have money to get any..3..im stupid and thought swishing around some 2 stroke oil would coat it and then flush it out with gas and it would be fine..well guess what..didnt work..its bad and i hate myself for it..but..it doesnt put any rust in the carb now that i ran most of it out of the tank..and yes it will ruin your petcock if you dont take it out like i did...mine is gone..all i have left is a peice of plastic and a couple o ring gaskets..lol..nothing else..its desintgrated in the acid/water...also..i used 1 gallon of the acid and 4 gallons of water..this stuff will ruin your tank if you dont be carefull about it..and ive had to jb 2 holes in the tank already...on the bottom by the petcock..they were pinholes but thats not good when * fill ** tank with 93...just take my advise...do what huffa told you..lol

[Huffa]

I thought acetone was just a neutralizing agent? That stuff will remove the kreem?

Yea but it is no simple task! I know because I had a bad batch of kreem once (too thick) and had to take it all out! WHAT A JOB! I used gallons of it (acetone) to get it out.

It says so right in the kreem directions to use it for removal.

Took days of swishing and sloshing the tank around to remove it but that was the only way, I had no choice.

My fault though as I thought it was coming out too slow but it's been years since I did one so just assumed it was that way. If it flows too slow it's a real pain to get inside tank cocverage. It will NEVER happen again to me though, thats for sure!

[Huffa]

yes definetly make sure * use the acetone...i didnt and my tank is already almost as bad as it was before..reason i didnt use it is because 1. i ditn have any.. 2 i didnt have money to get any..3..im stupid and thought swishing around some 2 stroke oil would coat it and then flush it out with gas and it would be fine. .well guess what..didnt work..its bad and i hate myself for it..but..it doesnt put any rust in the carb now that i ran most of it out of the tank..and yes it will ruin your petcock if you dont take it out like i did...mine is gone..all i have left is a peice of plastic and a couple o ring gaskets..lol..nothing else..its desintgrated in the acid/water...also..i used 1 gallon of the acid and 4 gallons of water..this stuff will ruin your tank if you dont be carefull about it..and ive had to jb 2 holes in the tank already...on the bottom by the petcock..they were pinholes but thats not good when * fill ** tank with 93...just take my advise...do what huffa told you..lol

Yes, you were stupid but I respect you for being honest and sharing a laugh with us! :beer

[70binder]

keep baking soda on hand so you dont wonder why the acid ate your skin. regardless of acidity, it still takes the same amount of baking soda to neutralize :w00t: so dont think you have to buy pounds upon pounds to keep it in check

[Oldshell4481]

keep baking soda on hand so you dont wonder why the acid ate your skin. regardless of acidity, it still takes the same amount of baking soda to neutralize :w00t: so dont think you have to buy pounds upon pounds to keep it in check


been watching fight club, huh? lol.. ive heard alot of bad about kreem, if done correctly how long will it last??

[Huffa]

been watching fight club, huh? lol.. ive heard alot of bad about kreem, if done correctly how long will it last??

Forever!

You want a nice thin coat. Usually 1/2 the bottle of kreem drains back out and you can recoat again if you feel the need too.

Puddeling is a big no-no too. You leave set on one side 8-10 minutes then rotate tank slowly all ways (with cap back on) then set on another side & take cap off. Do all sides till satisfied it's got full coverage and drain the remainder of kreem out.

[jenndnn3]

Dammit, You will have to retreat it. I dont know if this was mentioned before. But whomever took these steps previously has "etched" your tank. It will rust unless retreated.

Kreeme works extremely well, its just an extremely anal process.

[ClayW]

Well first off, muratic acid is already a very mild acid. Its mostly water to begin with. Put it in the tank straight out of the gallon jug. Fill it up and let it sit for about 20-30 min. It will eat all the junk and leave a nice dull gray finish. Just dump it out into a 5 gallon bucket. If you need to do it for a little longer you can dump it back in. When its done, dump it out and rinse it out with the hose pretty good. I personally then dump some baking soda in there to neutralize anything thats left in there. Then I rinse it out real good again. When thats done, I pour a good bit of acetone in there to get the water out. Then I use Redcoat to line the tank. Its much tougher and forgiveing than Kreeme. You may have to use acetone ( quite a bit ) to get that old kreeme out. I dont know if the acid will eat it or not. Hell you could try it. I have done many a tank that way. Cant beat it. The acid in the Kreeme kits is a even milder acid than muratic. They do this so the consumer doesnt burn themself and sue them. LOL. Muratic is cheap and fast :beer

[Dammit!]

This stuff (the acid) is stronger than I expected. I poured about two thirds of a gallon in at full strength and I could instantly see and even hear it cooking inside. Rust was coming right off. Accidently inhaled some of the fumes. Don't do that. Filled the tank the rest of the way with water and just letting it soak right now.

I got the kreem out without the acetone by the way. It was such a bad job that I managed to pull the entire thing out by hand. I can't wait to see how nasty the carb is...

[Dammit!]

You guys weren't kidding about the flash rust. Did it even out here in the dry climate.

Where do you get Redcoat at? Do you have to wait for the acetone to completely dry out before applying it?

I'm gonna need a new gas cap too. Mine is pretty much shot.

[ClayW]

I get mine from a autoparts store up in Mich. John Swinehart AKA Jeswinehart gets it for me. I paypal him the money for it and the shipping. Runs about $28 shipped for a qt. The acetone doesnt hurt it, just thins it a little. It leaves a nice thick red lining. Kinda like the stuff you dip plier handles in. A half a qt will do a tank. I did PatBlackwells tank with it. I was able to fix a hole the size of a ink pen with it. GOOD STUFF! Pats tank has about a 1/8 inch think liner in it. Kreeme is crap in my book and many other peoples. Redcoat is the bomb. :D PM John and see if he can get you some. Just send him the money. I cant find it down here in GA. Check around your area if you want. It was originally made for Aircraft tanks. Thats why its so readily available in the midwest ( Lot of aircraft type stuff goes on up there). By the way, The muratic acid is tough, but it wont hurt a thing. Just dont leave it in there for too long. Monitor it. Its good to put it in there strong because ANY potential holes will show up. THen you can fix them. Instead of messing around and a month or two and then suddenly a leak forms. Pain in the butt. Especially if you have painted the tank. PM John. Tell him Clay sent ya. :beer

[Mr. Sandman]

As Clay mentioned above, use baking soda to neutralize the acid prior to doing a final flush or the acid will continue to eat away at the welds/seams.

[Yamahauler]

this is an old thread but i was wondering if I poured some muriatic acid in full strength and got the rust out, would I have to Kreem it? Or can I just leave it bare metal like they were out of the factory?

[hondatrikesrule22]

this is an old thread but i was wondering if I poured some muriatic acid in full strength and got the rust out, would I have to Kreem it? Or can I just leave it bare metal like they were out of the factory?

Yes, you will have to coat it. As soon as you pour the acid out, pour in baking soda and water. Rinse that out and rinse it with acetone. Youi must use acetone, or you will have more rust than when you started. I tried this and it was a disater. I am just going to spend $35 bucks to have the Radiator shop do it. :D

[cool_racer]

who ever brought this back thanks. really helpful. called my dad and he had a couple of gallons at the shop. soon as i get some kreeme or red coat im doin my 70 tank :D

[kilabeez0]

just curious as to where you guys dump these chemicals when your done? bucket? barrel? sink? and how much baking soda do you mix in, a box?

[Dammit!]

who ever brought this back thanks. really helpful. called my dad and he had a couple of gallons at the shop. soon as i get some kreeme or red coat im doin my 70 tank :D

Thought I'd mention this stuff is called Red Kote. Not Red Coat. Might have an easier time finding it knowing how it's spelled. ;)

[hiltu]

I have light surface rust inside my 185s tank, if i use muriatic acid to clean it out, than baking soda to neutralize it, followed with some acetone can i just throw some gas in and go, or DO i NEED to red koat/kreem?

[Dammit!]

I have light surface rust inside my 185s tank, if i use muriatic acid to clean it out, than baking soda to neutralize it, followed with some acetone can i just throw some gas in and go, or DO i NEED to red koat/kreem?

You will need it use red kote or kreem. The acid etches the surface and it will flash rust damn near instantly.

Supposedly with red kote you don't really need to use the acid. Some surface rust won't make it not stick to the tank like kreem. I didn't want to take any chances and went the whole 9 yards though.

[Solid Snake]

Good point Dammit, you don't need to get all the rust off with Red-Kote, with Kreem you will though. The flash rust happens so fast that I'm not sure it's avoidable. I've done two tanks, one with the Kreem acid and another with muriatic acid, baking soda, and acetone, both times I got flash rust (just a little) within a minute or so. Anyway, the Red-Kote was uneffected by it and has held up excellently.

[N5HNY]

I use cheap toilet bowl cleaner in my tanks to get the rust out. It costs about $.99 and does a great job. Muratic acid is still strong and can eat a fuel tank up and leave pinholes if it is extremely rusty. You can flush it out with water and then use the acetone to prep for the Kreem.

I have tried the Kreem "kit" before but I was not too impressed with it. I am sure there are other brands out there that do a better job.

[mudbogger]

I dont know if I passed it by or not, but I have brought many of my fuel cells that were rusted to my local radiator shop guy, he boils them- pressurizes them and reboils them, they come out perfect and it was not expensive at all, I am currently still using the fuel cells and have no issues with them at all, just dont let him paint it for you, there painting processes really stink-lol

[ATC90UK]

Hi, i have always used white vinegar to derust tanks. Works a treat, is cheap and you just chuck it down the drain when you are done. You can also mix it 50 - 50 with water and it still does a good job. Cant get better for the price.

[rally4x4racer]

I have to disagree with the notion that "You must put a liner in the tank if you etch it" If it is already rusty the surface of the metal is "open" and etching it will make it no worse. You can prevent your tank from rusting any worse, or stop the flashing by oiling it. I am not sure how well this works with muretic because I use phosphoric, but I would assume the reaction is similar.

I have "etched" more than one tank and not lined it. No problems. I also "etch" almost all my smaller parts and spray them with WD or something right after rinsing and drying.

Hey dammit!. which is worse - sniffing the muretic or the MEK, or kreem? LOL!!

[Dammit!]

I didn't try sniff anything but Muriatic and it's nasty stuff. I don't recommend it. :lol:

[rally4x4racer]

I have accidentally inhaled a few compounds. phosphoric and muretic are both pretty bad when they are kicking.

[tri-Z ripper]

bump sorry guys a year old but is phosphoric acid some really potent stuff or available anywhere?

[dickieg89]

my wife is a chemical and bio grad and works with this stuff on a daily basis, if you need questions asked just pm and i'll have her give you her best answer

[Dammit!]

bump sorry guys a year old but is phosphoric acid some really potent stuff or available anywhere?

When muriatic acid is available just about anywhere, I don't know why you want to use anything else.

[TravEX]

Gonna try the Red Kote in a few days. Read all of this have a couple of questions.

Does the petcock filter tube just pull out?

When I drain the RK, do I use a wire brush/Q-tips to clear out the petcock filter hole so that the filter can be re-installed? Do I re-install the filter as soon as I leave the tank to dry?

3 steps to the prep, right? Muriatic acid, baking soda flush, and then acetone. And the flash rust will be fine when using the RK.

Thanks

[Dirtcrasher]

I pushed the filter tube into the tank with a punch and got it out the fill hole....

[TravEX]

Is it re-usable when you do that?