Author Topic: Prep and etch tank rust removal (Read 9680 times)

Leganto · « **on:** October 16, 2011, 10:25:03 AM »

Last night i had a couple hours with no kids or wife. So i thought i would work on my 550. I have read up on the phosphoric prep and etch method here on the forum and decided to try it.

I threw some nuts and bolts in there and shook for a while. Got em out with magnet. Then rinsed with water to get as much rust out as I could. Then I plugged the tank up and put all of the prep and etch in there.

After moving it around every once in a while to let it work on all sides I took a look inside and saw that slot of the rust was gone, and the grayish film left behind. So far so good.

I was running out of time though...and there was still rust in there. I filled the tank the rest of the way with water and left it over night.

Overnight some of the stuff leaked out....and flash rust developed in the upper areas. But it seemed to get rid of most of the bottom rust.

I just dumped it and rinsed with water. Then I rinsed with acetone. I am leaving out some of the trouble I had and steps....but I ran out of baking soda last night...so I hope the water rinse was enough to take care of it.

I still have rust.....but just flash. I am sure I made too many mistakes....and I just didn't have enough time to redo things. I basically feel like I wasted that time and supplies.

Hopefully it will be a little faster and easier next go around.

Any hints or suggestions?

Once I get this handled I plan to post a very detailed explanation of this. I know there has to be others with small children and little time to waste on mistakes.

Tews19 · « **Reply #1 on:** October 16, 2011, 10:34:23 AM »

Evaporust works great and is not bio hazard..... Cleans up real nice. I made a post of the pics when I used it on both my tanks

Leganto · « **Reply #2 on:** October 16, 2011, 10:52:22 AM »

If I abandon my current method.....I have to find really good instructions. I really can't afford to waste much more time screwing up. At least I am learning alot.

Tews19 · « **Reply #3 on:** October 16, 2011, 10:59:57 AM »

Best and easiest intrsuctions----

Autozone, buy Evaporust for 20 a gallon, have tank empty..
Go to a hardware store, purchase a plastic cork to put in where petcock goes.
Pour in and let sit.

Rigid · « **Reply #4 on:** October 16, 2011, 11:42:45 AM »

By phosphoric I take it to mean toilet bowl cleaner? I have had good luck with that in diluted form with water. Once the rust is gone, it must be rinsed with plain water, lacquer thinner, compressed air dried, and then coated within a few minutes. That will eliminate the flash rust. I haven't tried evaporust because it cost 20x what I use. Just can't justify it. The toilet bowl cleaner can be reused over and over thereby never introducing it into the environment. Kinda like smoking cigarettes without exhaling.

Leganto · « **Reply #5 on:** October 16, 2011, 06:55:22 PM »

Phosphoric Prep and Etch is a product made by Kleen-strip. It's phosphoric acid as far as I know.

Since my first attempt converted the biggest part of the rust, I think I will try it again. It should take less time to just clear the surface rust. Also, I will try getting something better to stop up petcock hole(I cut the finger off of a nitrile glove and used rubber bands to hold it on the first time).

I used up all of my baking soda and water removal supplies...so I have to restock anyway.

New plan:
1 stopper the petcock hole.
2. Pour in the phosphoric prep and etch(use what is left of my diluted mixture or get another bottle?)
3. Wait about 30 minutes....shaking it every once in a while.
4. Pour it all out and inspect...go back to step 2 if there is still rust.
5. Neutralize with baking soda water
6. Rinse until clear.
7. Get water out with heet or alcohol or acetone.
8. Dump some marvel mystery oil in there.

I just hope I didn't damage the tank by leaving the stuff in overnight, and then only rinsing with water.

Rigid · « **Reply #6 on:** October 17, 2011, 04:07:06 AM »

No damage done with that process. If it leaks, it was rust in tiny pits that had gone all the way through in the first place. Now, about that MMO........that will work to keep rust off until you add gasoline the first time. That will remove the MMO and expose the bare metal again. You can keep the tank full, always, and that will really help keep it from rusting again. I have used Kreem plastic type sealer, as well as the same basic product from NAPA because it is cheaper. The liner/sealer has to be applied to clean metal, no MMO, allowed. There are many old threads on this if you have time for some casual reading. :-)

boticki · « **Reply #7 on:** October 18, 2011, 05:57:02 AM »

Another good tank sealant is Red Kote. Two rounds of some CLR diluted 50% with water. Flush with Alcohol. Blew dry, compressed air thru it and then put the sealant in. Swished it around for a while and then drained out the excess. I did a fair amount of research before using it. You can buy it on ebay for ~$30.

Rigid · « **Reply #8 on:** October 18, 2011, 06:01:20 AM »

As with all the sealers, Red Kote is sensitive to poorly prepared metal. The tank has to be clean, rust free, and have no oil, water, or solvent, residue immediately prior to coating.

Duanob · « **Reply #9 on:** October 18, 2011, 09:36:01 PM »

Leganto, next time you derust the tank, make sure you fill it all th way. Then when you rinse it out use the acetone. Then when you drain everything out of the tank, get some fogging oil for boat motors and spray the the inside of the tank real good. The you can store it as long as you need. Flash rust happens pretty quick so rinsing with water makes it rust even faster.

I used the Prep and Etch it worked great for derusting.

Danno · « **Reply #10 on:** October 18, 2011, 09:51:27 PM »

use the evapo rust get 2 gallons let it sit over night plug your vent and turn the tank over and let it sit over night again it took three days but the tank looks like new

fmctm1sw · « **Reply #11 on:** October 19, 2011, 10:30:18 AM »

A freeze plug works well as a cork for the tank cap...

Cevan · « **Reply #12 on:** October 19, 2011, 12:19:03 PM »

I find that drying it with a heat gun until the tank is hot is essential. Not having the tank completely dry is one reason the tank coatings fail.

Smoke Detector · « **Reply #13 on:** October 19, 2011, 12:30:55 PM »

I just used vinegar to clean a tank. Worked well but took about 5 days total, partly due to me not being familiar with the process. I started with a nitrile glove finger to block petcock hole but then it leaked, so I used the two petcock screws with gaskets to plug those holes, and then I found one of those plastic drywall/concrete expanding plugs that hold screws was a perfect fit for the centre hole. I put a screw in and gently tightened to make a seal - held without losing a drop for about 4 days.

Leganto · « **Reply #14 on:** October 21, 2011, 07:11:13 AM »

It continues.

I just plugged and applied the prep and etch again. It cleared up the flash rUst from what I can tell. But now there are a bunch of pinholes leaking in the bottom of the tanks backend.

It is leaking like crazy.

So....I need to either get a new tank or use a coating. If I stop where I am now....it will just flash rust again....but....if I put oil in there to stop the flash rust....the coating will not stick properly.

Not sure what I should do next.

lucky · « **Reply #15 on:** October 21, 2011, 07:32:28 AM »

Quote from: Rigid on October 16, 2011, 11:42:45 AM

By phosphoric I take it to mean toilet bowl cleaner? I have had good luck with that in diluted form with water. Once the rust is gone, it must be rinsed with plain water, lacquer thinner, compressed air dried, and then coated within a few minutes. That will eliminate the flash rust. I haven't tried evaporust because it cost 20x what I use. Just can't justify it. The toilet bowl cleaner can be reused over and over thereby never introducing it into the environment. Kinda like smoking cigarettes without exhaling.

"toilet bowl" acid is muriatic acid and is much ,much stronger than phosphoric acid.

Phosphoric acid is in every living thing. Just not in high concentrations.
Phosphoric acid mixed with water turns iron oxide(rust) into iron phosphate which stops the corrosion. But the metal must be coated within 4 hours or the corrosion process will start all over.

BTW... do NOT use muriatic acid to regularly clean your toilet!!! When you flush it ultimately goes to the ocean and kills. That is why you do not see it in grocery stores in the cleaning section anymore. Use other less lethal cleaners to clean your toilet.

lucky · « **Reply #16 on:** October 21, 2011, 07:34:39 AM »

Use very warm or hot water with the phosphoric acid and it works much faster than with cold water.

When you use the KREEM brand tank sealer it even tells you to use warm or hot water with the phosphoric acid, (metal etch).

lucky · « **Reply #17 on:** October 21, 2011, 07:37:33 AM »

Quote from: Leganto on October 21, 2011, 07:11:13 AM

It continues.

I just plugged and applied the prep and etch again. It cleared up the flash rUst from what I can tell. But now there are a bunch of pinholes leaking in the bottom of the tanks backend.

It is leaking like crazy.

So....I need to either get a new tank or use a coating. If I stop where I am now....it will just flash rust again....but....if I put oil in there to stop the flash rust....the coating will not stick properly.

Not sure what I should do next.

The rust and scale were keeping it from leaking.
It sounds like you need a new tank. Save the sealer for another job.

You would not just want to depend on the sealer to keep the tank from leaking. It would be a fire hazard if the coating leaked.

Rigid · « **Reply #18 on:** October 21, 2011, 07:42:03 AM »

Kreem is designed to seal pinholes, I think it even states that in the instructions. Two or three applications with drying time between may be necessary to build a suitable coating thickness. A new tank certainly is an option and is about the same money as a can of Kreem or another coating process.

Duanob · « **Reply #19 on:** October 21, 2011, 08:39:18 AM »

Quote from: Leganto on October 21, 2011, 07:11:13 AM

It continues.

I just plugged and applied the prep and etch again. It cleared up the flash rUst from what I can tell. But now there are a bunch of pinholes leaking in the bottom of the tanks backend.

It is leaking like crazy.

So....I need to either get a new tank or use a coating. If I stop where I am now....it will just flash rust again....but....if I put oil in there to stop the flash rust....the coating will not stick properly.

Not sure what I should do next.

If you have the time and tenacity I would try the heat gun method. But don't waste a minute after rinsing, start drying as soon as you rinse the tank thoroughly. You might be OK. I think a tiny bit of flash rust is OK for the kreme.

Leganto · « **Reply #20 on:** October 21, 2011, 09:56:47 AM »

Thanks for all of your help everyone.

I rinsed the tank with isopropyl alcohol...dumped it out....and then used a hair dryer to dry the rest.

I cleaned up the area around the holes...some are much bigger than pinholes.

I got some seal-all to try to fill them. After it cures a while, I am going to give it a go with Red-kote.

I am not going to spend anymore time or money after this on the tank.

So I will have to find a good used tank from a reputable source....or go for a fiberglass tank. I had better start saving money now.

Duanob · « **Reply #21 on:** October 21, 2011, 10:26:38 AM »

Ebay 550 tanks: These all need some work but make the owner garantee they don't leak.

http://www.ebay.com/itm/CB550-CB550K-Gas-Tank-Fuel-Tank-CB550-Four-MAKE-OFFER-?cmd=ViewItem&hash=item35b5e01ae1&item=230684629729&pt=Motorcycles_Parts_Accessories&vxp=mtr

http://www.ebay.com/itm/Honda-cb550-cb-550-four-gas-tank-fuel-?cmd=ViewItem&hash=item4cfaffeaba&item=330628590266&pt=Motorcycles_Parts_Accessories&vxp=mtr

http://www.ebay.com/itm/honda-cb550-cb550k-fuel-gas-tank-petrol-74-75-76-1975-1976-cb-550-four-1974-?cmd=ViewItem&hash=item56468f55d3&item=370550986195&pt=Motorcycles_Parts_Accessories&vxp=mtr

http://www.ebay.com/itm/1976-Honda-CB550-CB-550-Four-Gas-Fuel-Tank-?cmd=ViewItem&hash=item3a6bab9205&item=250914509317&pt=Motorcycles_Parts_Accessories&vxp=mtr

Leganto · « **Reply #22 on:** October 21, 2011, 01:58:52 PM »

Thanks for the links Duanob. Put em on my watch list until I know how this will turn out.

I put the red kote in after the seal- all had cured for 2 hours. I put half a quart in. It took a while to get everything coated. It bubbled up out of two more pinholes I hadn't seen before. I am going to let it air dry until tomorrow, then give it a second coat. I feel a little nervous about the holes I sealed.

If it will hold long enough to get the bike running, I will do a more permanent repair later.

And if it still leaks after two coats of the red stuff.....the time table will have to move up anyway.

Leganto · « **Reply #23 on:** October 24, 2011, 06:32:36 AM »

Here are some pics of the holes that the acid made as it converted the rust.

Also a couple of pics of the seal-all that I used to seal the holes.

And a pic after Red-kote.

fastbroshi · « **Reply #24 on:** October 25, 2011, 09:33:37 AM »

Quote from: Duanob on October 21, 2011, 10:26:38 AM

Ebay 550 tanks: These all need some work but make the owner garantee they don't leak.

http://www.ebay.com/itm/CB550-CB550K-Gas-Tank-Fuel-Tank-CB550-Four-MAKE-OFFER-?cmd=ViewItem&hash=item35b5e01ae1&item=230684629729&pt=Motorcycles_Parts_Accessories&vxp=mtr

http://www.ebay.com/itm/Honda-cb550-cb-550-four-gas-tank-fuel-?cmd=ViewItem&hash=item4cfaffeaba&item=330628590266&pt=Motorcycles_Parts_Accessories&vxp=mtr

http://www.ebay.com/itm/honda-cb550-cb550k-fuel-gas-tank-petrol-74-75-76-1975-1976-cb-550-four-1974-?cmd=ViewItem&hash=item56468f55d3&item=370550986195&pt=Motorcycles_Parts_Accessories&vxp=mtr

http://www.ebay.com/itm/1976-Honda-CB550-CB-550-Four-Gas-Fuel-Tank-?cmd=ViewItem&hash=item3a6bab9205&item=250914509317&pt=Motorcycles_Parts_Accessories&vxp=mtr

Dude, I don't understand how someone in good conscience could sell that last one. It looks like it has a layer of brownie in it.

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Author Topic: Prep and etch tank rust removal (Read 9680 times)