What's the best for cleaning rust out of tank?

[GG]

Glenardo - I live in Guadalupe, northeast side of San José. GG

[e3steve]

Okay guys - thanks for the tip. Sounds a bit scary, and I don't know what "washing soda" translates to in Spanish. I'll give it a try! GG

Sosa, or sosa de lavado?

[Glenardo]

Arm & Hammer LAUNDRY Soda, also known as washing soda.

Here's a great site that discusses the different options on gas tank rust.

http://www.mopedarmy.com/wiki/Removing_ ... a_gas_tank

I started my gas tank treatment. Put in some Simple green, hot water and a handfull of old bolts nuts and a short piece of chain. Danced and shook it for 30 mins, drained and flushed w/ clear water. Out came some nasty brown water!! Now I have the Evapo Rust soaking overnight.

GG. I didn't spend too much time in San Jose, mostly passing thru while traveling around.

[GG]

Hey everyone - the advice to try the electrolyte de-rusting method is right on. I basically followed the guidelines and the website mentioned in this post. I used baking soda instead of carbonite, and it worked just fine. I used my large battery charger, and put it a notch up from the lowest. I burned up a coat hanger, and changed the water three times. The rust patches (which were many, and deep) have been fairly cleaned up completely, and leaves a dark spot. I followed up with a half bottle of naval jelly that I had left over, cleaned everything with a good shaking of nuts and bolts, dried the tank and put a good epoxy coating inside. It seems like it's like new. I recommend the procedure! Just make sure the hanger doesn't touch the tank (I used a piece of radiator hose fit inside the opening, and bent the hanger so it didn't touch inside.) The rest is just let 'er boil!

GG

[Glenardo]

I thought I'd update my results w/ EvapoRust.... It works!!!

I did the usual; wash, shake w/ hardware, rinse and then let EvapoRust soak overnight. Then I would rotate the tank and soak again I did this for about a week and then rinsed and washed w/ Isopropyl alcohol and gas. And the tank is clean!!! Like I said previously I only had light surface rust, nothing major or deep. It's not the quickest, but it's safe and easy to use.

[Snakeoil]

I tried the electrolytic process with washing soda. Seems like a lot of work and mess for mediocre results.

I'm a firm believer in Phosphoric Acid. You can buy in in autobody stores as Metal Prep. Some hardware stores sell it under various names, all rust removers. Just read the contents label.

Process is pretty simple. Time depends on how bad (meaning deep) the rust is.

First step is to clean out all the old crud. For that I start with a handful of sheet rock screws. These act like tiny little files and chisels and I've found them to be more effective that nuts and bolts, BBs, chain, etc.. Put them in and do the cha-cha. Dump out, along with all the dry disgusting crud, put the screws back in and have another go at it. Continue until you have most of the ugly deposits removed. This should also take out all the major rust scale if you have a seriously rusted tank. The screws will also manage to find the areas where the rust has not eaten thru the paint yet, but has eaten thru the metal. I did an S90 tank that looked great on the outside and pretty good on the inside. Screws found areas I could not see and actually punched thru the rust and the paint to reveal 6 pin holes in the tank.

Next step is the clean the tank with mineral spirits and the same screws. This gets the remaining crud out and helps flush out all the powdery stuff left inside. I pour the min spririts thru a coffee filter and repeat a few times until the filter looks pretty clean.

Then set the tank in the sun or in a warm place to dry.

Now, if the screws found pin holes, tape over them on the outside to keep the phos acid inside and not one your floor.

Once dry inside, pour in a sufficient quantity of phos acid. Do this outside because the fumes will stay in your nose and ruin your dinner. You can reuse the acid almost indefinitely, so no need to be frugal with the acid. Slosh and let it sit while you do something else. Slosh it every so often to keep the surface wet with acid. Depending on how badly it is rusted, you will start to see the rust be eaten away. The phos acid will not eat the good steel, only the rust. Leave it in overnight if you want for heavily rusted tanks. When you are done the inside of the tank should be a dull gray everywhere, including the rusted areas. All the rust should be gone, leaving just pits behind. Pour out the acid, leave the tank upside down to drain well (remember, save the acid for the next tank). If you let the acid dry, it leaves behind a zinc coating that prevents flash rust from occuring. When it has dried, flush it out with alcohol.

If you are going to seal the tank, chances are one of the products included in the tank sealer kit is phos acid. Make sure you follow the rest of the sealer kit instructions and you should have a leak free tank.

I've used this same process for tanks that had a little rust staring, but did not need sealing. The rust never returned.... at least in the last few years.

regards,
Rob

[Wilf]

Rob,

What strange alchemy "leaves behind a zinc oating" when you let phosphoric acid dry on steel? There is no zinc in the acid or the steel.

Wilf