toilet bowl cleanr hydrogen chloride to clean tank

Saw the other tank cleaning thread but this is a question and didn't want to hijack that one.

I have a 1976 kz900 and am about to clean out years of varnished-up gas. The PO left a bunch of gas in the fuel tank and it is varnish-city. There's rust in there too.

He told me to flush it with water and gave me a huge back of sharp-edged rocks known as 'tumbling media' used in commercial tumblers for coarse cleaning, shake the tank really good with those inside.

THEN -- after the loose stuff is off -- remove the tumbling media, flush the tank with water, and he gave me
TOILET BOWL CLEANER that is 20% hydrogen chloride.

I was dubious about that but he showed a gas tank he had done -- MAN-OH-MAN the insides of that tank LOOKED BRAND NEW.

His process was to plug all holes, then rest the tank overnight on one of its 4 sides, then rest it on another side, 4 nights in a row.

Is toilet bowl cleaner, aka Hydrogen Chloride, a good idea?

Hydrogen Chloride AKA Hydrochloric Acid, AKA Muriatic Acid, Is used by most of us and most radiator shops. You can buy Muriatic acid at he Hardware store in One gallon bottles for a few bucks. Once you have removed all the "Greasy Kid Stuff" From the inside of the tank it will take only a few minutes to remove the rust with Muriatic acid. This is nothing new or no new revelation. After you are done with the HCL rinse it out with water than water with a little baking soda. Than rinse it with a little Phosphoric acid to preventing it from rusting further.

otakar wrote:

Hydrogen Chloride AKA Hydrochloric Acid, AKA Muriatic Acid, Is used by most of us and most radiator shops. You can buy Muriatic acid at he Hardware store in One gallon bottles for a few bucks. Once you have removed all the "Greasy Kid Stuff" From the inside of the tank it will take only a few minutes to remove the rust with Muriatic acid. This is nothing new or no new revelation.

whew, hydrochloric acid, okay, question then is how do I 'stop' it?

Correct me if I'm wrong but if you don't 'stop' acid it will keep etching and I would think I'd end up with holes.

It sure is *tempting* to use it. I tried to clean a tank using Naval Jelly (phosphoric acid) and it did not clean the tank. The gas tank he treated with the toilet bowl cleaner was *spotless.* I used the naval jelly because I was told you can 'stop' it from etching by just flushing with water, which I did (but the jelly didn't clean the tank).

How do I 'stop' the hydrogen chloride? With baking soda?

Just flush it with water afterward.

Believe it or not, HCL reacts with virgin steel very little it however reacts with "Iron Oxide" vigorously. This means that once the rust is eaten away the affect of the acid is quite mild on the clean steel. Do an experiment with an old rusty nail. Make sure that it is not a "Galvanized" nail because the acid will have a strong reaction with the Zinc.

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I use it right out of the bottle.

Getting ready to do my tank.

So, what does one use to close the holes in the tank when using an acid wash? I've heard simple duct tape, but that wouldn't seem to hold with HCL.

Also, have the fuel level gauge and cap rusted on pretty bad, have to figure out how to remove them first. Can't turn the screws/bolts. Broke one off. I've used all the penetrating stuff to no avail. Now thinking I'll drip some HCL on them and see what happens.

btw, what does HCL do to chrome?

I know to avoid using it on aluminum, of course.

HCL removes Chrome down to the Nickel. I make block-off plates out of Delryn and use rubber seals. The cap I use a large rubber stopper.

KAHruzer wrote:

btw, what does HCL do to chrome?

I know to avoid using it on aluminum, of course.

If it's anything like battery acid, it will mess chrome up good.

It's probably a good idea to get the fuel sensor removed.

If you want to try something a bit milder than HCL, then look for some Tile & Grout cleaner at the home stores, but make sure it contains Phosphoric Acid. Use your tumbling media with the acid. I seal up the petcokk holes with some wood and rubber, and with Phosphoric acid you can use duct tape on the tank filler hole. If you use HCL then you may need to get an expanding rubber plug that fits, sometimes called a "freeze plug". It would hold up better than tape.

Throw the acid and rocks in the tank, seal it up and shake like hell. When it's clean just rinse it out and remove your rocks. Instead of rocks I use a chain, it's a lot easier to fish out later.

If you put rocks into the tank, make sure that they are not any form of lime stone. They will react violently with HCL. I use a section of chain instead of rocks. But you should remove all the loose stuff first with just water and some Ammonia before you use the HCL to remove the rust. You should not require anything besides the HCL in the tank to do that.