The Stovebolt Site Forums The Shop Area Engine Shop What is meant by boil out a gas tank?

Well I picked up my gas tank from the radiator shop today and I can't say I am very happy with it. I didn't look at it very close until I got home but when I shook it I could hear a rattle. After several minutes of shaking it I got a screw to fall out of it. I am not positive but pretty sure that screw wasn't in there when I dropped it off. Also several ounces of brown water poured out of it. If I wipe the inside with my finger I can get white chalky stuff to come off. It took about 5 times of rinsing it with a few ounces of gas to start getting gas to come out that wasn't red rust colored. The tank was in great shape when I dropped it off, just a little dirty inside. I probably could have rinsed it out myself and used it and saved $90. I was temped to do so but I thought I would avoid problems of a plugged filter and carb and just have it done by a pro. I had this done years ago on a much newer tank and what I remember was it came back looking almost brand new. I am really not sure what is involved in the boiling out process. Were my expectations too high or did I get a poor done tank?

You got a bum job. Radiator shops used to use some very caustic cleaning solvents in heated "boiling" tanks to dissolve the deposits in copper-based radiators. They didn't actually boil the stuff- - - -it was heated to 190 degrees or so. Those chemicals got scarce, expensive, and tightly controlled by the tree huggers and other environmental whack jobs some time ago, so getting a radiator or gas tank chemically cleaned is just about a thing of the past. Aluminum radiators would just sort of disappear in a caustic tank, so most shops have gone to some sort of detergent-based cleaning solution these days. That stuff is pretty much useless for getting rust out of a gas tank. Use a strong mixture of Sani-Flush toilet bowl cleaner and very hot water to do your own cleaning, then flush it with several rinses of water. You'll probably do a better cleaning job than the radiator shop- - - - -just don't tell anybody where you dump the stuff!
Jerry

Thanks for the reply, thats good to know. I should have known something was up when I took the tank to my local guy whom I talked with about doing this job for me 6 months ago and he was closed. So I ended up taking it to a little hole in the wall shop and hour away in the rough part of town. When I got there to pick it up and give him a check I was told cash only. I think he is on his way out of business as well. Its just irritating and a little depressing that people say they can do something for you and end up doing a horrible job. Not completely his fault if the chemicals are scarce but still. I will keep the toilet cleaner idea in mind. I may just use the tank as is for now and make sure to put a small micron large volume filter inline before the pump and change it out after a few tanks.

Thanks again

Good chemicals are so watered down these day, you cant kill a bees nest effectively or moss on the roof for that matter.
Hell the carb cleaner you buy it isnt half as good as the stuff you could buy a decade or two ago.

Muriatic Acid is the good stuff. Its a pool chemical that eats rust, and if not properly neutralized, good metal. Available everywhere. Its pretty bad stuff. Avoid it possible.

You'll probably want phosphoric acid. Much tamer, wont hurt good metal but will convert rust to a harmless oxide. You want at least a 30-40% phosphoric acid product. just wash it out with water. No need to neutralize it.

I believe radiators shops used or still use sodium hydroxide (lye) to "boil " out the radiator. The lye removes grease and some crud but hard deposits might need to be physically removed ....Lye will corrode aluminum radiators...You can do this at home, some hardware stores still sell lye for cleaning plumbing pipes. Lye is obviously cause severe burns, you need face and arm protection.Lye will not corrode steel so it can be used in a fuel tank...I have used muriatic acid on old radiators and fuel tanks...Again it nasty stuff ... Some or all fuel tanks are galvanized inside to inhibit rust...The coating breaks down and rust will likely return..