I thought that when I lived in the San Francisco are we had a rust problem but when I moved to the Philippines I found out all about what rust is!!! WOW!
Our favorite saying is "rust never sleeps". Amen, brother.
A few months ago, I found this product called "rust converter" whatever that's suppose to mean.
It's a plastic one litre bottle and the clear liquid is very heavy in weight but very thin pouring like water.
I tried this stuff on some rusted metal (not hard to find around here) and to my amazment in a few seconds the rust turned black in color!! No signs of rust anymore!! GONE!!
I kept an eye on the part and after a week or so, there was still no signs of rust.
I tried to paint over it and there was no problem doing so!
Next I tried it in a rusted gas tank. I put it in straight and turned the tank over and over for about 15 minutes and then emptied the tank and let it "air dry" for 2 days. The rust inside had turned black in color and rust was gone!!
Since then. I have done several tanks for freinds. The ones that had more than surface rust, I flushed with acetone and small rocks to loosen the big stuff before I applied the solution to the tank.
I have no idea of what the chemical is because there is only a small paper label on the container.
I got this stuff from a paint store so maybe if you talk to them, they can fiqure out what it is.
All I know is that this stuff works great and is a hell of a lot easier and cheaper to use rather than those "tank liners" at the bike shops.
Three bucks in US Dollars!!
I was going to post this in the Carb section, but I think that more will see it in this one.