and secondly do you coat them to prevent future problems?
What do you do for rust? What do you do for varnish? Same thing for both?
What coating products do you use if any?
I myself have filled a nasty tank with battery acid before, drained, flushed with water, and then coated them, I have used both the POR 15 fuel tank coating and the Bill Hirsch stuff. so far so good.
the only problem I see with the battery acid soak is that I feel a need to rinse them out after I pour off the acid. Problem being is that they start to flash rust again IMMEDIATELY. As SOON as they are dry I would have to use the POR or Bill Hirsch stuff to seal them from further damage.
Once I took a 3 qt tank from a 5HP Briggs horizontal, the kind that the carb mounts directly to, over to a local radiator shop. he charged me $25 or 30 to steam and coat that tank. I do not know what product he uses. but when I can buy a qt of sealer for that same $25 and coat several tanks myself with that quart, I think I'd be stupid to send them off....
I have heard great things about a product called "Red Kote" but have not tried that yet. I see that OReillys even carries that stuff.
I once used product called "Kreem" a 2 part process on an old Honduh motorcycle but I have heard a lot of complaints about that particular product, peeling and clogging the fuel line. I didn't have that bike around long enough to find out.
I have a 6 qt tank that I want to try it on but I 1st need to clean it out of all the left over varnish. I had this tank given to me about 3 years ago and I am just now wanting to use it.... but its obvious that it sat with old bad gas in it at one point in the past.
What ideas are out there besides the battery acid for cleaning out the innards?
I'd like to carb a que it and see what that does/ but instead of filling a can to put on the stove to dunk a carb into, I'd have to fill the tank itself and put the fire right to it for the "boil" part.... I am not too worried about fumes because the water/ lemon juice would displace any gas fumes///// and as long as this tank has been sitting (a few years, dry, in the attic) that would tend to vent them too... though as soon as I pulled the cap it smelled of varnish...
so that's why I'm asking what you guys do with your old metal gas tanks that need cleaned out...