rusty gas tank

So on this tractor i bought, the guy swore he has been driving it regularly for 9 years. so when the tractor sputters and quits i check the sediment bowl and what do i find? spiders a leaf a bug and a bunch of rust/dirt. i look in the tank and the bottom is very dirty with what looks like rust flakes. This tractor starts very well. maybe half a pull on the starter, runs well and idles well, when it gets gas that is. what is the best way to clean out the tank? Help! 

Some people have used nuts inside the gas tank and bounce them around to remove the rust.  I have a rusty WD tank that I have been using electrolysis to clean the inside.  You can fill the inside with water mix with an Arm and Hammer solution and then put a scrap piece of metal on the inside and hook up a battery charger and it will pull the rust out of the tank and onto the scrap piece of metal.  It has been working really good, and it doesn't hurt the paint on the outside.  I would think you might even be able to do it with the gas tank on the tractor.  I took mine off.  If you want, I can put some picture of it on here for you.  I used to have some good links to it on my old computer.  I will try to find some for you to read.

I have an electric cement mixer that I strap gas tanks to and let them spin. I fill them with roffing nails and a length of small chain. I strap them on every way I can so it will clean all sides. Then I clean it out with air then parts washer.

Interesting idea Thad. How do you do tanks if they got a baffel in them? I cant see you getting the nais out of both sides or being sure its clean.

The key to the process is to keep it going and running and then when done, clean the tank out and dry it and then put something in there to keep it from rusting until you fill it up with gas.  There is some acid etching solution that you can buy from Home Depot by Krud Kutter, called Must for Rust.  It etches the bare metal and when dry protects it from rusting again.  When I am done with my tank, I am just going to put some of this in there and swish it around and dump it out.  Here is the pictures of my tank.  I put an old piece of conduit in there, and put a roll of electrical tape around it to keep it from touching the sides, as the two pieces of metal can't touch. 

One thing be sure you do....make sure there is a riser that sits at least 1/2 inch up into the tank (allows for rust and stuff at least that deep) I found a button off of someone's coverals in mine once , and yes, it drove me crazy!! Run then stop, run , then stop...

I have used the piece of chain and roller it around for a while, but not long enough. I will be doing it again hopefully before garden time gets here. I was looking at POR 15 online. They offer a kit that has the acid/cleaner to remove the rust and varnish, an etching and drying agent to get all of the moisture out and prime the metal, then the POR 15 coating to seal and coat everything. It is supposed to be a special kind of coating that will never come off or get brittle, soft, or eaten away by gas and additive chemicals. Water is supposed to make the coating "set" harder. I'm thinkin of trying it. I like the electrolysis idea Chuck, seems like less work anyway. Can you give me a few more pointers on how to mix the water, laundry soda, what amp battery charger you need, and so on? Did you put anything in the bottom to keep the conduit from touching the metal bottom of the tank?

I'll vouch for that POR15 kit. It sure would be nice to get the rust out first with Chuck's method.

thanks so much for the pictures. i got the tank off just a second ago. im thinking what i thought was rust might be a hevty dose of dirt. the gas cap is loose so who knows how much dirt might have found its way in. im going to pressure wash it tomorrow and what doesnt come out with that im going to try the battery charger trick. in fact im filing that trick away for when i restore the wd 45.

Very interesting discussion. 

I went the POR 15 route on mine.  First I cleaned it in a parts washer, then a power wash.  Followed this with the POR system.  It takes some time to ensure the entire inside is cleaned with the cleaner and then prepped.  POR 15 adheres to anything it touches when it drys, so make sure that there are no plugs left in the tank after you drain out the left over POR.  I had to run taps in the fuel outlet to clean it up.  Haven't used the tank yet, but have used the PO 15 exterior coatings and they sure are hard and impervious. 

I used the POR-15 kit on my one-seventy tank.  After I turned it up to pour out the excess coating I used Q-tips to clean the POR-15 off the threads where the sedement bowl attaches.  Worked good.

  if you need to use   put a riser in the tank 1 1/2" --2" high  an go on about your work

In an earlier post, I think Allen Dilg had suggested wrapping a sediment bowl screen up like a cigarette and sticking it in the upper threaded stub of the sediment bowl to function as a riser. Like Gary's idea, it drains the fluids and catches the chunks.

 Just make sure that the battery charger is the old type and not a digital one as I was told that those do not work for electrolysis. 

If off the tractor, run it to a good radiator shop and have it acidized; they can perform this on the inside only and save your original paint if they know what they are doing when they "bung" it up.