Whats the best media for fuel tank

[gumby302ho]

 I have suffered a pin hole in my fuel tank, I never expected this as my tank is super clean when looking inside it. I am going to epoxy it with a caswell product. They say throw some drywall screws inside to help clean the inside but the way the FJ tank is I am afraid the screws will get stuck in the tight seems so I was wondering if anyone has found a good media to use inside the tank that wont get lost in there. PS the float level sending unit was a little tricky getting out.

[Motofun]

+ 1 for the Caswell epoxy, the best stuff I've found for this purpose.  It helps to rough up the interior of the tank to give it some "tooth".  I used drywall screws with good success, took a little patience to get them out.  The easiest way was to fish them out from the bottom of the tank via the petcock opening.

[CutterBill]

I've heard of people using all kinds of things to mechanically abrade the rust out of a fuel tank... lengths of chain, nuts and bolts, and now drywall screws? Seems a bit "caveman" to me. May I suggest using vibratory media. It is specifically designed for this purpose and comes in various sizes, grits and hardness depending on the job at hand. Here's just one link... https://www.mcmaster.com/vibratory-finishing-media/

The other question I have is just how are you going to vibrate/rotate the fuel tank? Are you planning on just shaking it by hand? I would think that would take quite a while.  I heard one guy wrapped his tank in towels and blankets, then put it in his clothes dryer (no heat) and let the dryer run for half-an-hour. He claimed it worked.

And I hate to be so negative, but pinholes don't occur in just one spot on clean, sound metal. Your tank probably has a largish area that has rusted away until it is very thin. The pinhole you see is just the thinnest part of that rusted area. So you need to think about some sort of coating that will cover the entire area. I've never used any kind of epoxy but I suppose it would work, if properly applied.

Tip: Borescopes have become really cheap; I bought one at Harbor Freight that works very well. Think I paid $50.

Obviously, the very best solution would be a clean, un-rusted tank with a new paint job but that's expensive.  So back to sealing your tank... do a Google search on Mil-S-8802 Fuel Tank Sealant. This is what we use on aircraft use and it is truly wonderful stuff. Sticks tenaciously and is impervious to fuel. Properly applied, it will last 30-50 years. If you go that route, PM me for tips on what type to use and how to apply it.

Hope this helps,
Bill

[red]

I have suffered a pin hole in my fuel tank, I never expected this as my tank is super clean when looking inside it. I am going to epoxy it with a caswell product.

Gumby,

The best idea I've heard for "media" is to use a very thin cheap chain.  I like CutterBill's idea of a well-padded clothes dryer as a tank tumbler, too, but I would not use that idea unless there is a "no heat" option for the dryer.

Electrolysis is the best way to kill any remaining rust specks.  Looks complex, but it's just a battery charger, scrap metal (NOT stainless steel), and some slightly tinkered water.  You can find lots of info on that process.  Here is a little:

https://www.stovebolt.com/techtips/rust/electrolytic_derusting.htm

You will need to coat the inside of the tank, certainly.  Some internal tank coatings work, and some do not.  The application process is critical with them.  Read up on these coatings, before you pick one.
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