Big 20 Gas Tank

Not sure if POR-15 will fill the dimples but I've been very impressed with it as a primer over rusted metal. I used it on some rusted gate posts when building my entrance gate. The posts had pitted surface rust that gave the post a rustic look. I sanded them, wiped them down with a thinner, and then primed them with POR-15. They have been in the elements for 8 years now and there is no sign of any rust returning. I will definitely use the product again.

I always have just cut the bottom sheet metal out that was bad and welded in new metal. Never had a problem by doing it this way. Otherwise. vibration and additional age will result in a future failure of the tanks bottom.

I cut the bottoms out and replace them. This allows to clean the inside of the tank also. I cut along the weld seams and clean and reweld. When done the tanks look as they did when new. You would not know I cut and repaired it. I do not use sealer inside the tank. I pressure check and the make sure they are welded correctly. The sealer breaks down with the newer gas and plugs up the fuel system and the only way to get it out is cut the tank open and sandblast the inside. I used to do vintage car and truck tanks for customers and seal them but the sealer became a big problem. cut out the bottom piece and weld in a new.

I replaced the bottom in my "CAT-28" tank, cant tell it was replaced and gave me a chance to sandblast inside of tank. I just finished replacing the bottom of the fuel tank on my Rd-6. I had a shop roll a new bottom and just cut the welds and rewedded in the new bottom. I did fill the tank with exhaust gas from my lawn mower, just to be sure.
Good luck
Frank👍

Welding in a new bottom on the welded steel type tanks is a great way to fix them! The big 20 however has a rolled and soldered tin type gas tank, so welding in a new bottom is not really possible. I have had good luck soldering up the pinholes on my tin tanks. I suppose you could solder a patch on the bottom where nobody will see it. Caterpillarman

Automotive body repair guys used solder to fill pin holes and dimples on automotive sheet metal. If it was cleaned well, you could probably do the same with it.

Do all CAT-20's have tin gas tanks, I don't know? I thought some had heaver tanks like my Cat-28? I also did the bottom of the gas tank in my CAT-22. If it is a "tin" tank then you could just solder on a patch or solder in a new bottom like "CATMAN" said.
Frank👍

Hello, All Cat big 20's have the tin gas tank. The little 20's have the welded steel tank like a 22 and 28. Caterpillarman

Thanks for the information Caterpillarman. I learned something new today.
Frank👍