Rust in gas tank

Sun Jun 30, 2013 1:26 am

Andy here from the UK.

I have drained old gas from by 1948 Cub. There is relatively superficial rust inside the tank.

Before replenishing with fresh gas I would sure appreciate any suggestions to address this effectively without need to remove the tank.

Re: Rust in gas tank

Sun Jun 30, 2013 1:32 am

Is the rust coming off in pieces? If so, how big are the pieces?
If its just a few spots the inside of the tank with nothing breaking loose, you will probably be ok with running some 2 cycle oil with the fuel.
If its coming off in pieces big enough to stop up the fuel bowl screen, then I beieve you'll have to pull the tank for some aggressive treatment.

Re: Rust in gas tank

Sun Jun 30, 2013 2:06 am

Thanks for the swift input Raymond.
Any loose rust is in 'grit' form rather than significant flaking pieces. This is why I am hoping to get by with leaving the tank in place. My idea is to remove detritus by vacuum cleaner.
I have some bulk water based rust treatment solution (of US manufacture) I have used successfully to treat implements before painting. Would it be appropriate to spray some inside the tank? Then of course leave to dry thoroughly before replenishing with fresh gas.

Re: Rust in gas tank

Sun Jun 30, 2013 5:35 am

I'm not familiar with this rust treatment you're referring to, but NEVER, NEVER EVER USE A VACUUM CLEANER TO CLEAN A FUEL TANK! The fuel vapors get into the motor of the vacuum cleaner and cause a nasty explosion! I think that if you need to clean the tank, you need to bite the bullet and remove it.

Re: Rust in gas tank

Sun Jun 30, 2013 6:44 am

If it is flakey rust, I use a dish soap, hot hot water and a hand full of 3/8" hex nuts. Throw it all in and shake it really well and when I think I am done I drain it all and use an air hose with a rubber hose to blow the rest around and rinse again and again. I have done this a few time with the cub tanks, it can be rather hard since it is so awkward. When done I coat with 2 cycle gas and oil and reinstall. I have yet to redo any of the tanks I have done.

Good luck

Re: Rust in gas tank

Sun Jun 30, 2013 6:58 am

POR-15 and RedKote are two sealers for gas tanks. But the tank has to be removed before the sealer is used. Search function, utilization of both products have been discussed on this board.

Re: Rust in gas tank

Sun Jun 30, 2013 8:13 am


As Gary said - Never Ever Use a Vacuum Cleaner anywhere near a gas tank!.

I am not sure what you have across the pond, but I ensure all of my tanks have been taken care of by professionals. My local Radiator/Gas Tank Repair Shop does all of my tanks. I had Ellie's tank done almost 10 years ago now and it is still as clean as the day I got it back from the shop. They use a product called Red Kote.


I just had Granny's tank done over the winter and I am very pleased with the end result. You should check with a local shop, bite the bullet and get it done. Then the issue will be solved and won't bug you again. I would strongly recommend it.

Re: Rust in gas tank

Sun Jun 30, 2013 8:53 am

On the other hand, if there is just a little superficial rust and the fuel in the sediment bowl doesn't look rusty, just ignore it.

Re: Rust in gas tank

Sun Jun 30, 2013 9:44 am

My suggestion would be to remove and clean the sediment bowl. Then watch and see how quickly rust particles accumulate in it. If slowly, leave the tank as is; if quickly, remove the tank and choose your method of rust removal and sealing. The decision you make may also affect how often the main jet in the carb needs to be cleaned out too.


Re: Rust in gas tank

Sun Jun 30, 2013 5:55 pm

My Farmall "H" aka Brutus had loose rust in the tank even after cleaning. The fine grainy stuff was just enough to cause headaches going thru the fuel system. I had a old 100lb pull magnet that was made for a welding ground connector, but the connection was twisted off. I slaped that on the bottom of the tank on the outside in outa way place and all the grainy lil boogers go hang out there now. Not in the sediment bowl or float or other fuel system locations.I know I need to take tank off n get it cleaned n coated soon but the magnet holds it so I can use the tractor till then.

Re: Rust in gas tank

Mon Jul 01, 2013 1:22 am

Very grateful as always for the helpful responses.

I have cleaned the tank as best I can - without causing an explosion! - sprayed inside with carb cleaner and replenished with fresh gas. Removal of the tank and adherence to your suggestions can wait another day.

In the meantime use of a magnet seems a sensible option - thanks!

Soon to collect another 1948 Cub from France - will check out the gas tank situation - may have to follow your advice sooner than anticipated!