The Cessna 120-140 Association Forum

I have a problem. Found a really really low time 46 Cessna 140 that has been sitting for a long time with car gas in the tanks. How can I clean these tanks? I have removed the gauges they were in horrible shape but are repairable and wonder about getting the rest of the crud out of the tanks. There is not a lot of heavy thick residue in there but they really need to be cleaned.

Put some gas in them, shake the wings and drain it out. Repeat.

Just a thought, not sure of any problems using it, but this with some mineral spirits. Let it all drain out the sump hole? If you have the gauges out then you have some maneuvering room. I use this every now and then on my engine with a 5 gallon bucket of mineral spirits. Vapor mists, static electricity, and all the other precautions to apply....

https://www.harborfreight.com/engine-cl ... 68290.html

...not much to add to above excellent suggestions. If any way possible, you'll probably want to determine if there's been any "sloshing compound" or similar "sealer" added to the tanks at some point in history -- some of that stuff has a way of letting go in little "strips". I use a lot of Wally World carb cleaner (a LOT) on various projects, from cleaning the floor, fighting fire ants, engine parts cleaning to degreasing metal for paint prep...and, much more. I'd want to consult John, Randy, Dave or others who are likely to know if the carb cleaner may be too harsh for the thin walled tank...but, the cleaner is cheap (relatively speaking), may well be no more "corrosive" than avgas(?) & you could reach all around via spraying through the fill & gauge holes...of course, drain through the quick drain hole (then, as Randy sez, "repeat"). Dave's admonitions re safety certainly apply here, too. In any event, I'm betting that you'll find the best method(s) and reach a point that you can feel confident that the auto gas gunk is gone! Keep us posted. Mac

Thanks for the help Will let you know how it goes +BTW this 140 has less than 650 hrs.

4280 wrote: ↑Sun Sep 02, 2018 8:36 pm

Thanks for the help Will let you know how it goes +BTW this 140 has less than 650 hrs.

Wow! That really is almost "new" -- great find! Do keep us posted and share pics as you can. Mac

Hi,

I had the same problem. My mechanic suggested that I drain the tanks, disconnect the fuel lines and add E85. Let it soak, drain, repeat. The alcohol breaks down the varnish and allows it to disengage from the aluminum.

Under his supervision, I performed a number of cycles (I think I did it four times per tank). I power washed the tanks several times too to help break the loosened varnish free. You have to let the E85 soak for several days during each cycle so the plane will be out of service for a while while you do this.

Also, I pulled the fuel gauges out of the tanks and made up blanking plates with gaskets to cover the holes during the process.

It’s a massive pain to do this but it worked!

Good luck.

Mike