Aluminum Gas Tank Cleaning

[therrick]

I've searched the archives here - specifically, the threads that relate to fuel tank cleaning - but found no definitive information that relates to my situation.

According to Mark Toland, I've got one of five C-Dorys made in 1984 that have a 28 gal. fuel tank under the V-berth. The previous owner (maybe 10 years) never used it, and I have no idea what the original owner did. I've pumped out the old gas and water and a bunch of crud, but much work remains. I pulled the fittings from the tank and the copper line that sucks fuel from the bottom of the tank was coated in about three-sixteenths of an inch of grot.

I've never done anything like this before; that is, cleaning an aluminum gas tank. And, to make things more interesting, it's not coming out of the boat. It's epoxied to the hull and the only thing that's going to get it out is my monster crow-bar; then everybody loses... So, I need to clean it in place. I've only found one article on the Internet after quite a search, and he used acetone. Of course he had the tank removed and was able to slosh it on the ground. He said he used about 1/3 of a gallon at a time. Overall he used about 2 gallons of acetone before he considered the tank clean enough to use.

I could rock the boat on the trailer and use a cheap pump to remove the bulk of acetone and grot; that may achieve something like his results.

So, anyone ever done this before? Got ideas? The only given is that tank stays put. All other options are on the table.

Thanks folks...

Tom Herrick

[Sea Wolf]

therrick-

I can't find anything on The Hull Truth, which may be one of the most comprehensive sites around.

If you can't find it with Google, maybe you ought to pose the question to some aluminum gas tank manufactuers.

Maybe there isn't any really good way in your circumstance with captive embeded tanks to do it?

I'd certainly add a Racor 10 or even 2 micron filter in line if I did think I'd cleaned it out pretty good somehow.

Maybe we need a chemist of the right type and experience to advise us on this?

You might try posting it on The Hull Truth, as they have up to about 500 folks on line most of the time, and some pretty good technical people.

Good Luck!

Joe.

[Larry H]

Tom,

I would start by pouring 1/2 gal of acetone or so into the tank, and slosh it around. Since the tank is in the boat, tow the boat around, stop, start, and turn. Then pump out the acetone and see if it is dissolving the crud. Repeat as needed.

Other solvents that might work are alcohol (97%) or gasoline.

As all of these are flammable, be careful.

As Joe said, put on a good filter before using the tank.

[AstoriaDave]

Before the acetone or any flammable solvents, consider almost-filling it with hot water laced with a quarter cup of Dawn (yes, the dishwashing detergent), and run a steam hose in one opening and an exit hose out each remaining orifice. Agitate and heat with the steam until it looks like the effluent is running reasonably clean. this could take a while. Empty the tank and flush it with a couple tank-volumes of clear water (steam will help here, also).

Then run a couple one-gallon-size acetone rinses through there, agitating best you can. Finish with a couple rinses of white gas or unleaded to remove the acetone and residual water.

Definitely keep a Racor inline for a while.

[therrick]

Slightly different story now. I found that the tank was not epoxied in, but bedded with a polyester resin. Light work with my flatbar popped the tank right out. I poured out about a gallon of rust-colored fuel and water from the aluminum tank.

Joe, I posted over at THT and have received some responses as well, but none so clear as those from Larry and Dave here. My wife will pick up the latest PassageMaker magazine to get the article on tank cleaning.

Thanks, Dave for the Dawn suggestion. It's good stuff; I've used it for many things besides dishes. My tank will smell like apple blossoms when I'm done; much better than the original Dawn. I'll start there then move on to the acetone until it runs clear. Then dose it up with alcohol to remove any water in the tank. Planning on using a 5-inch hole saw to cut an inspection port then using my 6-inch saw on sheet stock for the cover plate. Some gasket material and self-tapping screws should do the trick there. Also will add a fuel gauge sending unit to the tank; can't understand why there wasn't one originally.

Looks like I'll be taking a much longer trip through the Kentucky River lock system this fall with the larger tank.

Thanks to all for your help. Nice place you've got here...

T

[oldgrowth]

therrick - fill your tank with water before you go cutting a hole in it. If you have gas fumes, acetone fumes or other volatile fumes, you could end up with an explosion.

[therrick]

Thanks, Dave. It's an aluminum tank though. I didn't think that that material would emit sparks - unlike steel. The damage is done however, and so far I think I'm here to post about it. Of course, I could be just floating in the ether dreaming about posting to the C-Brats Web site. We'll see tomorrow...

I seem to remember that I managed to saw a 5-inch inspection hole in the center of the tank, not quite missing the single baffle. But after a little peening here, and filing there I've got a nice access into the larger of the two chambers. If I'm here on Monday I'll fit it with a 6-inch cover and open up another hole for a fuel gauge sending unit.

The tank wasn't nearly as gunked up as I originally suspected. The fuel pickup tube is of copper which oxidized quite a bit and tainted the fuel/water mixture I dumped out. The inside of the tank is only slightly varnished. I'll first use some acetone on a rag to see how it cleans up in one area, then if it needs it I'll do a tank rinse or two or three and see how it goes. Inspection port - nice idea...

Anyway, your original point, Dave. Is it possible to set off sparks using a bi-metal hole saw on aluminum? I thought it wasn't but if it is, I'd like to avoid checking out that way.

Thanks,

T

[AstoriaDave]