Technical What is the best way to clean old gasoline sludge from a Model A gas tank?

I have a 1929 roadster that has not been started up for about 1 1/2 years now, and while shining a light into the stock gas tank I noticed that the small amount of remaining gasoline has now turned into a gooey sludge. What is the best way of removing this sludge from a stock Model A gas tank? The gas tank previously has had a liner put on the inside and I'm sure there are a significant amount of baffles inside a Model A gas tank as well.
I would like to remove this sludge from the tank without doing a whole lot of damage to the gas tank liner.
I'm quite sure others on here have run into this problem, and what did you use to get rid of the old gasoline sludge?

 

denatured alcohol for old gas. then, rotate on a cement mixer with crushed gravel and some soapy water to make it sloshy. spotless clean in a day or two, then dry it and vacuum out the rocks

 

Denatured works great. We hung the tank on chains and pushed it back and forth and rotated it. Dumped and repeat. Tank came real clean. Used a small chain instead of rocks

 

I will never use one of the tank sealers again, on the way to the nationals in Columbus,Ohio the liner started to break down and started stopping up the fuel filters, we changed 6 on the side of the interstate and when we arrived at the motel on Thursday afternoon we pulled the tank and with the help of a local to the area we found a radiator shop that could hot tank it and clean it out as clean as a pin.

I realize if you remove the tank and hot vat it the paint on the outside of the tank will be toast so the denatured alcohol is probably your best bet. HRP

 

I had the same luck with a “sealed tank” as well as @HOTRODPRIMER had. My case was OT vehicle, but at the time an aftermarket tanks were known not to fit well. So off to the radiator shop to have them cut it apart, clean it out. They called and talked me into sealing it. 3 years later the stuff was causing issues. Pretty much soured me on that stuff since.

 

Yup, alky and NO SEALER

 

I use lacquer thinner. If there is any way to get inside the tank I wire a rag on a stick and mop the glop.

 

Alcohol, lacquer thinner, and acetone all work quite well. If you end up with pin holes... repop tank is the way to go.
Depending on the style of your build, use an aftermarket tank mounted elsewhere in the car and just use the visible part of the old tank and cut the back side out of it. That opens up a whole lot of behind the dash space for what ever you want o put there.

 

Best way since the Model A tanks have baffles is to have it taken apart, cleaned, then welded back up. No questions, no plugged fuel filters, no breakdowns from plugged fuel system, no worries.

 

Is this a running driving car? If so leave it alone. Dont disturb the shit in the bottom. Ive been down this road with model As. If you dont have the tank out and disturb that funk you'll chase it for years with replacing filters and clogged filters and blowing out lines. If the tank is detached from the cowl then fine, have it boiled out at a radiator shop. If its still attatched to the car leave it alone. One of my cars is a survivor 29 roadster. When I fill it with gas I look in the tank and its full of all kinds of rust and shit but it runs mint so I let it be

Do not over think this. If the tank is lined especially leave it alone. There's plenty of stuff to fiddle with on old cars. Do not fuck around with this. Leave it together. Drive the car.

 

Thanks for all the replies. Yes, this is a running, driving car. In fact the roadster won first in it's class at Detroit Autorama a few years ago, so this is a very well detailed and well done car. Because of the pandemic the car has been garaged and has sat for the past year, because there are no shows and no places to go to.

Quite frankly, I have never heard of denatured alcohol. I live in Ontario Canada and the reason I have never heard of denatured alcohol is because it is called something else here. With a little help from google I found that denatured alcohol is called methylated spirits here. I'll give the alcohol a try and see how it works out and hope it doesn't etch away some of the tank liner.

What seemed like a good idea at the time was the gas tank liner. Now in retrospect I should have just left the tank alone as I see in HRP's response, there was all kinds of trouble with gas tank liner failure. The liner in my tank has been alright so far, but you never know what is going to happen down the road. Again thanks for all the replies.

 

Add me to the list of people who have had trouble with gas tank sealers

I ended up cutting a 4" hole (with a hole saw) in my tank (not Model A) so I could get my arm in the tank and remove the failed sealer. Never again.

 

One more here that has bad luck with those gas tank liners. The one on my 48 Ford was so nasty and coming off in so many areas that I just bought a Tanks repop gas tank. I will never put that crap in another gas tank.

 

I know it's not everybody's experience, but a lot of failure with sealing a gas tank is in the application. It's not a one day process. The old guy that taught me was really good. He taught me to use ketone to clean the tank, along with nuts and bolts, which I've used gravel, and learned the chain trick here. Let it sit a day before agitating, and then go to town on it. Pour it out and repeat. Then once you're satisfied with how clean it is, rinse it out again and let it sit until you can't smell ketone in it anymore. Seal up the outlet, pour in the sealer, cover the fill hole and rotate every which way. Pour out the excess, and let it sit until you can't smell the sealer, then go one more day. I've never had one peel. You can also use fresh gas to clean out the sludge if you're afraid of disturbing the sealer, just might take a little longer

 

With the amount of baffles in a Model A tank, I think that is is nearly impossible to fully coat the insides of the tank with tank liner. You are bound to miss some area and that is where gasoline will get under and lift the whole mess. Motorcycle tank, no problem; They are small and have no baffles.

 

I'll never use the chain inside again. hung the gas tank on the jibb boom and stuck a chain inside. i rolled it round and round, flash light said it was cleaning up nice. Sooo... i get it on the work table only to find the chain was in a huge knot.......