View Full Version : Whats the best way to clean out a tarry gas tank?

02-11-2009, 11:22 PM
I've done a search, and didnt come up with a lot of info. I also saw references to using Draino, but a search on Draino didnt come up with anything.

The bottom of the inside of my tank is covered with a black tar-like substance, and it spells like terpentine. The local radiator shop says he doesnt do gas tanks. He referred me to a place in PGH (2 hours away), but they have a 2-week turnaround, and I cant wait that long. I need it done within a couple of days.

What would be the best way to get the inside of the tank clean? Will laquer thinner remove the gunk? How is draino used to clean the tank? Any suggestions would be appreciated because I'm up against a wall here as far as time is concerned. I'll only have access to the rack for a couple more days, then the car has to be taken to the body shop. I'd like to have it back together and running while I can still use the rack, and before it has to be moved.

02-11-2009, 11:29 PM
What model Studebaker is it? Try SASCO for a new one, or one that can be modified. If you are in that big of a hurry, that may be your best bet.

02-11-2009, 11:34 PM
quote:Originally posted by whacker

What model Studebaker is it? Try SASCO for a new one, or one that can be modified. If you are in that big of a hurry, that may be your best bet.

57 Golden Hawk. I dont think anyone makes new ones for it.

02-12-2009, 03:40 AM
It's spelled Drano, not Draino. That might have hampered your search. But the Drano they market today is mostly useless for cleaning fuel tanks. Get hold of a couple of cans of Gillet's or Red Devil lye. Lye is sodium hydroxide, NaOH, and it's VERY caustic. It can burn your skin, or blind you if it gets in your eyes. BE EXTREMELY CAREFUL!!!

Put on heavy rubber gloves, a rubber apron or rain gear, and wear goggles or a full face mask. Seriously! Then put some warm or mildly hot water in the tank to just above the level of the varnish, then dump in one or two cans of lye, and slosh it around a bit to distribute it. Lye normally releases heat when it dissolves; putting it into already-heated water may actually get things hot enough to boil and spit at you. That's why the safety gear. And that's why it works so well. The hot caustic solution breaks down the tarry gunk, and turns it into crude soap, which is water-soluble. Leave the hot lye solution in the tank until it cools down, this may take several hours. Then pour the solution out of the tank, and dispose of it safely. I'd suggest you collect the used solution in 5 gallon plastic pails, slap lids on them and label as "caustic soda + trace heavy metals" and wait for your town's hazardous waste roundup. Perhaps your town has a hazardous waste collection site? When I did my Weasel tank a few years ago, I poured the lye solution on a patch of weeds, which has long since grown back with great vigor, LOL. Rinse the tank out with several changes of warm water, then inspect it and see how you made out.

One such go-round cleaned the bottom of my Weasel to white metal, and it's been OK ever since. If the tank has weak rusty spots, you may find them. Needless to say, this whole procedure should be performed outdoors in an area where leaks and spillage won't create havoc.

Gord Richmond, within Weasel range of the Alberta Badlands

02-12-2009, 10:04 AM
Here's my notes collected over the year, but never tried!

QUESTION I just have a little question to toss out there, what would you use to clean out a good solid yet rusted gas tank. I have a tank that is solid except for some rough surface rust inside. I've heard that Draino works as a cleaner but what else?

I did one recently with my sandblaster. I removed the sender & drain plug,and made one extra hole w/ a 7/8" hole saw and blasted away until I had removed every bit of the rust inside. I then shook & blew it out very thoroughly and sloshed some POR 15 gas tank sealer in it, to prevent further oxidation inside since the original galvanized coating was no longer in place.
It was easy to mig weld an elec. box knock-out over the access hole. The gas tank renew process is great, but now costs about $400.00.


Muriatic (hydrochloric) acid ...from a swimming pool supply store.
If you coat the inside with a sealer, you only need to knock the rough rust loose and use a metal-prep before coating. A friend of mine poured a few pounds of rough gravel in his, and rigged a belt-driven setup that rotated the tank for an hour or so, then poured out the gravel (and rust), rinsed out the inside, and used metal-prep before coating the inside of the tank. You can use old loose bolts, screws, nails, and nuts, also, if you happen to have a lot of them around you've been saving for a future trip to the waste management yard.

Here's a couple of links with some info:

I use a chunk of old logging chain...


Take it to the local "metal Laundry" (dip strippers) and for about $35, and a few days, you'll get it back perfectly clean, inside and out.
Go to your local radiator shop and get a quart of Red-Kote sealer, follow the instructions and for about $60 you'll have a clean and sealed tank, no more worries about it.


Dwain G.
02-12-2009, 01:09 PM
Is this tar-like substance solidified? If it isn't loose or melting and doesn't discolor the gasoline, it may be some sort of tank sealer.

Dwain G.

02-12-2009, 02:49 PM
It might be a sealer, and if its coming loose you need a new one.


'63 Avanti, zinc plated drilled & slotted 03 Mustang Cobra 13" front disc/98 GT rear brakes, 03 Cobra 17" wheels, GM alt, 97 Z28 leather seats, soon: TKO 5-spd, Ported heads w/SST full flow valves, 'R3' 276 cam, Edelbrock AFB Carb, GM HEI distributor, 8.8mm plug wires

02-12-2009, 02:58 PM
quote:From Dwayne G

If it isn't loose or melting and doesn't discolor the gasoline, it may be some sort of tank sealer

My best guess is that it is the residual of linear long chain and aromatic hydrocarbons that have been crosslinked by exposure to oxygen from the gasoline in the tank.

You have in effect a low grade polymer.

Gord is dead on. The way to attack the problem is to digest the "crud" with a strong caustic. Be very careful to add the caustic "lye" very slowly to the water in the tank. You don't want to be on the receiving end of an eruption from that stuff.

Bob :)


02-12-2009, 05:36 PM
The bottom of the inside of my tank is covered with a black tar-like substance, and it spells like terpentine.

mmmmm, already day old varnish(what used to be petrol).....[}:)]

I used muriatic acid before to clean gas tanks. BE VERY CAREFUL with muriatic acid. It has around the same potency as hydrochloric acid. It also should be used in very small doses with alot of water. When I cleaned out the tank I used gloves, mask, long sleeved shirts, a coat, and old jeans. You don't want to have bare skin showing when you're sloshing the tank around. I would also set the tank down for a minute or two and let the fumes vacate from the fill hole(as well as let the working properties of the acid do it's stuff. I went 2-3 rounds with using the acid and then hosed the tank clean before setting it in the sun to dry. The tank is still in use some 4 years later on the truck today :)


02-12-2009, 07:59 PM
Just a couple more thoughts. If the tank is rusty then acid will remove the rust and do a fine job. If it's a crud from gasoline reside then the caustic (Lye) solution is the solution.

IN EITHER CASE!!! Add the corrosive material (acid or caustic) to the water SLOWLY. Use eye, vapor and skin protection also.

If my Industrial background is correct, Muratic Acid is Hydrochloric Acid (HCL) in a concentrated solution. Usually about 30% HCL in H2O.



Chucks Stude
02-12-2009, 08:40 PM
Isn't Muratic Acid 20% HCL? Have used it for several things, but that is what I remember from the bottle. If there is rust, or bare steel, won't the Muratic eat thru the tank? IMHO I would think the Drano would be a better remedy for the gas tank.

02-12-2009, 11:00 PM
Eastwood sells a tank cleaner/sealer kit that I've had good luck with. Since you are in Pa (where they are located) you should be able to get it pretty quick. Im in NJ and usually if I order before noon I have items from them the next day or in 2 days at most.

02-12-2009, 11:41 PM
Yep, muriatic acid IS hydrochloric acid. Just an old "commercial name" for the stuff.

Trust me, a strong base, like lye, (aka caustic soda, or more properly, sodium hydroxide) is the best treatment for a varnished fuel tank, because it actually breaks down those long-chain hydrocarbons that form the varnish. And lye won't eat the metal (much) unless it's aluminum, in which case all bets are off.

The acid would be good for etching the metal prior to treatment with a sealer.

Gord Richmond, within Weasel range of the Alberta Badlands

TX Rebel
02-12-2009, 11:48 PM
I have used lacquer thinner to soften & dissolve tar & varnish in fuel tanks, but strong caustic is effective also. I would avoid the HCl. For stubborn rust and hard varnish and old, peeling tank sealer left by the solvents, sandblasting is very effective but 2 or 3 extra 1" access holes will have to to cut with a hole saw. After removing all sand, patching rust holes & access holes, use urethane tank sealer. Sealer will adhere much better to a clean surface.

Barry'd in Studes

02-21-2009, 12:41 AM
Gas tanks cleaned with anything and left with bare white metal will only rust at an accelerated rate.
Cold coating processes are done at the mercy of the ambient conditions at the time th compound is poured into and sloshed around in the tank. AND if the tanks has nay rust left inside then the componud coats over the rust and the rust just keeps goin deeper and deper. Remeber rust never rests!(enve though it's been covered over with anything!!
Only true cure is: Totally remove all rust down to white metal. This requires media blasting via access holes drilled in strategic locations around the perimeter of the tank.
Coat with a baked on plastic coating.

Seaarch out your nearsest GAS Tank USA agency, pay them their going rate and you'll get back a tank guaranteed for life. It's cheaper in the long run.

Start at www.gastankrenu.com.