cleaning inside gas tank

well as it turns out I have an m38a1 gas tank. I would love to keep it. Problem is, there is a rust/dirt/corrosion problem going on inside said tank. Please tell me how to clean this thing. I've seen things from a POR product to putting a chain in it and shake it like crazy to using pennies. What will work. what wont?

 

I know what I've done.

I put two boxes of drywall screws, strong detergent (power washer detergent - very alkaline) and water inside. Plugged the holes and shook for a long time. A magnet removes the drywall screws easily. I then used Hirsch etching solution and tank slosh and coated the inside of the tank. Basically I removed as much of the loose material as I could and coated the rest.

Described on the link on this page http://www.hirschauto.com/prodinfo.asp?number=GTS

 

I have used the POR 15 kits on jeeps, motorcycles, and garden tractors. It works well.

 

do you remember about how much water/detergent? That product looks very promising!

 

I cleaned my tank a couple of years ago. My jeep had sat for 20 years prior. In additon to a little bit of rust, the biggest problem was the old liner "paint" was falling off the inside of the tank, Jeep was 68 cj5. Today's gasoline contain alcohol, and this makes the liner release. It looked like a bunch of old decayed leaves in the tank when removed the tank, pulled the sending unit and filled it with water. I used a kit from eastwood http://www.eastwood.com/gas-tank-sealer-kits.html, which cost $50+shipping, which has everything except for a gallon of muriatic acid, and the rubber gloves. It took a couple of days to do the complete system, and then I had to dispose of the spent chemicals. Muriatiic acid diluted with water killed the weeds by the curb, but I live on a stone road. If I lived where neighbors might be concerned about toxic chemicals, I may have had difficulty getting rid of the spent acid, metal et ch and rinse. In all I probably spent $100 by the time I got done. Make sure the tank is worth the investment.

I initally cleaned the tank and didn't seal it. I cldeaned and heat dried the tank and put it back in the jeep and filled the tank, only to find a large puddle of gas under the jeep about an hour later, which prompted me to drain the tank and purchase the sealer kit.

My original problem was that the liner was so deteriorated, that it would plug the pickup tube and I could only drive about a mile before the engine would quit because the fuel pump was starved for fuel.

 

the liner looks fine, but the rust/dirt mixture is pretty thick. reason I'd like to keep the tank is its different. and well, I already have it. I'm pretty cheap these days.

 

I have tried all of the above remedies ...............but have never had any luck...........you can't combat the rust that's already taken place , the tank will have pin holes in it once you re-fill it and use it for a while.

 

To bad you are in PA. I have a source here in Washington that can clean and seal the hole tank inside and out. Now I don't have to worry about my M38a1 tank ever rusting.

 

Not exactly. It would have been similar to the instructions with the tank sealer. Hirsch sells a detergent, but I had the Home Center power washer detergent. I'm sure the exact amounts are not critical.

Red Kote gets pretty good reviews too. http://www.dimecitycycles.com/vinta...-red-kote-fuel-tank-liner-sealer-1062110.html

Do some web research about the tank coatings. The Hirsch coating instruction sheet is pretty negative about MCU (moisture cured urethane) - that's POR-15. Supposedly the POR-15 tank kit is just a formulation of their paint, sold as a tank coating. Search the web and you'll find horror stories about that product. Plus they recommend etching your tank with hydrochloric acid, which IMO is a bad idea. You can buy better (IMO) MCU than POR-15 if you like that product http://www.epoxyproducts.com/aluthane.html

Coating the tank took a whole summer weekend. You need to dry the tank after cleaning, and that will take a while. If the weather is warm, it goes pretty quickly. I put my air hose in the tank and bled a little air through it, to dry it faster. Vacuum cleaner exhaust should work too.

 

You said you have an M38A1 tank. Do you have an M38A1Jeep? If you have a CJ5, then $160 will buy you a brand new tank. I tried repairing an old tank a few months ago. The more I cleaned, the more pin holes appeared. Even after I cleaned it well, new pin holes kept appearing from the inside. I bought a new tank.

If the tank isn't too far gone, then I recommend the Hirsch product.

If you don't have an M38A1 Jeep, and the tank is still salvageable, then you might be able to sell that tank for enough to buy a new CJ5 tank.

 

actually its a bastard jeep. 70 cj5 frame, 50-52 m38 tub, the a1 tank was in the m38 upon purchase. Just thought it would be cool to use what I got, rather than search for parts that would cost more to own.

 

We've got one of those too. A CJ2A body on a CJ3A frame and engine, CJ5 radiator and a homemade wooden box on the back in place of the rear half of the body. One of my favorites.

I'm all for using what you've got. As long as the tank is sound and you can use it safely, nothing wrong with cleaning it up and using it.

 

Sammy,

I'll chime in on this one as well.

I've tried multiple methods to clean my original tanks as well. Chain, screws, vinegar and acid. I couldn't get it clean enough to keep the Red Kote to adhere properly. I came to this conclusion. As much as I wanted to keep the original tank, save money, and feel accomplished in bringing that old tank back to life. It was quickly becoming a money pit and two months full of Sunday's to try to get it clean. I purchased a new tank.

In the end, you'll be thankful that you have that clean reliable tank. It's one less thing to worry about. I'm now replacing my fuel lines and fuel pump. Fun money is scarce but, I'm attacking my build one section at a time....

 

I understand this tank may not work in the end, but unless I try, I'll never know.

 

Truer words have never been spoken!

Keep us updated*

 

You can try strapping it on the front of a concrete mixer for a while, to tumble some gravel or hardware inside.

One benefit of an M38A1 tank is the larger capacity. Also, I soldered about a hundred pinholes in mine before coating it, and it worked. The key is absolute cleanliness on the prep - such as using muriatic acid.

 

Hot tank and Red Kote.

I did mine earlier this year and so far so good.

 

When I was rebuilding my jeep, I had to do a ton of grinding and welding on it. I used a boat type 5 gallon tank with a quick connect and two ratchet straps to secure it into the bed of the jeep. When I had to grind and weld on the body and frame of the jeep, I would first remove the tank and run the jeep out of gas, so I didn't have the worry of a gasoline expolsion. I waited until the jeep was completed to deal with the gas tank. I could go a good ways on the 5 gallon, more than my back could stand . The boat type are really inexpensive, I got mine at Kmart for about $15 at the end of the summer sale, regular price under $30.

 

Comment about muriatic acid - it is industrial grade hydrochloric acid (HCl).

I would be very reluctant to put HCl in my gas tank. These tanks are zinc-coated steel. HCL reacts vigorously with zinc to make zinc chloride (ZnCl) and hydrogen gas (H2). This process is the most common way to make H2 in the lab, because the reaction is so vigorous.

So, you put HCl in the tank, and if there was any plating left on the inside, it's gone.

HCl reacts more slowly with steel (iron). So once the plating is gone, the HCl will etch the steel.

IMO you don't need a powerful acid like HCL to etch the tank. I would instead use phosphoric acid (H3PO4) or oxalic acid (H2C2O4). If you use CLR as the RedKote site suggests, it contains all three of these acids. The Hirsch tank etch is most likely phosphoric only. Both phosphoric and oxalic react with rust - phosphoric converts rust to black oxide, and oxalic dissolves rust.

I have had good results using the Hirsch tank etch and sealant.