[/IMG]I had to remove the gas tank to finish off the back of the cab with Dynamat. With a flashlight I took a peek inside and it appeared to look pretty clean. When I removed the gas sending unit I found out why it wasn't working very well. After the tank dried out and I went to move it some junk was coming out of the petcock hole. Well enough of that junk came out to warrant feather investigation and I'm glad I did. The bottom of the tank was showing signs of a lot of corossion. Threw some nuts in there and gave it a good shake, I couldn't believe all the crap that came out including what ever the heck that thing is next to the sending unit. So I ordered a tank cleaner and sealer product by KBS. The three step process instructions were simple and straight foreword. A friend and I were able to go through the whole process in about 6 hours. Should be good for another 60 years.

 

Kind of looks like the turn screw that holds the original air cleaner on to the carb?

 

Someone tossed it in the filler neck...for safe keeping????? ;-)

 

sorry...made me laugh...

 

LOL!

It's obvious your PO was a Filipino Witch Doctor! That excorcizes eveil spirits from your gas tank!

The three step process is very simply an phosphoric acid wash to neutralize rust. The you wash it out with soap and water. The next step is a wash of denatured alcohol to neutralize the water and prime the tank walls. The final step is that magic white cream you roll around inside - pigmented white shellac. $7 a quart at Home Depot.

 

Sardine can opener???

 

Julies, I know this is an older post, but are you cutting the the phosphoric acid? and how much do you use?

 

Before you go pouring acid in your tank give this a good read.

Gas Tank Sealer - Diesel Tank Sealer - Fiberglass Tank Sealer - Like Kreem

 

Depends on the strength of the phosphoric you buy. If you are buying from a chemical lab supply house you'll need to dilute it to ~ 10%. If you are buying it at the grocery store as "CLR" or other prediluted rust remover use it straight and expect a wait it's pretty dilute. If you buy it at a body shop supply or hardware store, check the directions on the container for diluting/use instructions. It won't harm good metal unless you let it sit for extended time or dry up inside the tank. For external surfaces you can find it in a jellied form sold as Naval Jelly.
If you can't sand blast clean, I like to use a "rust converter" product after the phosphoric acid treatment.

 

Julie
Alcohol is used to thin pigmented white shellac. The Alcohol in the gasoline may remove your protective coating. I suggest you coat a container with the shellac, let it dry and pour in some ethanol gas to see if it effects it before using it in the gas tank.

 

I used the POR 15 tank sealer and it worked great. They recomend a similar process as described by Julie with their Metal READY and MARINE CLEAN. I would highly recomend it.

 

Yes I understand that. But the theory is to wash with the "Denatured Alcohol" PRIOR to coating with the shellac. Denatured Alcohol, Isoprophil, and Ethanol are completely different chemical compounds.

First, the steps are

1) Acid wash to neutralize the rust (phosphoric acid is in essence Naval jelly without the jelly. It's also used to 'etch' metal as a prep for priming and painting)

2) Then wash out the acid and neutralize it with soap and water.

3) Rinse with Denatured alcohol. This serves two purposes, first alcohol will blend with water and make it burnable. The alcohol in this case absorbs the remaining soap and water becoming a diluted alcohol that will not hinder the coating process like water. Second thing is as stated, Denatured Alcohol is what shellac is "cut" with. The alcohol rinse acts as a primer (actually like a flux) for the shellac coat.

4) Coat with the shellac. (of course the folks selling these kits don't call it that. They'd rather sell you a pint of this 'miracle kream' for $35 than have you buy a quart of it at Home Depot for $10)

Once the shellac is dry, denatured alcohol will not re liquify it. And, there is a substantial difference between commercial denatured alcohol in a 75% solution and 10% Ethanol in gasoline (and I wouldn't fuel with anything over 10% EVER) Ethanol will not liquify dried shellac. As a matter of fact about the only thing that will take it off is ALOT of JASCO paint stripper!

Two post scripts: First AX pointed out something about the concentration of the acids. Best advice on diluting is "follow the instructions on this kit TO THE LETTER!"

Also, denatured alcohol and pigmented white shellac are two of the last great "make you pass out from fumes" chemicals around. IT'S GREAT! Be sure you do this
O U T S I D E !!!!!!! This stuff will knock you over!

Also, it is EXTREMELY VAPOROUS and EXPLOSIVE! Do not let anyone smoke within 75 feet (no kidding) do not let the fumes accumulate close to anything electric that may switch on with a spark (like the air compressor) and NEVER EVER allow it to come close to anything that dispenses oxygen - like your welder! It will blow you up!

Lastly, do not put any left overs or rags in a closed trash can. Lay them out and let them dry out in lots of fresh air. A good shellac should be completely dry and free of fumes in 45 minutes - even in very cold weather.