The Stovebolt Site Forums The Shop Area General Truck Talk Simple Advice to Anyone w/rusty gas tank

My 51 GMC gas tank was so rusty that I could drive it for five minutes and the motor would just quit running as if it was out of gas....because...it was out of gas in the fuel lines. The bottom of thetank would clog up completely from rust and dirt. How do you fix that?? A $$$ Kit with the cleaner/coating?? NAW! That's not necessary. Just take out your tank, put about.....oh...36 lug nuts, a few peices of dog chain, a little screw driver, a couple rocks from your drive way, your lucky marble, and a penny with the head up inside of the tank with a couple gallons of soapy water. Plug every hole in it and get your identical twin brother to help you hold up in the air and shake the heck out of it. Shake it like paint in a can, and then stand it up on either end again and again so all the stuff can scrape off the sides of the tank. Just keep rolling it, shaking it, flipping it, swining it, and fla-sha-rolling it around. Keep on goign till you feel sick. Then dump it out and look what comes out. Then the rinse it THROUGHLY. THEN dry it out, THEN whenn you reinstall it don't buy that coating stuff that will enventually wear out and plug your line, just keep your tanks full and they won't rust anyway!! I did this and I am a very happy campe...I mean Stovebolter. Just wanted to spread this joyous FREE way to get something important done to your trucks.

I used a simular method.. but I just put a gallon or two of gas in the tank, then a couple double handfuls of gravel, then shook the [censored] out of it.

Worked like a charm.. lots of crud came out of the tank, and i've run about 4 tankfuls of gas thru it without any problem.

dont you run the risk of having dirt residue, even after a washing, in the tank and it eventualy getting into the motor? if yall didnt have any problems, i may just try it.

Shake Shake Shake Da bolt-tank
Shake the fu-el line
Shake Shake Shake Da bolt-tank
Shake it all the time.

Cliff59

Here in Germany a common thing is to put 5 pounds of SPAX screws together with an rust solvent in the tank and attach it to a cement mixer for 2 hours .

Frank

sounds like something that would work!

The fellows that restore old tractors often lash a tank to a the side of a tractor wheel, jack up that side of the tractor and let it revolve for an hour or so with some of the aforementioned items in it.
Scours them to perfection then they use some of that liquid tank liner.

I used two gallons of Muratic acid & sloshed for 5 minutes. Poured in two gallons of soda water to kill the acid. Poured it out, rised, let dry & coated with RedKote tank coating. Super easy. Those who have problems with the coating coming off usually didn't prep per instructions. I've used Kreem on the '70 HD & RedKote on the '38 Coupe and have had no trouble with either. I prefer RedKote over Kreem. It seems to flow better when wet and makes a harder coating when dry.
If you don't coat your tank you WILL get rust in your tank eventually. As you drive the gas level drops & is replaced with moisture laden air which immediately starts to rust the bare metal. Refilling the tank does not remove that rust. The rust continues to build over time.
The acid costs about $2 a gallon. Some prefer Phosphoric acid which is more expensive but safer to use. The RedKote is expensive but worth it at about $25 per quart or $75 per gallon.
As the old Fram commercials used to say: "You can pay me now or pay me later".

Good question.

My theory is that if you put clean gas in the tank, shake it around, dump it out, and the gas is as clean as it was when it went in, you probably don't have any appricable amount of dirt or general crud in the tank.

If the gas comes out reddish brown, better flush it again.

Of course, before i'd put any nuts, bolts, screws, or rocks into my tank to use as an agitator, i'd wash them in gas or some other petroleum based solvent/cleaner.

it's highly recommended that the tank be coated inside if it's been rusted - otherwise the bare surface left inside will continue to corrode, and regardless of the 'bits' that might plug things up [or get stopped by a filter], eventually you'll be faced w/ pinhole leaks showing up, especially along any seams

as Tiny sez, the internal corrosion will occur most at the level that is at the surface of the gas level due to the temp differential of gas and air causing condensation there, and a properly applied coating will not cause later problems, but prevent them

once rusted, the tank is on it's way out if it's not coated - "just keep the tank full" would hafta be fill it to overflowing and never drive it, and gas does evaporate!!

Bill

How much Redcote for an adverage AD tank?

And where do you get this Redcote?
Google it and nothing came up.

you can get gas tanks cleaned and coated at many rad shops, and I think Eastwood has stuff called "sloshing compound", may even be available at NAPA - or look for the Gas Tank Renu folks

Bill

FYI

The major german classic car magacine had an big article on this issue.

Here are the facts:

1. They found out that rust problems are more common now in the old cars.

2. The reason ist: the gas was reformulated a view years ago.

They blend now alcohol into the gas wich is prone to cumulate water.

3. Not only that, they found agressive bacteria in tanks of oldtimer that are not often driven.

In modern daily drivers with plastic tanks this is not a problem.

4. They state that the only cure is a good tank coating and a special gas additive when you don`t drive the truck - let`s say - during the winter.

Frank

It's RedKote with a "K". I bought mine at the local Part Plus store. Any parts store should be able to get it.

I'm operating from memory here so take this with a little salt. I think one quart would treat "up to 20 gal" if I remember right. I bought a gallon because it makes getting everything covered so much easier and the left over can be put into a tightly sealed container for future use. Just be sure to use a container that leaves almost no air in the container when the left over RedKote is poured into it. I used a left over 5lb peanut butter jar & another 1qt jar to store the left over from my tank.

I've cleaned tanks, sealed them with stuff like POR-15 etc and find that a little cheap insurance is always good to have. Carry a spare fuel filter and a screwdriver for the unexpected, at 10pm, when the engine goes sput sput. I even put a shutoff valve coming out of my tank in case I have to EVER change it. Tiny, to add to your idea of saving left overs in a tight sealed contain without much air. A trick I learned years ago is to blow into the container which replaces oxygen with your carbon dioxide and quickly put the lid on it. I've done this for years and it works on everything from house paint to urethanes in preserving them.

POR15 makes a kit which supplies cleaner, etching rinse and sealant. Cost about $60- After cleaning with any of the described methods above, (I have mine boiled out at the local radiator shop) this will make the tank like new inside, encapsulating loose material and even seal pin holes.
The trouble with any tank, even when kept full is the very top is always exposed to atmosphere and will collect condensation. The tank I just finished for example, the top surface was full of tiny pin holes.

The PO left me w/ one so rusted that . . . .
I took a fine mesh-screen and soldered it to fit inside a brass pipe (that threads into the bottom of my tank) the screen was 2.0'' long, so the screen acts as a pre-filter. This way it would not allow any crud into the fuel line. Add a filter and that worked.
Not only that he (po) poured a tank sealer into the tank w/o completely cleaning /degreasing. The sealer didn't really coat and a sheet of coating blocked 60% of the gas spout filler tube inlet. Gas always flushed out when we tried to fill the tank. We didn't see that until I took the rubber hose and filler tube off.
We have now replaced the cab mount tank w/ an under bed one.

well i found something different in a tank i took out to clean the rust out of. turns out it was more varnish then actual rust. the way i found this out, was that rust is still magnetic, and varnish isnt. the varnish particals look and feel like rust also. and for good measures, drop a magnet on the bottom of the tank to catch any rust that you may get in the future.

Hi

My '48 GMC's tank had water in it for a couple of years before I got it.

I put the tank which is located under the bed on passenger side.

Did all the above, no replacement tanks available.

1st washed it out with clean gas, then added more gas with 3/4 inch crushed rock. rolled and shuck it for about and hour. Pour out the mess, wash with lacquer thinner, then used Muratic Acid to prepare the tank, flushed with soda and water serveral times, then plain water, then alcohol to dry it out. Then used about a quart of airplane tank sealer, it is FAA approved.

Been driving the truck for 6 years since I cleaned it, also added a new fuel line and fuel filter at tank end.

Good Luck
GMCPic

I do the rock and shake described above. But I do NOT use rocks. I dump part of my spare bolts bin in there. They are
greasy but not dirty. So no new dirt is added.

When I did my last one (which was from So Dakota) I found a
bunch of charcoal in the tank. An old timer told me they used that to absorb water instead of 'heet'. This is news to me!

GMCPic, replacement gas tanks should be available for the under-bed '47.2-'48 trucks. I think it's the same as the '47.2-'55.1 Panel/Suburban/CE tank.

Why not spring for a new tank or go to the bone yard and find something to replace the old one.life is simple.don't make things hard

What I know from working on old JD equipment: they use a brass in-line sieve, about 1-1/4" long that fits into a 3/8" line past the tank shut-off valve. I plan to put one in my '48 2t. Probably get one from Deere.

Another good idea is to add an in-line filter ahead of the carb somewhere. I realize it's not original, and the purists might frown on it, but it's an extra bit of insurance.