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Rust in the gas tank


Morgan Wright

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While syphoning the gas out for winter storage, I noticed a little rust going through the syphon. I have a really big in-line fuel filter under the car, so I wasn't worried, but I thought I'd try to get the rust out of the tank again (I thought i did a good job 5 years ago, but I guess not). For the last 2 gallons, I dropped the tank and sloshed it all around, turned it upside down and drained the gas into a pan. This is what I got:

 

Rust.jpg

 

 

I poured clean gas in and sloshed it around again, and got the same amount out. Did it a 3rd time and 4th time, mountains of rust came out each time, and it wasn't even getting less each time. I looked inside the tank and noticed there were 2 baffles preventing me from getting all the rust out using the slosh method. 

 

 

 

Tank.jpg

Edited by Morgan Wright (see edit history)
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After about 5 sloshing rinses, I put all the rust together into a red "pong" cup and this is what I got. Notice the rust dissolved the cup which means it has acetone in it unless there is something else that dissolves plastic. There is about quarter of a cup of rust and the tank was far from being cleaned out!

 

 

DSCN4569.JPG

 

The way I figure it, I'm guessing that when I cleaned out the tank with Dawn and water 5 years ago, the bottom of the tank was coated with varnish which trapped the rust at the bottom of the tank, and after 5 years of driving the car, the new gas dissolved the varnish and released these mountains of rust. But I can't get it out because of the baffles so I dropped a spy camera and some little spotlights into the tank to see what these baffles looked like.

 

 

TopHole.jpg

bottom hole.jpg

LeftSide.jpg

RightSide.jpg

Edited by Morgan Wright (see edit history)
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There are only 2 holes in each baffle, about 1  1/2  inches in diameter. No way in heck am I going to get that rust out by just sloshing, because of these baffles. So I bought 2 gallons of this stuff which I think is the same as Evaporust.

 

 

 

 

Blaster.jpg

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I had great results with Moyer Gas Tank Renu.  Being your tank is in good shape structurally, it may be a good option for you.

The tank gets cleaned, repaired and coated on the inside.  Worth looking into.

 

MOYER FUEL TANK RENU
2011Western Avenue
Greensburg, PA 15601
1-800-328-9550

mailto:moyer@westol.com
Joseph H Moyer

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This is a good method to rid the tank of the final gasoline before using the rust remover. The radiator heats to around 200 degrees F which is around 90 for all you in centigrade country.

 

Please don't light any cigarettes during the process. The Surgeon General has determined that smoking can blow your garage up and kill anybody within 50 feet.

 

radiator.JPG

Edited by Morgan Wright (see edit history)
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I sprung for a couple hundred dollars to have my tank blasted/cleaned and coated with an ethanol compatible coating.  Most of the do-it-yourself kits I believe eventually breakdown using ethanol gas, at least mine did.

Hopefully I never have to worry about it again.

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1 hour ago, Mark Kikta said:

I sprung for a couple hundred dollars to have my tank blasted/cleaned and coated with an ethanol compatible coating.  Most of the do-it-yourself kits I believe eventually breakdown using ethanol gas, at least mine did.

Hopefully I never have to worry about it again.

 

Not me! I've coated gas tanks before, the coating is good for a while but eventually breaks apart, and then you get pieces of coating in the fuel. And I think they must be adding acetone to the non-ethanol gas to cut the water, did you see the pong cup above? 

 

Yesterday I added a gallon and let it soak. Today I did the 24-hour slosh and dump. The water was black as coal and this is how much solid rust was still in there. So I tossed the solution and added the other gallon of Blaster. For another 24 hour soak.

20221102_110736.jpg

20221102_110845.jpg

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1 hour ago, Morgan Wright said:

And I think they must be adding acetone to the non-ethanol gas to cut the water, did you see the pong cup above? 

Polystyrene cups will likely dissolve in any kind of gasoline, regardless of additional acetone or not. Seems like it has been a common duo (gasoline and polystyrene) for making napalm. PET plastic, what soda bottles are made of, seem to handle gasoline without issue, in my experience. 

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It is best to open the tank and sandblast the rust out. Repair any perforations and weak spots. We have a local radiator shop that does the service.

 

One tank was an early 1950's Bentley that had multiple chambers inside. Without removing the top for access it never would have been cleaned properly.

 

I have not use sealer on any of my tanks. All the decades of my cars sitting idle with water in the bottom of the tank are over. That's the sitting idle part. I am expecting another three decades of having the cars in use.

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The bottom of the tank is shiny steel now from the first 24 hours.

 

The next 24 hours I let it sit 12 hours in 2 positions to get one side to be shiny steel, this morning I sloshed it all around and poured out the black solution, and only this much rust came out, much less than before.

 

Now for the 3rd 24 hours I poured a 3rd gallon of fresh Blaster in to do 12 hours each on the 2 positions of the other side.

20221103_122914.jpg

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I did an experiment. The instructions on the Blaster (which is just Home Depot's version of Evaporust) says not to dilute it. I figure that is just so they can sell more. To find out, I took 2 very rusty bolts and set up an experiment:

 

On the left is a shot glass, half full of Blaster, undiluted.

On the right is a pong cup with half a shot of Blaster, diluted with 2.5 shots of water (so 5 parts water, 1 part Blaster).

 

Insert equally rusty bolts for 2 hours.

P1060152.JPG

 

 

Results: The diluted one worked better than the full strength one!!!!!!!

 

P1060150.JPG

Edited by Morgan Wright (see edit history)
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Wow! that's quite a difference! Good to know, although I don't think it is quite that simple. This stuff, well Evaporust anyway, eventually dies. The chemical is spent. There is a finite amount of rust a gallon of it will remove before it stops working.

 

You would get more liquid that way, and that would be good for dunking stuff. However if you are treating something really rusty that will need to be hit more than once because it keeps using the solution up, I think you are just dragging out the time needed to get finished. My own experience backs that up.

 

I have had to add water to it when using it in open top containers due to evaporation. It gets thicker when it loses water and doesn't work as well. Your mileage may vary.

 

I'll have to try that now. I have been wondering about it. I have definitely noticed that when you get to the spot your left bolt is at, or a little further, Evaporust slows way down to get clear to the bottom of those pits. That's still better than phosphoric acid, which will skin over and never get there. Maybe your thinner solution soaks through the rust faster. That would be a good thing.

 

Edited by Bloo (see edit history)
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58 minutes ago, Bloo said:

Evaporust slows way down to get clear to the bottom of those pits

Maybe it has something to do with viscosity; or more specifically surface tension.  Perhaps the full-strength liquid 'bridges' the pits, whereas the diluted solution is better able to wick into the pits.  Just a guess...  :unsure:

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2 hours ago, Bloo said:

Wow! that's quite a difference! Good to know, although I don't think it is quite that simple. This stuff, well Evaporust anyway, eventually dies. The chemical is spent. There is a finite amount of rust a gallon of it will remove before it stops working.

 

 

That's why I used a half shot of Blaster (the "chemical") for each one in the experiment. The one on the right was diluted 5 to 1 but it still had the same half shot of stuff to start with. I'm a science dork I know about those things.

 

Here is a picture showing how it cleans the bottom and sides of the tank, but doesn't reach the baffle walls. So tomorrow I'm going to do another slosh and dump, and then add a fresh 4th gallon of the stuff and fill the tank to the top with water, and soak 24 hours. That will get everything.

20221103_171155.jpg

Edited by Morgan Wright (see edit history)
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1 hour ago, EmTee said:

Maybe it has something to do with viscosity; or more specifically surface tension.  Perhaps the full-strength liquid 'bridges' the pits, whereas the diluted solution is better able to wick into the pits.  Just a guess...  :unsure:

 

Maybe it's because the diluted one has more water to dissolve the stuff into. Say the chemical is some sort of chelating chemical, the full strength one can eat into the rust but has nowhere to put it so it just sits on the bolt, but the diluted side has just as much chemical, and lots of extra water to take it away from the bolt.

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5 to 1 is a 20% ratio and has always been a standard "turn down ratio" for me in equipment operation. In boilers and pumps control becomes unstable under 20% in most instances.

 

If I was selling a product that could be diluted or operated dependent on some reduction ratio I would probably warn against it. If the label said 5:1 some whiner would mix it 10:1 and tell me it was no good. And tell his friends, the online world, and his dog as well. Maybe his friend's dog too.

 

I can control a product but not the user.

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That picture I posted above is the filling of the tank this morning of the 4th gallon of Blaster, diluted with water all the way to the top of the tank, which means diluted 1 gallon to 17. That came after I sloshed out the 3rd filling, where very little rust came out of the tank, compare this to earlier pics. That means most of the rust is gone.

20221104_152202.jpg

Edited by Morgan Wright (see edit history)
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6 hours ago, Bloo said:

If you are getting rusty looking stuff like that out, I'm thinking you aren't even close to done. The only byproducts of the process are black. That brown rust in the bucket wouldn't last an afternoon in warm evaporust in a warm room.

 

 

 

It was cold, and early in the morning, and outdoors.

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Looks like you are good to go. Having the access to see all around inside is a real plus.

 

I would not coat it. Just keep it full.

 

I will steal a little of Al's credit. I vented quite a bit of $2.00 per pound refrigerant into the atmosphere during the 1980s, while they were still doing a lot of nuclear surface tests as well. It all contributes.

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On 11/7/2022 at 8:41 AM, 60FlatTop said:

Having the access to see all around inside is a real plus.

 

I never had access, the tank was never cut open. I just found out that the best way to take pics of the inside of a gas tank is with a smart phone. Just stick the camera lens in one hole on the tank, on a sunny day, and enough light comes in the other hole you can see easily. I tried my 2 regular cameras, both high-end, and even a spy cam that fits right into the tank, but the best of all was the telephone. Who knew?

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