fuel tank coloration

autokunst

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I finally peeked into the fuel tank. A mechanic friend had cleaned out whatever was in there originally - so this is the first time I am seeing the inside of the tank. It looks like most of it is in good shape - just some surface corrosion which I could clean and coat. But I can't figure out the coloration on the bottom. It is hard (does not scrape off when I poke it with a stick). My theory is that a small amount of gas dried up in there years ago and stained/coated it. But I'd love to hear if anyone else has seen this color. It seems black with specks of gold. Maybe I struck gold!!!

The current fuel is about 1.5" full. You can see the "clear" liquid line above the dark color below. I am running two filters and they appear clean, so this stuff doesn't seem to be flaking off.
20191018-fuel tank color 1.jpg
20191018-fuel tank color 2.jpg
 

rsporsche

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Stephen,

i would get the POR 15 gas tank cleaner kit - 2 clean coats, then by the time you use the 'etcher' to prep it for the sealer coating it will look perfect.
 

autokunst

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I am sure you are both right. In general, I have concerns over solutions that come in a bottle (unless it is bourbon ;)). But I'll take a close look at the POR 15 system.
Stephen,
i would get the POR 15 gas tank cleaner kit - 2 clean coats, then by the time you use the 'etcher' to prep it for the sealer coating it will look perfect.
 

dang

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My E3 tank has this but it was about an inch thick. I've been able to scrape some of it off with a sharpened steel bar but it's so hard I'm almost at the point of giving up. I may just use it as is with an extra fuel filter. It doesn't feel right but if I can't chip it off I wonder if it will ever come off while being used.
 

Marc-M

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I am sure you are both right. In general, I have concerns over solutions that come in a bottle (unless it is bourbon ;)). But I'll take a close look at the POR 15 system.
I have used tank sealer may times - i even use it in new tanks and its works great - the trick is to follow the directions.

The problem with most tanks is when they part full of fuel and left for some time, and sometimes get condensation forming - then rust forms on the walls - then that get caught up in the fuel, that in its self is not a big problem as the filter will catch it...
 

Peter Coomaraswamy

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I finally peeked into the fuel tank. A mechanic friend had cleaned out whatever was in there originally - so this is the first time I am seeing the inside of the tank. It looks like most of it is in good shape - just some surface corrosion which I could clean and coat. But I can't figure out the coloration on the bottom. It is hard (does not scrape off when I poke it with a stick). My theory is that a small amount of gas dried up in there years ago and stained/coated it. But I'd love to hear if anyone else has seen this color. It seems black with specks of gold. Maybe I struck gold!!!

The current fuel is about 1.5" full. You can see the "clear" liquid line above the dark color below. I am running two filters and they appear clean, so this stuff doesn't seem to be flaking off.
View attachment 78818View attachment 78819
It looks like outer-space and I can clearly see a black hole!
 

stphers

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I have cleaned out many fuel tanks using a mixture of hot water and muriatic acid , throw some old nuts and bolts in there with the solution. Tape off all the openings and then shake it like crazy in s many different positions as u can. Flush it out with more hot water. Once dried, then you can use the sealer kit
 

dang

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I have cleaned out many fuel tanks using a mixture of hot water and muriatic acid , throw some old nuts and bolts in there with the solution. Tape off all the openings and then shake it like crazy in s many different positions as u can. Flush it out with more hot water. Once dried, then you can use the sealer kit
This has worked for me in the past with typical build up, but my E3 tank is really bad for some reason. I'm on about my fifth try with different solutions every time and close to giving up. Hopefully Stephen will have better luck.
 

autokunst

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I've read about the water and muriatic solution, adding the acid to the water of course. 1:1 ratio is what I've read, and even 2:1 if it is really stubborn. Is this the ratio you've used?
 

mark99

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try vinegar, buy the high consintration stuff that is sold to kill weeds, not food type
 

Wes

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I used dilute caustic soda to clean my tank. An old time radiator repair man gave me the tip.
Let it sit for week then flushed it out. Should have seen all the crap that came out.
Just make sure you seal it as soon a it's dry or it will corrode. I used 500ml of two-stroke.
 

autokunst

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Based on the suggestions herein, and some reading and research (I.E. googling and reading various other forums), I am thinking of starting with the muriatic acid idea to get that layer of junk off the bottom, then immediately after rinsing/neutralizing that, doing the full POR-15 system (2 applications of the degreaser/cleaner, one application of prep, dry and seal).
 

tferrer

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I've reached this quite a lot and came to the conclusion that muriatic acid and some of the other chemicals mentioned aren't the easiest stuff to mess with. I found an old school radiator shop that would boil it out and cote the interior for a reasonable number. The only problem is they're not many of these old-school shops left. There are just two in the Bay Area.
 

nosmonkey

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Had this with my golf where the filler neck had corroded and introduced loads of rust into the tank. Good stop gap I found was a load of neodymium magnets stuck under a nice easy to access area of the tank. Rust accrues around the magnets which can then be reached from the sender unit hole.
 
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