What Exactly Is The Crud Jamming Our Gas Tanks?

[ericr]

we have frequent posts about cleaning and then sealing the tank, both of which seem iffy for a lay person, but it is unclear to me what the debris causing the problem actually is. Oh I am sure it could be lots of things but if the tank is galvanized metal, is it dissolving or flaking continually?

[redmodelt]

This is what it is plated with;
https://en.wikipedia.org/wiki/Terne
Mostly it's years of rust flakes, dirt, water and old dried gas that has become varnish.

[SteveB31]

It is usually either rust or dried up gasoline.

[RandyinUtah]

Or it could be the gas tank sealers that were sold twenty to thirty ago that are now breaking down and turning in a black tar like goo. I have seen this before on other people's cars.
I will never use a gas tank sealer after what I have seen.

[chap52]

I tasted it once, it ain't peanut brittle... Chap

[McMimmcs]

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Originally Posted by SteveB31

It is usually either rust or dried up gasoline.

Good logic plus add the sealer to it.

[gridleak]

Its shellac based tank sealer that was used before ethanol gas. Ethanol is a shellac solvent. When the egas is vaporized in the carb the shellac is free to coat everything from the carb on.

[Gold Digger]

For fine rust particles I put a strong magnate with a loop on top of it that I can pull out of tank every so often with a coat hanger with a hook on the end of it. Some times it looks like a porcupine but in the last year it has almost no rust on it.

[Jack Shaft]

Without cutting that tank apart it almost impossible to clean it fully.I had pretty good luck with an industrial hot water pressure washer with chemical,but the tank was out of the car prior to paint..my experience with sealants? It has to be spotless prior to use most fail to get the tank clean prior to use.