Fuel tank clean up.

M

Mactriple

Hero member
Location
Wide Bay Queensland
I am trying to clean a tank which has had fuel sitting in it for over 5 years. The fuel has turned to a thick black "tar". I was told that conc HCl would clean it out. I can't bring myself to do that and used about 60% instead. That started to work but looks like needing litres of the stuff and I am worried about the tank surface inside. I have used nuts and bolts and the shake method but that won't work here. A car radiator place won't touch it. Any ideas out there would be appreciated! Cheers, Ian
 
I’ve used Oxalic acid crystals dissolved in water before to de rust a tank, you can try that, I’ve never used it on the tar like substance you mention though.
 
Years ago, I tried concentrated sulphuric Acid to derust a Triumph tank, really nasty stuff, never again. They use it at 10/1 in the building game to clean brickwork, it's called Killed Spirits. Car engine rebuild shops use some high-tech parts washers, getting that into and out of a tiny cap, but whether they want to do it is another question. Lots of derusting options, tar cleaning, no idea. Auto shops sell Tar remover for outside car panels, getting litres again, who knows.
 
What's in fuel that can turn to tar-like sludge??? Doesn't the fuel just evaporate (if it can vent) or sit and get that stinky stale fuel smell (if unvented)?
 
Splash out £15 on a tub of DEOX-C made by Bilt-Hammer. I've cleaned at least 4 or 5 tanks using this and it's worked every time.
A couple of tips, use the whole container, empty it into the tank first (it's powder) and then fill the tank up to the brim with boiling water from a kettle, you'll need to boil the kettle a few times! I always wrap the tank in one of those NASA blankets, the insulated silver foil used for loft insulation. Shame the tank as often as you can and leave it for 2-3 days shaking it when you can. The NASA blankets will keep the water hot for at least 12 hours or longer.
When you drain it out you'll be amazed at what citric acid can do.
Once I drain a tank out I dry it with a hot air gun and then tip a small amount of diesel in the tank and give it a swirl. It stops it flash rusting.
 
Thanks for the replies. I am not fighting rust only. I have handled that successfully before. What I have is from a lot of unleaded fuel sitting for a very long time. Just to get the tank cap open took days. I presume that the fuel vapour condensed on the cap and turned to sludge.
 

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Mactriple said:
Thanks for the replies. I am not fighting rust only. I have handled that successfully before. What I have is from a lot of unleaded fuel sitting for a very long time. Just to get the tank cap open took days. I presume that the fuel vapour condensed on the cap and turned to sludge.
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Is it all over the inside of the tank? If so it's possibly what's left of an old tank liner gone bad. Is it easy enough to scratch off with a flat steel blade? Or does it stick like shit to a blanket.
 
Over the years on this forum lots of posts about both rusted tanks and tank liners gone bad. Lots of remedies with different chemical cleaners and shaking with bolts and nuts etc.

Also as Vince said, may be best route if your not sure the chemical shake will work. Very frustrating getting filters and carbs continually plugged with a bit more residue that was missed.

Of course cutting the tank a lot easier to justify if your going to repaint it anyway.
 
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