Fuel Tank Cleaning: Please, dear god, Take Out Petcock

So this isn’t a question post as much as an “I’m a dumbsh**” post. I figure I’d post it so that other noobs could learn from it before they tried anything stupid.

I have a peugeot 103 with a vey rusty gas tank. In the past, I’ve used muriatic acid to clean the rust out of tanks, and its always worked great. So I filled up the tank with the stuff but I didn’t remove the petcock

Huge mistake.

The petcock started getting really warm and sizzling, spewing muriatic acid everywhere. So I panicked and turned the petcock on, hoping to drain the acid into a container. This just sped up the chemical reaction and made matters worse. By this time, the entire clutch/variator was coated in acid and the garage was filling up with the gas that the petcock was offgassing. I was coughing pretty bad.

I quickly pushed the moped outside and found a 5 gallon bucket to dump the acid into. Since the gas tank is built in to the frame (horribly dumb design if you ask me) I had to flip the entire moped over. After the muriatic acid was out, I ran and grabbed a hose to spray the moped down.

Now, I’m down a petcock, and no closer to a rust free tank then when I started. Also I tried kicking the moped over and the clutch is slipping too much to grab the engine even when the decomp is engaged, so I’m pretty sure I melted the clutch linings as well. Who knows what else is damaged on the moped.

On top of it all, I probably did serious damage to my lungs.

So moral of story: Take out the petcock and prep when using HCl with a rusty gas tank.

Re: Fuel Tank Cleaning: Please, dear god, Take Out Petcock

lol, glad you saved the bike....ur lucky, it reacted with the zinc in the potmetal...the gas it was letting off was hydrogen, you coulda had a boom on ur hands there...

Re: Fuel Tank Cleaning: Please, dear god, Take Out Petcock

Muriatic acid? Its good for removing oxidation from aluminum but I would use something else to remove rust from a moped tank.

Options:

- vinegar (safest one but also least effective and will rust again quickly)

- citric acid (the tank will rust almost immediately again when your done)

- phosphoric acid (leaves a phosphatic surface which will resist rusting)

- some commercial stuff (Evaporust etc. - take your pick)

I use Phosphoric acid to remove rust and IMO it works nicely. Nice thing about it is that it does indeed leave a phosphate coating on the tank sufrace so no problem if you leave it empty for while working on other details on your moped.

Only few days ago I treated my gas tank (petcock in place) with it and no problems what so ever. The 35% phosphoric acid solution didn't damage the petcock or even the paintwork.

Rubber gloves and safety glasses are a must though. Did get a very small splatter over my shirt and its now riddled with tiny holes ;-)(edited)

Re: Fuel Tank Cleaning: Please, dear god, Take Out Petcock

Dirty30 Dillon /

Yeah, sorry about your mishap, but you gotta read them warning labels and do your research. Muriatic is pretty harsh stuff.

Even salt and vinegar will ruin petcocks.

Re: Fuel Tank Cleaning: Please, dear god, Take Out Petcock

Captain Janeway /

anything you use to clean a tank will eat up the rubber gaskets, etc on your petcock.'

Glad you're OK.

Re: Fuel Tank Cleaning: Please, dear god, Take Out Petcock

So yes, better overall planning could have helped - no question, but nice job quickly finding a solution. Good crisis planning and fast reactions are a mark of intelligence imo.

Re: Fuel Tank Cleaning: Please, dear god, Take Out Petcock

Anthony Lea /

I can vouch for evaporust in that it does exactly what it should, eliminates rust while keeping the area safe and non toxic. Can’t really beat it.

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