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.

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account