Rusty Tank Cleaning

Rob Hoehn /

So yesterday I got my wisdom teeth out and was confined to the couch for most of the day. It was nice out, and I was iching to get my moped running again. Everybody left me on the couch, passed out from the drugs. When they came back to check on me, I was out back with gloves, googles, and some muriatic acid, following the scooter theriapist's directions on cleaning out a rusty tank. Needless to say, the tank looks great and all the rust and junk is gone, so it works well. Everyone couldn't believe that I was up and doing stuff. I just told them you don't need teeth to ride a moped. Maybe it was the drugs....

Re: Rusty Tank Cleaning

Where can i find the "Scooter Therapist's" method of cleaning out a rusty gastank?


Re: Cleaning Gas Tank with Acid

Chris Robertson /

I've used this method before. Here's how it works.

1. If your tank is removable, remove it from the moped.

2. Remove the petcock. Cover the hole with some cellophane and hold it in place with a rubber band.

3. Make sure you have a running hose nearby to rinse off any spillage.

4. Make sure you have a can of WD-40 present.

5. Dump in a litre (quart) of muriatic acid into the empty gas tank. You can buy muriatic acid at any hardware store for a couple of bucks --it's usually in the plumbing or pool section. If you want, add water to the tank as well to dilute the acid (I don't bother).

6. Shake, shake, shake. Slosh the stuff around for anywhere from 5 minutes to 20 minutes depending on how bad the rust is.

7. Remove the cellophane and rubber band and drain the acid/rust from your tank.

8. Rinse out your tank several times with water --you have to work FAST because your tank will begin to rust immediately (within minutes).

9. Put a new (clean) piece of cellophane over the drain hole, and hold it in place with a rubber band. Put about a half-litre (pint) of two-stroke mix into the tank. Slosh it around to coat the inside of the tank.

11. Drain the two-stroke mix out.

12. Fog the inside of the tank with WD-40 to seal the metal from the air.

13. Inspect the inside of the tank --if it's still very rusty go back to step five.

14. Put the tank back on your ped.

15. Fill the tank with two-stroke mix immediately.

Remember to dilute any spilled acid with water immediately. Do not get any acid on your paint or onto anything aluminum (rinse immediately if you do). It's probably a good idea not to get any acid on yourself either.

I've had mixed results using this method. It cleans out the tank quite well, but I find that the rust just comes back again.

I have friends that recommend just taking your tank to a radiator shop and having them seal it with whatever magic concoction they have available. My friend's tank was guaranteed for life.

Hope this helps!


Re: Cleaning Gas Tank with Acid

Ron Brown /

Chris and Rob,

These instructions sound fine to me except I use duct tape because it is so much stickier and Phosphoric acid does not promote rust like Muriatic acid does.

Phosphoric acid is used to clean stainless steel food processing tanks like milking machines on farms and brewing tanks at breweries.

Apparently, something in the acid bonds with the steel to inhibit rust.


Re: Cleaning Gas Tank with Acid

Rob Hoehn /


Is Phosphoric acid dangerous at all to work with? That sounds better to use that 'cause you don't have to deal the rapid rusting issue that I dealt with. I also bought some of those thick rubber gloves you can buy at the hardware store for the muriatic acid. Oh, the directions I got were off the scooter therapists website at


Re: Cleaning Gas Tank with Acid

Ron Brown /


As far as I know, it is no worse than muriatic acid. Here at my local micro-brewery, they spray it all over the place and no one died......yet.

Just wear your old clothes, because they may become religious and keep a hose handy for flushing.


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