Gas tank clean-out, remove old debris

My gastank has been painted and sitting empty for the winter and I have been trying to empty out old debris from the tank by removing the petcock and shaking it around. Alot of old particles (rust etc.) has come out, but when shaking the tank I can still hear some debris moving around in there.

I would like to rinse through the tank before using it again and was thinking about sloshing some fuel around the tank and draining it out the petcock hole (with the petcock removed). Anybody got any better idesas on what I should do?

Thanks.

White vinegar. It will remove rust too but should be ok for your paint. And any residual left after will burn with fuel. But you might be asked for fries for about a day as you might smell the vinegar when you run it. Also put gas in right after as the metal will be etched slightly and flash rust will appear quickly. Also use a magnet.

Proxy wrote: White vinegar. It will remove rust too but should be ok for your paint. And any residual left after will burn with fuel. But you might be asked for fries for about a day as you might smell the vinegar when you run it. Also put gas in right after as the metal will be etched slightly and flash rust will appear quickly. Also use a magnet.

I read some place about this method, that one should leave it in there for 48 hours etc. Will the vinegar mess up the gas tank sensor in any way?

Don't try to derust the tank with any sensors or the petcock in place. Best to fashion some plugs of some sort before that kind of work is performed.

My preference is Metal Prep (as sold by Home Depot) to derust. It's phosphoric acid, which will eat the rust in a few hours (keep rotating the tank every so often). Rinse well with water and follow with some alcohol to remove the water.

Definitely remove the hardware. I made block-off plates from sheet rubber & 1/8" oak. An old bicycle tube or something ought to work along w whatever stiff plates you can make. I also used a compression/freeze plug in the fuel filler opening.

You might want to put some bearing balls or nuts in the tank to bounce around & knock the rust loose. If the rust is real bad, you may need to use a tank liner.... you'll probably ruin the paint using one of the kits.

For cleaning the tank, others have had good results using either oxalic acid or The-Works. Oxalic acid wood bleach is available at the HomeDepot. The other stuff is probably sold at a bunch of places, such as Target or KMart. Phosphoric acid can be found in the tile section at home improvement stores. My tank only had light rust, so I used a 50/50 mix of muriatic acid & water.... I think The-Works is an HCl product, same as the muriatic acid.

When rinsing and flushing the fuel tank while it's removed from the bike, after sloshing the rinse solution (fresh gasoline, or mineral spirits, or common househole rubbing alcohol, or etc.) around by shaking the tank, I have better success with a fast dump out the open fuel cap, as opposed to slower drain from the petcock through the petcock hole.

Immediately thereafter, to avoid or minimize flash rust, may rinse with WD40 and/or fog with a petroleum base marine spray product designed for this particular purpose.

Besides soaking internally with the various rust removal solutions, such as acids of whatever type or special commercially available water-based rust removal products that are easier on paint, an alternative method for removing heavier rust scale inside the tank, is by putting a length of chain and/or sheet metal screws, etc, inside the tank, and then padding the tank with pillows, quilts, cushions, etc. to hold it firmly inside a clothes dryer, and then run the clothes dryer without heat for an hour or so, maybe longer if necessary, to tumble clean, break loose and polish the tank internally. Followed by the liquid rinse, fast dump and fogging.
This method allows the clothes dryer to do all the work for you, and help prevent developing Popeye arms.

Another method for rust removal is electrolysis, which works well for removing lighter rust deposits inside the tank.

Good Fortune!

I often wonder if this suggestion to put objects such as bolts and screws in a tank to clean it isn't just a prank. One I have fallen for myself. Yes the objects go in easy but getting them out is a bitch. I used quarter inch bolts. there was no shaking them out. I finally had to make a narrow hose for my shop vac and it was still difficult to remove them. Don't say I didn't warn you.

With regard to rust removers, I have used CLR, dish washing soap, and water with good effect. Just pour in about half a bottle of CLR, fill the tank with water, add the soap last. Close the lid give it a good shake with care not to drop. Let it soak between 24 and 72 hours and pour out. Rinse with more water and inspect. If you want to remove more rust repeat. If it looks good, spray in a good amount of WD-40 and slosh that around and drain it out. The WD stands for water displacement. Then poor it a quarter cup or so of motor oil and a a cup of gas and shake that a bit and drain it out. Your good to go.

jakedude wrote: I often wonder if this suggestion to put objects such as bolts and screws in a tank to clean it isn't just a prank. One I have fallen for myself. Yes the objects go in easy but getting them out is a bitch. I used quarter inch bolts. there was no shaking them out. I finally had to make a narrow hose for my shop vac and it was still difficult to remove them. Don't say I didn't warn you....

Use ferrous material, which is magnetic, and which may if necessary be removed with a telescoping magnet.

Good Fortune!

Patton wrote:

jakedude wrote: I often wonder if this suggestion to put objects such as bolts and screws in a tank to clean it isn't just a prank. One I have fallen for myself. Yes the objects go in easy but getting them out is a bitch. I used quarter inch bolts. there was no shaking them out. I finally had to make a narrow hose for my shop vac and it was still difficult to remove them. Don't say I didn't warn you....

Use ferrous material, which is magnetic, and which may if necessary be removed with a telescoping magnet.

Good Fortune!

When I got my tank there was (and still is) a very-light surface film of rust inside. I set up a couple saw horses outside and put a cup or-so of muriatic acid in after duct taping off the petcock holes, then taped over the cap holes. I then lightly sloshed it around, and let it sit for a few minutes, then dumped it out the filler hole.
The inside metal looked beautiful at that point...until it was rinsed out with water. Then the rust immediately came back, and has been there ever since.
I want to repeat the process again soon, but rather than water I'd like to dump something else in there to neutralize the acid, so it does NOT rust again. Will kerosine work in place of the water, followed by a quick rinse with gasoline, and dump out?

I have been down this path a few times and just cleaned up the inside of one my 650 tanks last night.

Go to the hardware store and buy 5 pounds of roofing nails. Should cost about five bucks. The weight and shape of the nails offers great abrasive pressure to scrape off the surface rust.

1. Remove the gas cap and petcock.

2. Tape a towel around the outside of the tank to protect it. Cut a hole in the towel the size of the gas filler opening on the top of the tank.

3. Slowly pour the nails inside and shake the hell out of the tank for about 5 minutes rotating it with quarter turns. Make sure you go around a few times. (Put some classic AC/DC on the stereo and shake to the riffs if you have no rhythm

4. Empty out the nails into a pail. They all come out very easy and should be pretty much covered in a light rust film and you might even have some larger flakes of rust.

5. Fill up the pail with water to rinse off the nails and drain the pail. Lay the nails out on some clean shop towels and let the roofing nails dry.

6. Repeat the same process 2 or 3 times and eventually the nails will be coming out without any rust on them and no rust flakes. By using clean nails each time you will gauge the progress of the rust removal.

7. Once you are confident the inside of the tank is clean run a magnet along the bottom seam as this is where any small metal particles will be.

9. Store the tank in a dry warm area and wrap in a towel until ready to use.

10. Install petcock, fuel cap and add about a 1/4 tank of fuel. Give it a good shaking and then dump out the fuel. Fill to the top with fuel and you should be good to go.

Cheers-Colin

Wow, lots of different techniques on how to derust. Some comments...

Muratic acid (HCl) is strong stuff. If you go this route make sure to heavily dilute the stuff and after derusting, neutralize with a basic solution of some sort (like baking soda). HCl is often used in toilet bowl cleaner, but you can buy the stuff for cheaper from the hardware store.

Using roofing nails and the like to shake around in the tank will remove the loose rust flakes, but not derust the metal. You need a chemical of some sort to do that.

Using ball bearings in the tank to knock loose rust is far less effective than using something with sharp edges like the roofing nails. Aquarium rocks are even more effective since they get into the nooks and crannies to scrub the metal better, but they are more difficult to remove.

Phosphoric acid is the main product of choice in the painting industry to derust and prep the metal. It washes off without need of neutralization and is relatively safe compared to something like muriatic acid.

Some of the popular tank sealing materials, like Caswell's epoxy for example, suggests you don't need to derust before sealing but I disagree. Always derust as completely as possible. Rust under the sealer does nobody any good.