Best product to remove rust from tanks?

Hey guys, working on my '74 xl350 project and need to get the rust out of the gas tank and get it sealed. Which product works best in your experience? There seems to be a lot of choices and some are fairly expensive, don't want to buy something that doesnt work.


Depends on how bad the rust is. Kreem works well on some tanks. But it's the lower end of things.

A crude way to get rid of tank rust is to use small gravel or star washers.Put them in the tank and shake it around until basically sands the rust off of the inside of the tank.Clean it out and you can use one of the forementioned products.If you do decide to leave it bare carry some fuel filters with you they will plug if the rust didn't get completely cleaned from the tank.

Ive had decent exsperience with RUSTOL tank rust remover

If you plan on painting the tank take it to a radiator shop and have them boil it and coat it, it's the same process they do for car gas tanks, but you'll need to repaint. The up side is it take all the paint off for you. :naughty: If you are not going to repaint. I use muratic (pool) acid and the Kreem kit depending on how bad the inside is. :bonk:

There are basically three different methods.

The first is physical. The goal is to knock the rust out of there. A wide variety of material will work. You put stuff in there and shake it around until most of the rust is gone. I have heard of using gravel, nuts, bolts, chain, and other things to get the rust out. Some use petroleum based liquids, but I just use soapy water. Shake until your arms feel like they are about to fall off, then keep going. Then clean and rinse out. It can be hard to get the abrasive of choice out of the tank. If the rust is not too bad you can be done at this step.

The second is chemical. This usually involves some kind of acid. The acid removes what rust is left. Some use less powerful but safer products. I go straight for the Muriatic acid. It works great but the downside is that it is dangerous. Sometimes it works on the paint too. If you don't know what you are doing you could hurt your self or do a lot of damage. I use a 12 gallon plastic tote and dilute the acid in it. I wear hard core rubberized gloves and eye protection. Even this strong acid can take hours. When you are done you must neutralize the acid. It takes about 8 pounds of baking soda to neutralize 1 gallon of acid. Did I mention that it is dangerous? Don't try this at home...

The third is covering it up. This is what the Kreem or POR-15 do. They are like a gluing or painting the inside of the tank. These products cover up the rust and seal it.

No matter what I do I always use a fuel filter between the cleaned tank and the carb. I go with a paper element type, but I guess the sintered metal or screen types will work too. There is always some residual crud.

Exactly what cleonard said...

My own preference is either chemical or physical. The covering-it-up options just never seem to hold up for the long haul, and then you just wind up with ANOTHER layer of stuff to get out of there.

Actually, my own 1st choice is usually physical. Don't really have a reason why. I've always had good luck with diesel fuel and small nails. Anything that this process doesn't remove, doesn't need to be worried about! That being said, I always run in-line fuel filters, too.

I read on another board one time of a technique of using a quantity of BB's put in the tank, then wrapping and taping the tank in multiple-multiple-multiple layers of towels and putting the whole works in the dryer on the no-heat, air-only setting and letting 'er spin for a few hours. The guy swore by this, saying the tank came perfectly clean, with no forearms ready to fall off!

Anyway, good luck, whatever your choice.


I recently aquired a pair of XT550's. One has only 800 miles on it and hadn't been ran in 20 years. The other had been stored outside for five years. Both bikes were set up with the rings rusted tightly to the cylinder walls. In both cases I had to cut the timing chain, pull the head off, and drive the piston down with a block of wood and a hammer to get the cylinder off. The ring of corrosion at the level of the piston crown was incredible... well over 1/16" thick. Everyone who looked at them said they were junk.

I searched the internet and found this biodegradeable stuff called Evaporust. The manufacturer claimed that you just dunk the rusted part in the stuff for a half hour and it comes out rust free, doing no damage to the good metal. It sounded too good to be true, but it was pretty cheap at the local Autozone so I bought a quart, bolted the head back on one of the cylinders, put the spark plug back in, tipped it upside down and filled it up. I checked it in half an hour... nothing. I thought "Well, this was a waste," but I decided to leave it overnight anyway.

I didn't check it again for maybe twenty hours but when I did I couldn't believe my eyes! The rust was almost completely gone. There was still a small ridge I could feel with my fingers so I took a plastic coffee spoon and scraped the sides of the cylinder with it. The rest of the rust came right off. Then I did the other one with the same results. The cylinders are obviously pitted to the eye but the walls are smooth as glass to the touch. One is pitted quite deeply and is probably unsalvageable, but I think I can have the other bored and use it.

Whether this stuff will work on a gas tank or not... I have no idea. It doesn't work anywhere near as fast as they claim, but it does work. The residual fuel or varnish that seems to coat the bottom of most old tanks might prevent it from working at all on a gas tank, but it is pretty cheap and it's got to be safer than muriatic acid.

I use Acetone (available from a paint supply store) and a handful of washers and BB's that you shoot in a BB gun. Shake vigorously for as long as possible, dump out and let dry. Repeat until clean, then rinse with soap and water, then Kreem it.

I was careful to empty the tank, removed the petcock, and let the fumes dry out.

Sparks + gas fumes + closed container = bomb

Petcock still on = trashed lines.

I put a chain inside and shook it around. Then I added a dog's choke chain and shook it around. The upside is I have two chains to get out. I don't have to count bolts or how much gravel went in. This removed a lot of the rust.

Later, I will probably run some muriatic acid in the tank.

I just restored several old very rusty 2-stroke tanks and here's my $.02

I do both the "agitation routine" with nails or small bolts followed by acid but I found the acid that comes with Kreem needs a little help. EITHER leave it in for more than 24 hours as suggested in the instructions OR buy some acid (someone said it was muriatic?) and do the acid routine twice. Also, as someone pointed out to me, after you have scoured the inside, you don't necessarily have to

coat the inside with the white stuff. It will be bare steel, just like it started out life as a new tank. BTW, I cant imagine doing a really good job without taking the tank off the bike...

After reading the posts and being an Ex-poolguy I had some muriatic acid laying around, tried it on a hodaka tank and it worked pretty well. you can get it at any pool supply store

A crude way to get rid of tank rust is to use small gravel or star washers.Put them in the tank and shake it around until basically sands the rust off of the inside of the tank.Clean it out and you can use one of the forementioned products.If you do decide to leave it bare carry some fuel filters with you they will plug if the rust didn't get completely cleaned from the tank.

I have heard of this using anything magnetic, and sharp-so you can use a magnet to remove the pcs. And you are correct about not getting it all out-so a filter or two need to be with you for a while.

theres a nice product out that a couple of guys on the xl forum have used. its totally safe (ie- you could pretty much drink the stuff) and its re-useable. SPENDY though- bout $100 for a gallon. but you can use it over and over and over, just filter the rust chunks out with a coffee filter. do a search on the xl page at

Good info here. I have just acquired (not a dirtbike) my wife's old '73 Honda CL450 (from her father's shed/barn)......the damn thing has a custom flame job gas tank so anything that will hurt the paint is a no go.

Anyway.....just a thought....anyone considered something like BBs and somehow fastening the tank up to one of those old style paint can shakers??

I recently restored a '73 Kawasaki Triple which had been sitting in a barn for 20 years. Needless to say, there was a giant pool of goo at the bottom of the tank which had chunks of rust flaking off on the inside. My solution was a 3 step process; ok, 7 steps if you count the rinsing and the drying. First I used engine degreaser to get rid of the goo, and rinsed the tank with water, Second I used muriatic acid to clean out the rust, rinsing the tank with water repeatedly until I was sure that the acid was neutralized, And finally after the tank had dried completely, I used a product called Red Kote to seal the tank and prevent future rust. It worked great! After the Red Kote had dried I was ready to use the tank again. The downside is of course that Muriatic acid can be dangerous if handled improperly, but I don't think this is as bad as the huge downside of using chain or nuts and bolts--denting your tank from the inside and causing the paint to chip off. I personally swear by the acid method; if the acid is strong, it is quick and effective, and best of all (if you do it right) the tank is ready to reattach and use in just two days time. No repainting necessary.

EVAPORUST!!!! Definitly works. I used on two xr75 tanks, bolts, and fork caps, and everything came out almost perfect. The tanks were spotless on the inside.

Warning about muriatic acid, it eats aluminum petocks!

My petcock was melted as I watched.

Good thing I had a new one on in hand.

Warning about muriatic acid, it eats aluminum petocks!

My petcock was melted as I watched.

Good thing I had a new one on in hand.

Good point! When I used acid on my tank I removed the petcock and the gas cap and sealed off both ends with plastic sheeting. If there is one thing that acid does well it is eat metal. So anything that you don't want dissolved should be protected. The acid will eat some good metal off of the inside of the tank too. And the stronger the acid the quicker it will do this; so pay attention to what you are doing and don't leave the acid in too long.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now