Motorcycle gas tanks can develop rust on the outside and inside if they are made with iron or iron alloys. Rust will not only destroy a paint job, but it can also devastate the gas tank, clog up filters, and ruin the quality of your bike.
If you need to remove rust from a motorcycle gas tank, you’ll need to prepare the tank, decide on a method, gather the supplies, clean the tank, rinse and dry the tank, and then take steps to prevent the rust from returning.
You do not need to buy a new gas tank whenever your current one starts showing signs of rust. Rather than spending hundreds of dollars on a brand new tank, with just a bit of time and resources, you can remove the rust from your tank yourself.
Prepare the Tank
Rust forms on iron when it reacts with oxygen and water. Rust flakes away from its attached surface, and exposes more iron underneath. The new iron undergoes the same process with oxygen and water and forms another layer of rust. The rusted iron flakes away and the process continues until there is no more iron to react with.
If you notice reddish-brown patches on the inside or outside of your tank, there is a good chance that rust is eating away at it. While getting a whole new tank is the easiest way to solve this problem, it is a costly option, and there is a chance that you will not be able to find the same tank.
Rust only occurs in iron and products made of iron alloys. Some gas tanks are made entirely out of plastic materials, so they cannot rust. Other tanks are constructed with rust-resistant metals such as chrome-plated metals or stainless steel. While these metals are rust-resistant, under the right conditions, they can rust. In this article, I will be referring to iron alloy fuel tanks that show superficial rust forming inside of them.
Before you begin, you must remove any and all gasoline. Carefully remove the tank from your motorcycle and drain the oil. You can pour this out into a gas canister or barrel. Now, you will need to inspect the tank to see if it can be salvaged. Use a small flashlight, mirror, or your phone’s camera to look inside the tank and see how bad the rust is.
If the rust has spread deep into the metal, or if there are cracks in the tank, it is better to just replace the tank with a new one. Attempting to clean a tank that is badly rusted will do more harm than good as the weakened tank may not be able to withstand the cleaners placed inside. If you are trying to restore an old tank or are unable to find a newer version of the tank then, unless the tank is too damaged, cleaning it is the better option.
Choose a Method (Abrasion/Chemical/Electrolysis)
If your tank can be saved, then you will need to decide on what method you wish to use to remove the rust. There are three common methods you can use to remove the rust: abrasion, chemical, and electrolysis.
Abrasion is a method that involves using solid materials and liquid cleaners to scrape the rust off of the inside of a gas tank. Some materials commonly used are regular gravels, nuts, and bolts. The abrasion method involves a bit of a workout since you will need to shake the tank for a while to get the rust out.
Chemical cleaners are a more pricey form of cleaning out the tank and will require caution if you are using a strong cleaner. These cleaners do the work on their own without much effort on your part. Just pour it into the tank and leave the solution to work on its own. While store-bought cleaners have a higher chance of removing more of the rust, if they are too acidic, they can damage the tank.
Electrolysis is a method that removes the most rust from a tank compared to the other two methods. This process requires you to use electricity and water to remove the rust. There is no need for any chemicals or additional items. However, this method is dangerous because you can electrocute yourself if you are not careful.
For this article, we will focus on the abrasion method to clean out your gas tank. This process will take a bit of work, but it is the safest one to use as it presents little risk to you or your tank.
Gather the Supplies
Before we begin scrubbing the tank, it has to be properly prepared.
To make sure that nothing pours out of it, you will need to get some caps, corks, or screws to block all the holes in your tank. This will ensure that nothing spills out of the tank during the shaking process. Make sure that every hole in your tank, big and small, is secure and sealed up.
You will need to find the right abrasion materials that can remove rust from your tank without damaging it. Use small nuts, bolts, or gravel that can clean out the rust without damaging the tank any further. A dog chain is the best option because you can remove it from inside the tank easier. Make sure that these metals are safe to use and will not be able to damage your tank from the inside.
To ensure that the abrasive material does its job, you will need to use a liquid cleaner to help the material remove the rust. Distilled water, soapy water, and vinegar are some of the common cleaning liquids because these are safe for the tank and for yourself. Apple cider vinegar is a good liquid cleaner to use too. Be sure to test your chosen abrasive material in the chosen cleaner to see if any reaction occurs between them. If so, choose a different material or cleaner.
While you may choose to use stronger chemicals for the job, this is not highly recommended. Some stronger chemicals can eat through your gas tank, destroying it. And the fumes from some chemical cleaners may be toxic to your health as well. If you decide to use one, make sure to wear protective gear. Test the chemical out on something that is metal and expendable.
Be sure to have a hose nearby in case some of the liquid ends up on you or another unintended item.
Clean the Tank
Now it is time to clean out your tank. It is a good idea to do this process outdoors to minimize collateral damage. Wear protective gear such as goggles and coveralls. To begin, pour the abrasive materials inside the tank. If you are using small nuts and bolts, count them, or whatever you are using so you know how many you should recover at the end. Use enough to fill one or two handfuls.
If you are using a dog chain, put the whole chain inside the tank. You will not need to count each separate link; the chain will come out as one.
Next, depending on the size of your tank, add a quart or two of liquid cleaner. This liquid should not fill up the entire tank, but it should be enough to get into the tight corners of the gas tank and remove the rust from there. As the abrasives bounce around the tank walls, the liquid cleaner will soften up the rust, making it easier to remove.
Now, shake the tank vigorously. If you have a small gas tank, pick it up and shake it as if you are doing a workout. If you have a larger tank, you will have to get a bit creative. You can wrap it up in a blanket and roll it around on the ground. Shake the can for a while and then check the inside of the tank. Eventually, you should start to see the rust come off the walls of the tank, revealing a shiny layer of metal underneath.
Put the cap back on the tank and shake it again as much as needed. Be sure to turn over the tank regularly so that the cleaner can get into the corners of the tank. If you start feeling tired, you can set the can down outside and take a break. The liquid will continue to clean the rust away while you are relaxing. If it is cold outside, do not leave the tank outside because the cold can cause the tank to rupture.
Depending on how badly the rust is inside your tank, you may need to keep shaking the tank for a while. Just keep shaking until the rust is completely gone. If you are using a cleaner stronger than vinegar, follow the instructions and do not keep it inside the tank longer than recommended. Once all the rust is gone, it is time to empty out the tank and dry it.
The video below shows an example how to clean out rust in a gas tank.
Rinse and Dry the Tank
Naturally, you do not want the rust to return after all the effort cleaning it. To prevent the rust from returning, make sure that you follow these steps carefully. You are going to need five gallons of hot water, a metal bucket that your cleaner cannot melt, a water hose, dish soap, and a heat gun or hair dryer.
First, pour five gallons of water into a large pot and heat it on a stove or on a hot plate. The water needs to be hotter than room temperature but not hot enough that it is boiling. Leave this on the stove or hot plate and grab your tank.
Take your bucket and set it near you. Remove all the plugs and covers on the tank (hang onto these) and drain the fuel tank into the bucket. If some of the bolts and nuts fall out, do not worry because you will no longer need them. After all the cleaning solution is out, empty the bolts, nuts, or gravels out of the tank. If you are having some difficulty removing the chains, you can use a magnet to help retrieve them.
Check to make sure your tank is completely empty. Once you have done this, it is time to rinse out the tank. Grab the hose and stick it inside the tank. You may want to put on some protective rain gear for this next part. Turn on the hose and start shaking the tank around. The water will clear out the cleaner, and shaking it will ensure that it gets into the crevices of the tank. You will get wet during this part of the process. You can always shower afterward if you need to.
Once you have cleared the cleaner out, turn off the hose and drain the water out of the tank. Now you’ll clean the tank one last time. Use the plugs and plates to recover the holes of the tank. Next, add in the dish soap, as this will help remove the residues of the cleaner. Take the pot of hot water and carefully pour it into the tank. Seal up the opening and shake the tank for a minute. Leave the tank alone for about five minutes to let the water and soap do their work.
After the five minutes are over, drain the tank and rinse out with a hose. Next, grab your heat gun or hair dryer. You’ll use these to dry out the tank. Rust sets in when iron reacts with oxygen and water, and the tank has all three components. Using the heat gun removes the water to prevent rust from coming back.
Be careful not to overheat the tank as too much heat can ruin your paint job. Move the heat gun over the openings and use your fingers to make sure that parts of the tank are not getting too warm. If it is cold outside, dry your tank off in an area where it is warm and dry. If you leave the wet tank outdoors and unprotected, you will see something appear that resembles rust, form in the wet areas of the tank.
Do not worry as this is not actual rust, but a different material called flash rust. Flash rusts are tiny particles of iron that have become lodged on the surface of another metal. This type of rust is flakier than regular rust, so it tends not to stick around for long. Once you fill up your tank with gas, the flash rust will join the oil and get caught in the filters. In the long run, it should not impact your tank very much.
Prevent the Rust from Returning (Use Tank Sealer)
Now that the rust is all cleared out, steps must be taken to prevent it from returning. For a gas tank, a sealer is the best way to do that. Sealers keep the flash rust from accumulating and keep your tank in good health. There are many sealing types, but they are lumped into two groups: store-bought and fuel-soluble.
Store-bought sealers are as the name implies sealers that are bought from the store. The POR-15 49216 Fuel Tank Sealer is such a product you can buy. This sealer stops rusts, corrosions, and fuel leaks. It resists all fuels, alcohols, and additives so it will not come off inside your tank. Follow the instructions on how to apply it, and you should not have any issues with your tank.
Fuel-soluble sealers are sealers that come from regular fuels and oils. If you plan on reinstalling the tank after cleaning, use kerosene as a sealer. Just swish it around, and the kerosene will prevent the flash rust from forming on the tank’s interior. If you plan to leave the tank on a shelf for some time, use motor oil or tacky two-stroke oil as a sealer.
There are three methods for cleaning out a gas tank, but the safest one is the Abrasion method. For this process, follow the steps listed below:
- First, you will need abrasion materials to remove the rust and a cleaner to clean out the inside.
- Next, clean out the tank. Put the abrasion materials and the cleaning liquid inside of the tank. Seal it up and give it a good shake until the rust is removed.
- Once the rust is gone, you’ll need to rinse and dry the tank. Empty out the materials, rinse the tank out with a hose, and add in five gallons of hot water and soap. Allow it to sit awhile and then drain the tank.
- Finally, apply a sealer to keep flash rust from returning. You can use a store-bought product or petroleum products such as kerosene.
Following these steps should produce a clean and rust-free tank.