Save That Old Tank: How to Clean Rust Out of a Gas Tank
Many restoration projects stop abruptly when it turns out a car or motorcycle’s gas tank is full of rust. You can’t always find a replacement, and even if you can, it’s not always financially feasible. Therefore, learning how to clean rust out of a gas tank becomes a necessary skill. Fortunately, there are ways to eliminate rust inside a gas tank and avoid the potential negative impacts corrosion can cause.
Negative Impacts of Rust in the Gas Tank
When it comes to service costs for your motorcycle, it’s hard to put a price on the cost of getting rid of rust. In most cases, vehicle owners would probably rather replace a fuel tank than try and scrub the rust out of it. But that’s not always possible, meaning you must get creative when it comes to a solution.
Apart from how rust in a gas tank can affect car and motorcycle values, it’s also a serious performance and safety risk. Negative impacts of rust in the gas tank include:
● Inconsistent fuel flow, which can affect acceleration as well as your vehicle’s idling state
● Plugged up fuel filters and lines, which could cause pressure buildup or worse
● Circulation of rust inside the engine, which cuts down on the amount of air mixing with the fuel
Also, ethanol gasoline increase the risk of rust in your gas tank because they’re more corrosive than other fuels. You can use fuel tank additives to prevent damage, but they won’t help correct existing problems. The best solution to rust in the gas tank is to use one of the below methods to clean it out, then use a sealant or begin using fuel additives to prevent future recurrences.
Anyone from used motorcycles riders to classic car owners to boat enthusiasts can wind up with rust in their fuel system, so the key is mitigating the damage as soon as possible. Most of these processes are DIY, meaning they only take an afternoon or weekend of your time to complete.
How to Clean Rust Out of a Gas Tank
When you start shopping for a motorcycle, you may look toward used bikes as an affordable way to get the make or model you want. Unfortunately, the older the bike is, the more likely it has corrosion and other issues. Even modern options such as a 3 wheel motorcycle can develop rust in their gas tanks, especially if they run on alternative fuels.
Fortunately, there are multiple ways to clean rust out of a gas tank, including abrasives, chemicals, and even electrolysis.
Abrasive materials are a common method for removing rust from gas tanks. Any rough material which can scrub away at the rust can potentially be effective at cleaning rust off. Common abrasives for this purpose include:
● Pea or aquarium gravel
● Loose nuts and bolts
● Plain gravel
Using an abrasive requires that you remove the gas tank and use a method to ensure all the gravel comes out of the tank afterward. Most recommendations include using a liquid—whether water or a combination of soap and water—to help swish the abrasive material around and dislodge the rust particles.
Chemicals can include everything from vinegar and baking soda, which create a chemical reaction which foams and helps loosen rust, to muriatic acid or isopropyl alcohol. Using a combination of abrasives and chemicals can also be an effective means of thoroughly removing rust; just make sure the materials you choose are compatible and won’t further damage your gas tank.
Also, make sure to dilute the material to avoid damage to your gas tank. Consider avoiding solutions containing muriatic acid if your gas tank contains (or could contain) soldering, however, because the acid can act so quickly it may eat away the material before it removes all the rust.
Electrolysis involves passing an electric current through an ionic substance to separate the materials. You need equipment such as a 12V battery, a piece of ferrous metal (such as iron), and sodium carbonate.
Performing electrolysis to remove rust is useful for smaller objects, but with some modifications, you can use the method to remove rust from a gas tank, too. It’s important to exercise caution when connecting and disconnecting the power source, and you will need to ensure the ferrous metal does not contact the edge of the gas tank.
Suspending the ferrous metal (anode) can pose the biggest challenge in the rust removal process. The science behind this method is solid, however, and the electrolysis method can remove much more rust than other options.
Chemical Resealing Treatments
Rust cleaning and resealing treatments are also available, though these may not be effective for more severe rust issues. Also, some manufacturers highlight incompatibility with alternative fuels such as ethanol.
Seeking out a chemical resealing treatment at your local automotive supply store can prove easy, if not a bit expensive. You may also need to perform the treatment more than once over time.
Safety Precautions When Working with Gas Tank Treatments
Many rust treatments for gas tanks involve harsh chemicals or abrasives. When working with any chemicals, plus fuel, you should avoid breathing in the products and protect your face while working. To stay safe when working with gas tank treatments, take the following steps:
● Wear eye protection and a face mask for your protection
● Work in an open area with plenty of ventilation to avoid concentrated fumes
● Don’t mix products except per the manufacturer directions; chemical reactions can occur
● Ensure heat and power sources are away from the area before removing the gas tank or using any flammable product
● Store fuel and gasoline properly while working on the gas tank and fuel system
● When working with chemicals like acids (anything stronger than vinegar), keep a hose nearby to dilute any spillage
● Make sure to plug up all the holes in the gas tank to avoid spillage of potentially dangerous chemicals
Before beginning whatever rust removal treatment you choose, you should park in a safe and well-ventilated area. Then drain all the gasoline from the tank, remove the fuel lines, then remove the gas tank from the motorcycle (or car).
Cleaning Methods for Rust Removal
Read on for step-by-step instructions on each of the four methods of rust removal for gas tanks.
Abrasive Rust Removal
Once your gas tank is empty of gasoline, you can add a few handfuls of gravel, nuts and bolts, or BBs to it, then add some liquid and shake. Soap and water is an old standby for many mechanics, but vinegar is also a low-risk option that won’t damage most other surfaces in your garage.
Before pouring liquid (or small gravel) into the tank, seal all the holes with various sized plugs and materials. Then, put your abrasives in first. Afterward, add the liquid and begin shaking the tank. Depending on the size, you may need to rig a mechanism for shaking the tank, or you may be able to shake it manually.
Be sure to turn the tank on all sides (including upside down) to ensure the abrasive materials reach every side, nook, and cranny. When you finish shaking the tank, empty the liquid out, then rinse with water.
Rinsing with water helps flush out the gravel or other abrasive you use but be sure to shake the tank around and make sure it’s truly empty before letting it dry and replacing it on your motorcycle.
Chemical Rust Removal
Although technically vinegar is a chemical, it’s not as heavy-duty as other chemical options for rust removal. You can also use phosphoric, hydrochloric, acetone, or muriatic acid as the chemical abrasive.
The safest method of chemical rust removal involves mixing vinegar and baking soda to fill (or nearly fill) the tank. Let the mixture sit until it bubbles up and begins to change color with the rust particles. Then rinse thoroughly to ensure it’s completely empty.
Another chemical option which is relatively low-risk in terms of the potential for it to eat away the interior of your gas tank is using diesel fuel to remove rust. An abrasive plus diesel fuel can prove an effective means of getting rid of rust.
Alternatively, you can use heavier-duty chemicals in a safe dilution to clean your rusty tank. In that case, follow the label instructions for diluting and handling the solution. Follow timing directions closely as well; leaving a chemical sit for too long can actually eat through the walls of your gas tank.
To use electrolysis for rust removal, you first need a solution of sodium carbonate (or soda ash). The chemical composition is Na2CO3, and the most common brand is Arm & Hammer, which is often available in grocery and other stores. Hardware stores also carry sodium carbonate, typically in the hot tub chemical aisle.
You only need a couple of tablespoons of sodium carbonate to create a solution inside the gas tank. Just place the ferrous metal (iron)—also called the anode—inside the gas tank (suspended within the tank), connect the positive power source, and leave the setup to sit for hours (or even days).
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