How To Remove Rust From A Motorcycle Gas Tank

Updated on March 6th, 2022 | By Mohit Chauhan

Have you ever experienced this? The other day everything was running smoothly, and your motorcycle was doing exactly what you wanted it to do, but recently your motorcycle started experiencing engine sputters and stalls every now and then when you start it up. While you don’t see any symptoms, it doesn’t get any better. Chances are your fuel tank is either rusting from the inside or the fuel has mixed with rust particles giving you a run for your money!

Those who believe that only vintage motorcycles that are sitting for a long time are affected by external factors are under wrong impression. It only takes few months of negligence for corrosion to start forming up under your exhaust manifold, chassis, and even inside your motorcycle fuel tank!

With the passage of time and the lack of proper maintenance, oxidation is inevitable. And, while it is certainly not a pleasant job considering the amount of time it usually takes, cleaning your fuel tank by yourself will surely save you a lot of money. But removing rust from some parts of metal surface, like your fuel tank, is not always easy. Certain spots are difficult to clean and not all methods or products available in the market are suitable. So, to remove rust from your motorcycle tank and prevent it from reappearing, check out our simple and effective tips with a handy step-by-step guide.

How rust forms in the tank

No single tank can be manufactured from a single piece of metal. They are usually made by welding together three separate pieces; these are the bottom part, the top, and the left and right sides of the tank. It is a common practice to roll-weld the upper and lower parts together. Although, this is an economical process, but unfortunately, also a potential cause of corrosion.

The most significant contributor towards the formation of rust in fuel tanks is the presence of ethanol within the fuel. Since, ethanol attracts moisture, oxidation is highly likely, especially when the motorcycle is stationary for a long time and not moved. In fact, modern fuels contain more ethanol than they used to.

Another cause of tank rust is rainwater that gets sucked in through the fuel cap. Since water is heavier than petrol, it always settles in the bottom of the tank which eventually causes the tank to corrode.

Furthermore, motorcycles that are stored during winters with a half-filled gas tank are more likely to get affected from corrosion than the ones that are completely filled to the brim.

Step by step guide to de-rust and seal your motorcycle tank

First, you will need the following items to start cleaning rust from the inside of your tank:

An empty vessel
A funnel with filter
Fistful of small steel nuts
Rust remover (for example Evapo-Rust remover)

Dismantle and drain the tank completely. Use a strainer to separate dirt from petrol which can be used later to rinse the tank.
In order to clean the tank using dedicated products that are readily available in the market, you first need to thoroughly pre-clean the tank by throwing a handful of small steel nuts along with the solvent. Once done, soak the tank for about 30 minutes before shaking it gently back and forth. The nuts here will scrape away all the loose rust while the solvent will penetrate to remove every bit of corrosion on the metal.

4. Depending on the amount of rust, you may need to repeat this entire process 2-3 times before a clean metal surface is visible from the outside.

5. Once done, drain the mixture completely and rinse the tank with the petrol you had stored in the vessel.

6. Blow dry if necessary.

7. At this point, apply a sealant on the inside of the tank, using products like Kreem or KBS, to seal the tank permanently from corrosion. Allow the product to harden thoroughly before using the tank again. Some agents take at least a week to do their job.

8. In case there is a visible hole in your fuel tank, you may need to undertake some additional measures. This process requires a complete painting from the inside using synthetic rubber-based sealing liquid. You may need at least 2-3 liters to uniformly coat the entire tank.

9. After pouring the liquid, move the tank in all directions for around 5 minutes so that all areas are thoroughly covered with sealant.

10. Any excess sealant must be drained out immediately. To avoid the formation of puddles, a vacuum suction unit can also be used. Subsequently, the neck and the surrounding areas of the entry point should be coated using a brush.

11. Blow dry using a hot air gun.

12. Once your tank is dry inspect using a torch light. If you have achieved desired results, install it on your motorcycle again and refill it completely with petrol up to the brim.

Cleaning the tank using citric acid

Removing rust from the tank using citric acid is a relatively simple process:

Dilute the citric acid in (preferably warm) water, and pour the mixture into the tank.
In 10 liters of warm water, you need to add approximately 300 grams of citric acid. For larger tanks, increase the quantity of water and acid in this ratio.
Leave the mixture in the tank for 8-10 hours. You can increase the duration depending on the level of corrosion.
It is important to neutralize the acid before draining to prevent the tank from rusting again due to acid corrosion. To do this, add some sodium hydroxide (around half teaspoon) and stir well before draining.
Rinse the tank several times to ensure all the residual mixture has been cleaned out.
Once done, blow dry your tank using hot air gun to eliminate any traces of moisture and reassemble the tank back in its original position.
It is recommended to refill your tank completely with fuel to prevent any further risk of corrosion.

Removing flash rust from the tank using vinegar

If you are dealing with flash rust or other minor corrosion, it is best to treat the tank with a mixture of vinegar and oil in a ratio of 1:1. In case you have some cooking oil at home, it is perfectly capable of doing this job. To treat, pour the mixture directly in your fuel tank and allow the mixture to soak for at least 45 minutes.

While the acetic acid in vinegar de-rusts the surface, the oil aids in loosening the contaminants and prevents new rust from forming.

For best results, it is advised to add handful of screws along with the mixture and shake the tank well in a pre-defined interval. This further removes any traces of flash rust that are left behind by the mixture of vinegar and oil.

Removing rust from the tank using gravel stones

De-rusting the fuel tank with gravel stones is one of the cheapest and easiest alternatives.

However, it is important that the gravel stones are small and sharp-edged. Depending on the size of the tank, add some gravel stones (we recommend a quantity of 100 grams per liter of tank volume).

To ensure that the rust particles bind, some additional fluid should be poured in. For this, you should resort to petrol, since water might again promote the formation of rust.

Close the tank tightly and shake it thoroughly until the desired result is achieved. Depending on the level of corrosion, this activity might consume an entire day. Once the desired result is achieved, the tank must of course be emptied and cleaned again using petrol.

De-rusting the tank with media blasting

Media-blasting is the most effective and thorough, but also the most expensive method of de-rusting a motorcycle fuel tank. Several options are available for media blasting, including sand blasting and walnut blasting.

In this process, a flexible tube is inserted into the tank that has a small nozzle at the end. Subsequently, with the help of compressed air, the blasting agent is blown into the tank. These highly accelerated blasting agents penetrate inside the rust and bring the bare metal back to the surface.

Sand blasting is the process where sand is blown into the tank, whereas, in walnut blasting, crushed walnut shells are used. In addition, there is glass bead blasting, where small glass beads are used in place of sand.

But one major drawback of these types of tank de-rusting techniques is that the tank must be emptied and cleaned again at the end of the blasting process. This is particularly difficult with motorcycle tanks because motorcycles have small, angled tanks.

A thorough cleaning is recommended by rinsing the tank with cleaning fluids. This is best done with diesel, petrol, alcohol or a special tank cleaner. Also, you should use compressed air to blow dry the tank before using it again.

One of the best ways of media blasting is using dry ice, because with this method it is not necessary to clean the tank afterwards. In this case, the dry ice melts after blasting and then exits the tank by itself. However, it is recommended to thoroughly rinse the tank again after de-rusting.

One can rent a media blasting equipment from hardware store or take the tank to the workshop and have it de-rusted there.

De-rust using Oxalic or Hydrochloric acid

Since medieval times, hydrochloric acid (HCl) has been known to be one of the most aggressive chemicals in the world. They are one of the most effective agents to remove rust or traces of oxidation from metal surface.

However, these should only be used on fuel tanks that can withstand such kind of abuse. Modern day motorcycle tanks are generally not moulded from a thick metal sheet and may get damaged in the process. So, proceed with caution.

An advantage of using Hydrochloric acid here is that rust is removed very quickly and very thoroughly. HCL is one of the most efficient rust removers that exists, similar to phosphoric acid. However, unlike phosphoric acid, 25% hydrochloric acid is readily available at any hardware store.

In order to clean your gas tank using HCL, we recommend pouring some diluted acid in the tank and leave it open for some time. Make sure you are doing this exercise in a well-ventilated open space, since the chemical reaction of hydrochloric acid with rust will emit harmful fumes.

For your safety, we do not recommend shaking the tank since this might create spillage or splash.

Once you notice that the hissing noise / fumes have reduced, drain the acid in a container and thoroughly rinse the tank with water.

Repeat the process if necessary.

Note: Do not leave the acid in your tank for more than 30 minutes at a stretch. Doing so might cause an irreparable damage to your motorcycle tank.

Alternatives of Hydrochloric acid for de-rusting

Hydrochloric acid is quite popular and effective agent for de-rusting; however, it is very aggressive and can make the material of the tank more vulnerable to corrosion (metal rusts faster if de-rusting is done manually using HCL).

Oxalic acid (click to buy), in contrast to the former, does not damage or attack the paint. It is one of the most widely used products in the automotive industry to chemically remove rust from tanks without damaging the surface of the tank. In fact, small concentration of oxalic acid does not pose a problem, even in an immersion bath. Based on our practical experience, a concentration of 10 percent is sufficient, i.e., one part of oxalic acid to nine parts of warm water, to remove rust from a moderately rusted metal tank in an hour.

Depending on the degree of rust, however, de-rusting may take a little longer in this case.

Note: All acids (including Oxalic and Hydrochloric acid) are harmful and dangerous, which is why it is important to keep them out of the reach of children and always wear protective gloves while handling the acid.

Removing rust from the motorcycle tank by electrolysis

Rusting is caused when the metal undergoes electrochemical processes. If this Redox (Oxidation reduction) reaction is reversed, it can also be used to remove rust from ferrous parts.

Fundamentally, all oxidized metal parts can be electrolytically de-rusted. However, it is important that the workpiece must not be completely rusted through. Otherwise, it will entirely disintegrate during electrolysis.

Things you will need

A DC power source (battery, charger, etc.)
Two cables
A piece of metal (to make anode)
Soda (Sodium carbonate)
A piece of plastic board / wooden board (to hang the piece of metal we are going to make anode)
Rinsing agent / vinegar / petrol

Steps to remove rust from tank electrolytically

Hook up one cable to the positive (red) and the other to the negative (black) terminal of the DC charger or battery.
Now take the board and drill a hole in it. Then hang the piece of metal (your anode) on the board.
Next, dissolve 100 grams of soda (sodium carbonate) in warm water and stir for around 30 seconds.
Now fill the tank to the brim with the mixture of soda and warm water you just prepared.
Place the tank on a non-conductive surface (wooden table, floor, etc.).
Immerse the piece of metal that is attached on the wooden or plastic board inside the tank. Make sure the piece of metal is not touching the tank and is hanging in the middle. This is going to be your anode.
Now connect the positive terminal (red cable) to this anode.
Likewise, connect the negative terminal (black cable) to any part of your motorcycle tank.
Once everything is in order, switch on the charger. It is recommended to use at least 12Volts.
Disconnect the connection and clean the anode (metal piece) every hour and replace it if necessary.
After 24 hours you can see considerable amount of rust deposit around your anode.
Repeat this process for another day if required.
Rinse and clean your tank completely using any kind of rinsing agents and lastly with petrol to get a shiny rust-free motorcycle tank!

Sealing the motorcycle tank

When it comes to sealing, we recommend using sealing kits like Evapo-Rust, Kreem, or KBS Fuel Tank Sealer Kit which you can get from your local retailer. Typically, 250 ml will do for a standard tank, but this can vary depending on the type of tank you have.

After pouring in the sealant, swing the tank around until the liquid covers all the areas. Drain the rest of the liquid and collect it in a container. Do not rush, as it takes about four hours before a solid film forms.

Wait for around 15 hours before you apply the next coat. Do not wait for more than 24 hours as the second layer needs to bind together with the first coat.

Lastly, you will have to let the sealer harden for one to two weeks before you can install and use the tank again.

Bottom Line

Hope you found our detailed guide on de-rusting the fuel tank insightful and helpful. Once you have treated your motorcycle tank from rust, it is highly recommended to inspect your motorcycle thoroughly for any traces of oxidation.

The best way to avoid corrosion is to wash your motorcycle regularly and lubricate all the metal parts including the chain for a prolonged life.

Also see: How to clean motorcycle chain

For more details and information, feel free to write us back. Happy cleaning 🙂