How To Fix A Dent In A Motorcycle Gas Tank That Works Every Time


The gas tank to a motorcycle is usually the first thing people notice about the machine altogether. It’s a great way for a rider to express his or her personality and is one of the best ways to customize a motorcycle.

But it can be an eye sore if there are any dents in the tank, even if they’re just small ones. As annoying as they are, motorcycles are especially susceptible dents in the tank because of where they’re normally stored: the corner of the garage.

I have restored over a dozen motorcycles and repainted every single one of those gas tanks which included dent repair. I have used every method imaginable to get dents out. This article will describe the best way and exactly how to get them out so you’re not embarrassed to take your motorcycle for a ride.

Different Methods Of Removing A Dent

Every motorcycle I’ve owned had some sort of dent(s) in the tank when I bought them. That was mostly because I bought older bikes and it was only natural for a few dents to be in them especially since the paint was stock and no one had ever paid attention to the tank before.

It’s important to remember that no matter how you attempt to repair a dent in a tank, you will need to completely remove the tank from the motorcycle and empty the gas inside. Once you drain the gas, poor some rubbing alcohol inside the tank and keep the cap open to let the residual gas evaporate. Rubbing alcohol is soluble with gasoline so it will help with the evaporation process.

There are several methods out there that can help repair a dent that you’ve probably heard about. The first method is using some type of air bag to pop out the dent.

In theory, you get some sort of air bag such as an inner tube to a small tire or a blood pressure cuff and stuff it inside the tank behind where the dent is. As you slowly inflate the tube, the pressure should work against the dent and pop it back into it’s original position because of the memory of the metal.

A second theory is somehow getting a hammer or similar tool inside the tank and banging out the dent that way. This way can be a bit difficult because usually the only opening you can do this from is through the gas cap hole which isn’t very big.

The third theory to remove a dent in a motorcycle gas tank is by heating up that spot of the tank using a hair dryer or something similar and immediately spraying it with freeze spray. The idea is to have the extreme temperature change make the dent pop back into place.

I have also tried using dent repair kits. These include a mechanism that either drills a tiny hole in the metal or has an extremely good suction cup that connects to the center of the dent. These are supposed to be able to pull out the dents. These can be found at any auto store or online.

The last and final way I’ll discuss about how to repair a dent in a motorcycle gas tank is by simply using a body filler and repainting the tank. This is the way I suggest you use because it’s inexpensive and will ensure your tank is fully restored.

I have tried all of these methods mentioned above to remove dents. And to be honest, the only method that worked for me was simply using body filler and repainting the tank. The air bags I used always popped, the hammer method only caused more dents and was difficult to do, the heat/freeze method never worked, and the repair kits always caused some sort of other damage.

But that is just my experience. They may work for you if you’d like to try them. For me, I’ll always go with body filler and a new paint job and I can explain exactly how to do that.

How To Fix A Dent 100%

It may sound like a daunting task when you’re thinking about repairing a motorcycle gas tank by using a body filler and repainting it. But it’s actually a lot easier than you would think and it works 100% of the time if you take the right steps. In fact, you can make your tank look even better than it did before.

I repainted the filled the dents in the gas tank of my first motorcycle restoration. I had zero experience but just kind of went for it. And it turned out pretty incredible.

Here are the materials you’ll need:

  • Safety glasses
  • Respirator
  • Sandpaper, specifically 80, 150, 220, 300, and 400 grit
  • Sandpaper block
  • Old sheets and/or newspaper
  • Tow strap
  • Bondo or other body filler
  • Bondo Scraper
  • Green self-etching primer
  • 2-part catalyzed clear coat
  • Auto paint (the color of your choice)
  • Painter’s tape

Make sure you have an adequate amount of space to work in. Also be sure that pets or small children don’t have access to your work space to ensure there won’t be any further damage to your tank while you’re working. Use the old sheets and newspaper to cover up anything around you that you don’t paint dust to get on.

First, you’ll need to sand down the entire tank until it’s all smooth. You do not need to sand down to bare metal unless certain spots call for it to make it smooth. The only time I take the whole tank down to bare metal is when it’s peeling everywhere and has several thick layers of different paint. All that matters is that the whole tank is smooth after sanding.

Once the tank has been sanded and smoothed down, wipe it with a wet rag to get all the dust off. When it dries, you can use Bondo or whatever body filler you decide on and start filling in the dent using the scraper. Use a generous amount so you have a lot to work with when it dries. Important: it is not recommended you use body filler any thicker than 1/4 of an inch deep.

Wait for the body filler to dry according to the directions. Sanding it too early could mean sanding off big clumps at a time. Use the sanding block (not your hands) to sand down the body filler until it’s smooth. Start with the 80 grit sand paper and work your way up to using 400 grit. Apply more body filler if needed and repeat the process. You may notice some other small dents on your tank while you’re doing this, so this is a perfect time to fill those as well.

Once you get the filler sanded down and smoothed out, wipe it down with a wet rag to get off any excess dust. Tape off anything on the tank you don’t want paint on such as the gas cap. Now you’re ready to prime the tank. I like to use a tow strap and hang it from the ceiling somehow because that gives me full access to the entire tank. Click hereOpens in a new tab. to see the primer I suggest in my list of recommended upgrades.

Remember to do several coats and to not attempt to coat the entire tank with primer in one go. If needed, practice on a piece of cardboard or other disposable material.

Inspect the tank after the primer has dried. You’ll probably notice some parts that aren’t as smooth as you thought or that you didn’t quite get the body filler shaped how you wanted. This is completely normal and the main reason for doing that first coat of primer.

Sand down the areas that still needs attention and repeat the steps; use body filler, sand, wipe, and reprime. Continue these steps until it looks exactly how you want it when it’s primed.

After priming the entire tank and you have waited for it to dry, you’ll need to wet sand the entire tank using water and 400 grit sand paper. This ensures any rough particles are sanded off and make the tank extremely smooth which will give it an incredible shine when you’re done.

Now you’re ready for your new coat of body paint. Click hereOpens in a new tab. to see my other article that discusses the body paint I recommend for motorcycle gas tanks.

Take this step very slow. Again, practice using the body paint on something disposable. Paint the tank in several layers and don’t try to rush covering the whole tank in paint in one go. Make sure you have your respirator on any time you’re painting.

After you’ve painted about 3-4 coats, wait for the paint to dry according to the directions on the back of the paint can. Once that is dry, you’ll need to clear coat the entire tank. This ensures that gasoline or other chemicals don’t eat through the paint. Click hereOpens in a new tab. to see the clear coat I recommend in my list of suggested upgrades. Be sure to wear your respirator during this step because clear coat is especially potent.

Below are some examples of tanks I restored. Every single one of these had dents in them in which I was easily able to fix using this method.

What About Deep Dents?

As I had mentioned earlier, body filler should not be used thicker than 1/4 of an inch deep. Anything more than that can cause waves and ultimately chip off altogether. You should never use body filler on deep dents. So what do you do about those deep dents?

Depending on where the dent is, you can attempt to hammer it out from the inside and proceed with the steps described above. That way you won’t be filling in a huge dent with thick body filler.

However, some dents tend to be in awkward spots that are simply impossible to get to with a hammer or other tool to pound it out. If this is the case, you’ll simply need to get a new tank altogether or have a professional take care of it for you (though it’s likely less expensive to simply get a new tank).

The Cost To Fix Motorcycle Tank Dents

In my experience, fixing dents in a motorcycle gas tank is a lot less expensive doing it yourself than it is to take it in to a professional. Every motorcycle tank I have repaired myself has been done for less than $100 for all the equipment.

It will likely cost around $200+ dollars to have a body shop repair the dents for you. They may have some special tools that can help get the dents out without needing to repaint the tank, but those methods usually aren’t 100% and there will still be some scratches and warps.

The cost for a new motorcycle gas tank is usually around $150 -$200. You can get one for about $100 that is down to bare metal that you’ll need to paint yourself.

Repairing and painting a tank yourself has proven to work well, even with amateurs who are willing to learn a new skill. While some other methods may work, this is what I have seen to work the best.

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