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How To Tell If Your RC Motor Is Bad

When your RC motor goes bad, your RC car will certainly experience a breakdown but many times, you won’t even be sure if the motor is really the problem with the car or if it is something else.  If you want to know whether or not your RC motor is bad, check continuity across the motor leads where any problem with the windings would show up. 

If it won’t run when the iots are hooked up, check the battery voltage and also check the voltage at the ESC motor leads, both of which should be really close. If the voltage is different, it’s probably the ESC that is bad, but if the voltage is almost the same, it’s probably the motor that has an issue.

You can also take out your motor and check the shaft using a drill. Secure the part of the motor that is non-moving to prevent it from turning. To make sure it is all secure, spin it slowly first, so that the motor doesn’t go flying away. While the motor shaft is spinning at the highest speed, you can get from your drill then get your voltmeter out. Have it set it to AC volts and measure the voltage between all the leads. 

All of them should be roughly the same. 

If they are not about the same, then it’s likely an issue with one of your windings. It is open or shorting. If your motor gets warm while you’re doing this test, what it means is that the motor is defective.

But, what do you do if your RC motor goes bad?

Let’s talk about it. Keep in mind that the method we’re about to explain works particularly well for brushless motors.

Replace the motor

If you aren’t someone who is very handy or if you simply don’t want to spend a lot of time troubleshooting your RC motor then you can certainly skip all of these steps and simply buy a new motor. Brushless RC motors are actually not that expensive so for many people simply replacing the motor and see if that fixes the issue is a good option. 

Other people prefer to work with their hands to try and repair things so if that is you then feel free to keep reading.

To see exactly how to replace the motor in your RC car check out the video below. 

Remove the motor. 

You should start by taking out the motor from the RC car. The exact way that this should be done varies depending on the model of your RC car but normally it is relatively easy to do. 

Check for foreign objects

Once you have removed your motor from the RC car the next step is to see if something happened to get inside of it that could cause it to stop working or stop working correctly. If you have recently been driving your RC car through a lot of brush, dirt, mud, etc. then some of it may have gotten inside the motor. 

Small metal shards are especially susceptible to getting stuck inside a motor since there are magnets inside of it. 

Take it apart

Once you are sure that there is nothing in the motor causing issues then you will want to remove the stator from the rotor. This is sometimes done with small clips or a snap ring but either way be careful when you are removing it so it doesn’t get damaged. 

Once you have the clip on you ought to be able to pull apart the statue and rotor quite easily. In some motors it is a little more difficult but it shouldn’t require any special tools and you ought to be able to take it apart by hand. 

Once you have the stator and the rotor apart you can then thoroughly inspect everything to see if there was something inside that you didn’t see earlier or if there is anything out of place that could cause the motor not to work. If there is anything inside that shouldn’t be or if something is out of place then simply fix it. 

Magnet repair

Assuming you located a problem with one of the magnets coming loose or being damaged, you will obviously want to repair or replace it. Most of the time the magnets won’t be broken but will simply be moved to the wrong or have come loose. 

If there is nothing visibly wrong at this step then it’s probably best to go out and get a new motor. 

If you do have a loose magnet or one that has moved your next step is to put it back where it goes. These magnets are often held in place by a small dab of glue that can come loose with time, overheating, or get knocked loose by a foreign object that entered the motor. 

If you have a magnet that is loose or moved you should be able to glue it back into place relatively easy easily. You should use a good CA glue that is relatively thin to glue it back in place but be sure not to use too much that would cause it to get on the front of the magnet or on the surrounding ones. 

Next you will want to check all of the other magnets and make sure there aren’t any other ones that are slightly loose or where the glue looks a little suspect. If there are any others that are beginning to come loose now is the time to reglue them. 


Once you have given your magnets time to dry you are ready to put your motor back together and reinstall it back in your RC car. 

You will put everything back together in the same manner as you took it apart originally. You will want to be careful when putting the rotor and stator back together as the power from the magnets can pinch your fingers if you aren’t being careful enough. 

Once the rotor and stator are back together you will then want to put the clip back on it to keep the parts together and then put the motor back in your RC car and hook it back up. 

Once it is hooked back up its now time to test your fix. Start your RC car up! 

If it works then great you have saved yourself a decent amount of money. If not then you have to check other parts of your RC car or replace the motor with a new one to see if that fixes the problem. 

If a brand new motor doesn’t fix the issue then it is likely a wiring or ESC issue and you can return the new motor and keep your old one as it likely isn’t bad. If a new motor gets your RC to work immediately then you know something either went wrong with the repair or there are other issues with the motor that you missed. 


There is nothing quite as annoying in the RC world as having something happen for no reason but with motors sometimes they simply go bad. Whether you are able to fix your RC motor using the method above or if you choose to go the route of replacing the motor entirely you should get plenty of use out of either of them. 

Ultimately you have to decide if it is worth your time to take it apart and try to repair it or if you would rather just spend the money, get a new motor, and depend that time racing.