Why Does Your Airsoft Motor Get Hot? 10 Causes and Fixes

An airsoft motor will always get a little hot while functioning, and the nominal temperature spike should have no adverse effect on your gun’s performance. However, if your airsoft motor gets excessively hot, there is one or, in many cases, several underlying causes. 

Your airsoft motor may be hot due to an unbearable load of the spring, excessive friction of the mechanical parts, high resistance in the wires, low power supply, loose connections, improper shimming, incompatible gears, and poor-quality components.   

Does your airsoft motor get hot all the time or in specific situations? Have you made any changes to your airsoft gun that can cause the motor to get too hot? This guide discusses all the typical & several user-specific causes of an unusually hot airsoft motor and the respective fixes. 

1. Stressed Motor

A motor converts electricity into mechanical energy. Converting one form of energy into another generates heat, more so if there’s friction or resistance. Thus, all motors produce heat. However, an efficient system will not get too hot. 

A stressed airsoft motor will get excessively hot. The stress could be due to many factors. You may have a spring that’s too demanding for the motor. The motor will attempt to operate the spring and, in the process, draw more energy if it can’t pull it efficiently. 

A higher current flow from the battery through the wires to the motor will cause a temperature spike. Any component inside your airsoft gearbox that compels the motor to work harder than it can, or should, will lead to unusual heat generation. Review the efficiency of your airsoft gun.

Video: Why Does My Airsoft Gun Motor Get So Hot?

How To Fix

Use a motor capable of running your airsoft gearbox. For instance, if you have an M140 spring, a regular stock motor will be stressed. Thus, it will try to work harder and produce more heat in the process. You need a high-torque motor, ideally one with more turns per armature (TPA).

Older ferrite motors are generally unsuitable for airsoft guns with medium specifications. If you have a powerful airsoft gun featuring a heavy-duty gearbox, you should choose motors that have neodymium magnets

High-TPA motors with neodymium magnets create a better magnetic field. Hence, you get more free spins without drawing excess energy from the battery. In effect, your motor produces less heat to operate the same gearbox, including the heavy-duty spring you may have in the airsoft. 

2. Failing Motor

Motors fail, even the premium-quality models. The wires on the armature may wear off with time. The different mechanical parts inside a motor may fail. If a motor is failing, your airsoft may get abnormally hot regardless of the gearbox condition or other specific connected parts. 

You will notice performance issues, too. The trigger response, rate of fire, or feet per second get affected when a motor starts to fail. The excess heat is one common symptom that your motor is failing or incapable of operating your airsoft gun. 

How To Fix

Replace a failing motor. Upgrade to one that can support any progressive changes you will make in your airsoft gun. Airsoft motors are more expensive than springs, batteries, and MOSFETs. A high-quality motor empowers you to choose other components without worry. 

3. Flawed Shimming

Flawed shimming will lead to an overheated motor. All the components inside your airsoft gearbox should be accurately aligned, with their heights adjusted for maximum efficiency. You shouldn’t use worn-out gears, be it the pinion, bevel, spur, or sector. 

Shims are tiny washers or metal discs used to adjust the heights of specific gears. If you don’t use the right shims for the gear axles, you will have incorrect heights, which will cause significant misalignment. Flawed shimming stresses the motor and also damages the gears. 

Missing teeth in any gears or incorrect motor height can cause inefficiency. When one or more components are misaligned inside the gearbox, the parts won’t function efficiently or smoothly. Thus, your airsoft gun will have increased friction, and the motor will be stressed. 

You may also have worn-out bushings. The bushings host the various gears and facilitate smooth rotations by reducing resistance when you run the motor. You must inspect all these components inside the gearbox to detect the cause behind an overheated airsoft motor. 

How To Fix

Open the gearbox, check the overall state, inspect the bushings and shims, and verify if all the gears are in workable condition. Correct any misalignment you may find. Adjust the heights of all the gears and that of the motor. Review the entire shimming to ensure there is no flaw.

Here’s a stepwise video tutorial to help you achieve flawless shimming:

4. Incompatible Wires

Thinner wires have greater resistance than thicker ones. Airsoft wires should be upgraded if you make progressive changes, whether related to the motor, battery, spring, or gearbox parts. Your airsoft motor will get too hot if the connecting wires pose an unusually high resistance.

How To Fix

Replacing wires is a relatively easy solution. However, you should choose the right gauge. You may opt for 16 AWG wires or thicker, depending on what you can fit into your airsoft gun. A few contemporary airsoft guns may have sufficient space for you to fit in 14 AWG wires. 

A 20 AWG wire can transmit much less current than an 18 AWG wire. If you build a heavy-duty airsoft gun, you will require 16 AWG wires. The choice depends on the current flow or amps your airsoft motor needs to draw to operate everything. Refer to this wire size chart to decide.

5. High-Resistance Circuit

The gearbox aside, your airsoft gun has a simple circuit. However, some components can create unnecessary resistance. The wires are definitely one critical factor as their gauge size creates a direct resistance. The other connectors and bridges may be a problem, too.

Take the MOSFET and fuse, for example. A MOSFET connects and regulates the current flow from the battery to the motor. Thus, it poses some resistance. Likewise, a fuse is also basically a form of resistance, meant to blow, or a breaker should trip to prevent excess current flow. 

Any excess resistance in the electric circuit reducing the current flow below the amps the motor needs for efficient operation will lead to unusual heat generation. You must review each of these circuit components to detect the problem and choose an appropriate remedy. 

How To Fix

Many airsoft enthusiasts don’t use a fuse. You may or may not consider such an option, depending on your preference and safety assessment. If you use a fuse, choose a premium-quality one that will not pose any undue resistance and reduce the amps. 

Always use a high-quality MOSFET. Connectors influence the current flow and thus, affect the efficiency of an airsoft motor. Poor-quality connectors will not only facilitate overheating of the motor but also impair your airsoft’s performance, especially in the midrange & heavy-duty guns.  

6. Flawed Battery

Lipo batteries are the industry standard for airsoft guns. You may have a 7.4 V or 11.1 V lipo battery. The voltage is a crucial factor, but you need to focus on the milliamp-hour and the C rating. These two attributes determine if your airsoft motor can draw sufficient power. 

The milliamp-hour or mAh is a lipo battery’s capacity. A 7.4 V battery with 1,000 mAh capacity lets you draw 1 amp or 1,000 milliamps in an hour. The C rating is the maximum energy output of a lipo battery. You cannot draw more energy than what’s safe for a battery to discharge. 

Now, if the 7.4 V battery with 1,000 mAh capacity has a 20C rating, the maximum energy your airsoft motor can draw is 1,000 mA x 20 = 20,000 mA, or 20 amps. However, the maximum output or continuous discharge will plummet as the battery drains out. 

Hence, this battery will suffice if your airsoft gun motor needs up to 20 amps of continuous current flow. But it won’t be as steady nor last as long as a 5,000 mAh battery with the same 20C rating.  

Heavy-duty airsoft guns may require anywhere from 10 to 20 amps of peak power. You must have a lipo battery with the mAh capacity and C rating to deliver a maximum output of up to 20 amps. Also, the wires should be of appropriate AWG to efficiently facilitate that current flow. 

The capacity and maximum output aside, a lipo battery may have an internal short. All three factors, a short, low mAh capacity and inadequate continuous discharge or maximum output, can cause a motor to overheat. 

How To Fix

Do not recharge or use a lipo battery if you suspect a short. Choose a compatible & powerful battery for your airsoft motor for the required mAh and C rating. The voltage implies how many cells a lipo battery has. 7.4 V has 2 x 3.7 V cells. 11.1 V lipo batteries have 3 x 3.7 cells. 

7. Excessive Friction in the Gearbox

Look for anomalies inside the gearbox if you’re still wondering why your airsoft motor gets hot, and all the aforementioned causes and fixes didn’t help. An airsoft motor will have to bear a greater load if there’s excessive friction among the gears and thus get unusually hot. 

You may have problems with the connections, wires, and shims. Also, broken or loose parts, an inaccurate angle of engagement, worn-out armature, and excessively tightened gearbox shell can cause an airsoft motor to overheat. Look for signs of damage and broken or burnt parts. 

Customization could also be an issue. You may find foreign objects inside the gearbox shell. Anything that prevents all the gears from freely moving increases the friction, and the motor will work harder, get stressed, and turn hotter. 

How To Fix

Ensure flawless shimming, accurate motor height & angle, and appropriate alignment or positioning of the various gears, such as pinion, bevel, spur, sector, and tapping plate. 

An airsoft motor should spin without any glitches. Check the tapping plate, piston, and rails. Look for any obstruction or excessive tightness preventing the piston from moving freely. 

The cylinder and piston head must be optimally shimmed, not too tight. Check if all mechanical gears are lubricated. The compression system should not be dry. Inspect the bushings, too. Also, if you have bearings in your airsoft gun, check those, as they cause resistance if worn out. 

If you find an obstructed, rigid, or excessively tight component, shave off bits of that part to enable free movement of all the mechanical gears. Damaged parts should be replaced. 

8. Poor Quality Components

Inferior-quality gears fail faster, but before that, they will pose problems, such as overloading the motor. A low-quality gear may lose a tooth, or several, sooner than later. Those loose parts will cause trouble inside the gearbox, including stressing and overheating the motor. 

How To Fix

Inspect everything, and you will find the main problem. Other than losing a few teeth, airsoft gears will undergo wear and tear. Edges will deform, and you’ll find other signs of irreversible degradation. The only solution is to replace these parts, and many are reasonably priced. 

9. Incompatible Motor, Spring, Gearbox, and Battery

Like the batteries, wires, and gears, a motor has a capacity, too. All of your airsoft components must be compatible for desirable performance. You cannot use a weak motor with a high-end spring. Similarly, a low-end spring doesn’t need a high-torque neodymium motor. 

Generally, you’ll spot any significant incompatibility when you use the airsoft gun. In some cases, subtle performance issues may go unnoticed, and you may only detect an overheating motor. This excess heat may warm up the battery, gearbox, and other parts, too. 

How To Fix

Review the airsoft gun specifications. Check your customizations. Rollback an upgrade. Restore to an earlier configuration that worked well. Get a compatible part to complement any new changes. The specific solution depends on a particular problem you detect in your airsoft gun. 

10. Semi-Auto Mode Causing Energy Spike

Airsoft motors may get too hot in semi-auto mode. Full-auto modes require a steady current flow. Semi-auto often demands a burst of energy transfer from the battery to the motor. This spike may cause temporary overheating, especially if the current flow meets high resistance.

How To Fix

Switch from semi-auto to full-auto and check if you have an overheating issue. This problem isn’t universal. Besides, your airsoft gun’s specifications, the condition of the gears, the parts’ alignment, including heights, the wire gauge, and other variables are at play, too.

Video: Airsoft Troubleshooting: Semi-auto problems


Always begin your investigation with the busiest electrical and mechanical parts: the gears, bushings, shims, spring, motor armature, wires, fuse, battery, piston, rails, and trigger. 

A stressed or overworked motor isn’t necessarily failing. Eliminate other possibilities before you think of replacing an airsoft motor. Replacing many of the other parts is usually more affordable.