Polaris Sportsman 500 Overheating Problem & Solution

An engine overheating is uncommon. It can happen to your Polaris Sportsman 500 for a variety of reasons.

So, why is your Polaris Sportsman 500 overheating?

The most common reason behind your Polaris Sportsman 500’s overheating is that the thermostat, the fan, or the temperature sensor is not working. Other than those, it could be a weak radiator, a malfunctioning water pump, or a restricted system. The spark plug heat range may also be incorrect.

Before you take your vehicle to the mechanic’s garage, you can diagnose the issues yourself. Here is a comprehensive troubleshooting guide to assist you.     

Polaris Sportsman 500 Overheating: Troubleshooting Guide

Before we go ahead and dive in-depth into the problems and their solutions, here is a quick overview of what to expect.

Thermostat not workingEngine will overheatReplace the thermostat
Fan not workingNo airflow will generateReplace the fan
The temperature sensor not workingCheck engine light will be onReplace the temperature sensor
A bad radiator capCoolant leakingReplace the radiator cap
Water pump malfunctionHigh pitched whirring noisesReplace the impeller
Restricted systemRadiator leaking coolantClean the radiator

Reason One: Thermostat Not Working

Polaris sportsman 500 thermostat replacement

The thermostat in your Polaris Sportsman 500 controls your vehicle’s coolant system based on the temperature readings. So, if your vehicle is overheating, the thermostat might not work correctly.

If you do not know where the thermostat is located, find the main coolant hose and follow it to find the thermostat housing.

There is a very simple way to test the thermostat on your Polaris Sportsman 500. That is, take out your thermostat and dump it into boiling water. The thermostat should react, or more specifically, open when you do that. If it does not, the thermostat is defective. 


If the thermostat has gone bad, there is no other way than to replace it. Your mechanic can do that for you, or if you would like to do that yourself, here are the steps to follow-

Tools Needed: Screwdriver, socket wrench

  • Remove the main coolant hose from the thermostat coupling by loosening the clamp with a screwdriver. 
  • The thermostat housing is held to the engine block by two bolts that need to be removed with a socket wrench.
  • Take note of where the thermostat is and take it out.
  • The old gasket needs to go. Make sure no pieces go into the opening when you scrape off anything stuck to the surface.
  • Replace the gasket.
  • Replace the old thermostat with the new one. Place it in the same position as the old thermostat. A bell-shaped valve opening on the thermostat should be positioned at the top.

Remember to catch any coolant that leaks during thermostat replacement in a clean drain pan or bucket.

If that’s not easy to follow, here is also a video for more efficiency-

Reason Two: Fan Not Working

How to fix a faulty polaris atv fan

One of the reasons for your Polaris Sportsman 500 overheating is that the fan is not working. If the fan is not spinning, that must mean the fan is faulty. 

Remove the fan wire and replace it with a 12-volt battery. If the fan is okay, it should turn on.


If the fan is not good, replace it. Here is how-

  • You can find the fan behind your vehicle’s radiator. 
  • Unplug all the electrical connections of the fan. Disconnect the sensor connection and the power connection. 
  • Remove and replace the old fan with the new one.

Reason Three: The Temperature Sensor Not Working

Polaris ATV Coolant Temperature Sensor Location

If the fan is up and running, you will have to test the temperature sensor next. The temperature sensor wire is connected to the fan through a plug. 

To test the temperature sensor, you will need a multimeter (our pick: AstroAI Multimeter 2000 Counts Digital Multimeter). Set the meter to ohms and audible, so it will beep if the sensor is good.

Connect the two cables of the multimeter with the two plugs coming out of the sensor. Then heat the sensor using a dryer or however you prefer.

When the sensor is heated up, the multimeter will give a reading with a beep sound. If there is no reading, that means the sensor is bad.


You’ll have to replace the temperature sensor if it goes bad. Here are the steps to follow.

  • Let the engine cool down and then disconnect the battery. 
  • Take off the plastic engine covers.
  • Find the sensor, which should be near the thermostat housing
  • Disconnect the sensor and install the new one.

Reason Four: A Bad Radiator Cap

A bad radiator cap could be why your Polaris Sportsman 500 is overheating. That’s when the heat has nowhere to spread, causing the vehicle to overheat.

Before reaching any conclusions, you will have to test your radiator cap. There are two ways to test a radiator cap: a temperature test or a pressure test.

To perform the temperature test, you must put the radiator cap into boiling water. When the temperature is high enough, the radiator cap will open, and when it cools, it will close.

You will need a pressure tester to test the radiator cap using pressure. Then you need to follow the steps below.

  • Connect the pressure tester adapter to the radiator cap.
  • After that, connect the adapter to the pressure tester.
  • Pump the pressure tester handle until it reaches the radiator cap’s specifications.

Over time, the radiator cap slowly loses pressure. But if that happens rapidly, then the cap is faulty.     


Replace the radiator cap with a new one. Before replacing the old one, clean the surface area with a dry cloth. Also, make sure the new cap’s condition is good. 

Reason Five: Water Pump Malfunction


When your water pump impeller is not spinning, that means the water pump is not correctly functioning. Impellers are rotating components with blades that convert mechanical power into pump power.

You must inspect the impeller to ensure that the problem is with your water pump. You need to take it out and look for physical damage. Also, you can hear a loud, high-pitched noise from your vehicle.

To take out the impeller, you must place a bowl or a tray underneath the water pump. That’s because opening the impeller will cause liquids to leak out of your vehicle.

When you have a tray underneath, you will need to

  • Locate the impeller; it’s right beside the water, with a hose coming out of it.
  • Disconnect the hose by unscrewing it. That’s when the pump will leak.
  • Then you will have to take out the cover of the impeller, and it will leak out some more.
  • When you take the cover off, you will find the impeller. There is a nut in the middle; take it out to detach the impeller from the system.

There you have it. Check the impeller for damages; if there are no signs of any damage, your impeller is good.


Replace the impeller with a new one if it is damaged. Check out the video of the whole process if it helps. 

Reason Six: Debris In the Radiator

As you drive your Polaris Sportsman through dusty and muddy roads, your radiator collects dirt and debris. Eventually, after some time, the radiator gets clogged by too much of it, which restricts your cooling system.

So, if your vehicle is frequently overheating, look into your radiator. It’s very simple, loosen the bolts and take out the front shield for direct access. You can see if it has accumulated enough dirt.


If you think your radiator is dirty, you must clean it. For this home-friendly radiator cleaning method, you will need a coil cleaner.

Here are the steps-

  • Spray the coil cleaner on the front of your radiator coil. 
  • Make sure you get it on all over the coil. 
  • Wait for 5 minutes, and then you will see foam with dirt coming out from the radiator coil. 
  • Vacuum the foam and repeat this process if needed.

When to See a Mechanic

Polaris Sportsman 500 Repairing

Aside from the reasons described here, there could also be some issues that are difficult to diagnose. If your overheating problem is not solved by implementing these solutions, you’d better visit your dealer.


Is the Polaris Sportsman 500 water cooled?

No, the Polaris Sportsman 500 is not water-cooled. Instead, it uses a coolant specially designed for Polaris and similar vehicles. 

What antifreeze is in a Polaris Sportsman 500?

Polaris Sportsman 500 uses “Polaris Antifreeze 60/40 Premix,” made for Polaris snowmobiles, Ranger, and ATV high-performance aluminum cooling systems.

Can you use regular coolant in a Polaris?

Yes, it is possible to use standard coolant in a Polaris. Any coolant can be used in your Polaris as long as it is safe in the aluminum cooling system. 


The Polaris Sportsman 500 overheating problem is a common one and can happen for many reasons. Some of them are simple and easy to diagnose; others, not so much. If possible, get your Polaris to an expert if the diagnosis confuses you. 


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