Planning to Run ATV Without a Thermostat? Here’s Why It’s a Bad Idea

This might come as a surprise to some of you, but ATV engines are fairly similar to the ones that you see on cars. This means that ATV engines are equipped with parts like a thermostat, camshaft, and even an alternator (which is called a stator on ATV). If for whatever reason, you might be wondering if running an ATV without a thermostat is a good idea, you have arrived at the right place to get your answer.

It’s not advisable to run an ATV without a thermostat. While the four-wheeler might be able to run without a thermostat, this can lead to serious engine damages that will cost a small fortune in repairs. If the ATV engine is not hooked to a thermostat, there is a chance that the coolant will circulate through the system too fast. This will not allow coolant located inside the radiator to cool dowm. That’s not all. Running an ATV without a thermostat will make it challenging for the engine to reach the proper operating temperature, which leads to cylinder damage.

Learning how ATV engines work is great. You will have the required know-how in order to get yourself out of sticky situations and don’t be required to pay a mechanic for help.

Can You Run ATV Without a Thermostat?

While you can ride an ATV without a thermostat, it’s not a good idea to do it for a long time. The thermostat is an essential part and it plays an important part in helping ATV engines reach optimal operating temperature. Moreover, the thermostat is also responsible for giving the coolant from the radiator enough time to cool.

The first thing that can happen if you choose to ride an ATV without a thermostat is that the coolant will circulate through the system faster than usual. The problem with this is that the coolant located in the radiator will not have enough time to cool off. Therefore, this will lead to overheating issues which can cause serious damage to the engine.

If an ATV runs without a thermostat, the engine will have a difficult time reaching the optimal operating temperature. While this might not be a problem if it happens only once for 30 minutes, it can cause excessive cylinder wear. The head caused by the fuel ignition will come into contact with a cylinder/head/piston that is much cooler than usual.

Why Does an ATV Need a Thermostat?

Just like with regular cars, the thermostat is an important part of an ATV’s engine and it shouldn’t be removed. The role of a thermostat for an ATV is to allow water into the jackets at the correct operating temperature. Therefore, the thermostat is responsible for regulating the water temperature, for helping the coolant flow, and for making it possible for the engine to reach the correct operating temperature.

How Do I Stop My ATV From Overheating?

If you notice that the engine is overheating, the first thing you need to do is pull over and turn off the engine. You should turn your key in the ignition because this will turn on the radiator and give it time to cool off the engine. Depending on how hot the engine is, you might need to wait on the side of the road for 5 to 15 minutes. When you determine that the engine is no longer overheating, you can turn it back on. Doing this will allow the coolant to start circulating in the system and create an optimal operating temperature.

I wrote a full beginner guide that explains what to do when an ATV engine starts overheating and how you can avoid serious damages. You can check out the guide here and learn how to stop ATV from overheating, and what are the reasons why this happens in the first place.

How to Replace a Thermostat on an ATV

It’s highly unlikely that you will have to replace a thermostat on an ATV far too often, but knowing how to do this will save you some money in the long run. Replacing a thermostat on an ATV sounds more complicated than it already is. Follow the guide below:

  • Before starting, give the engine enough time to cool down completely;
  • Locate the main coolant hose and use it to find the thermostat housing (located on the engine block);
  • Put a bucket under the thermostat housing to avoid spilling coolant that might leak out;
  • Now, start loosening the clamp that attaches the main coolant hose to the thermostat (you can do this with a screwdriver);
  • Once the clamp is loose, you can remove the hose (be careful of spilled coolant);
  • Take a picture of the thermostat before removing it so that you know how to place it back;
  • Use a socket wrench to remove the two bolts holding the thermostat housing fixed on the engine block;
  • Remove the old gasket from the opening and make sure to scrape off all the debris that is stuck on the surface;
  • Install the new gasket over the opening;
  • Now, go ahead and insert the new thermostat into the opening (use the photo as reference to place it in the same position as the old thermostat)

Sidenote: Some thermostats come with a bell-like valve opening and the opening needs to be placed at the top;

  • The next step is to replace the thermostat housing, cooling hose, and bolts;
  • Pour the spilled coolant back into the radiator and start the engine;
  • If there is no leaking coolant, you are good to go.

Final Words

Even though an ATV can run without a thermostat, I think that the risks of doing this are too high to be worth it. If the thermostat gets damaged and you need to ride the ATV home, this will not be a problem. However, you need to make sure to replace or fix the thermostat before going on another ride.

Bob Kelly

Hey there, my name is Bob and I've been riding ATVs, dirt bikes, and UTVs for most of my life. Going on outdoor adventures has always been my passion. I love sharing tips and tricks with beginners who are getting ready to join the world of outdoor enthusiasts. You can reach me at if you want to get in touch.

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