You may think your engine would overheat without a thermostat in place, but actually, the opposite is true. A car without a thermostat would never even warm to operating temperature, much less overheat. This will allow your engine to reach optimal operating temperature, improving gas mileage and performance.Click to see full answer. Similarly one may ask, what happens if you take the thermostat out of your car?Typically removing the thermostat will cause the engine to overheat at normal operating RPM. When the restriction is removed by removing the thermostat, at idle too much coolant will flow typically causing the engine to fail to reach it’s designed operating temperature. how do I know if the thermostat is bad in my car? If you see your temperature gauge going into the red within the first 15 minutes of driving, your thermostat may be bad. Generally, if your vehicle is overheating within 15 minutes or so of driving it, this may be a sign that the thermostat is stuck. Step 2: Check the radiator hoses. In respect to this, is a thermostat necessary in a car? It’s purpose is to keep the engine at the proper operating temperature. When the engine gets too hot, the thermostat opens up and lets the engine coolant flow through the radiator, where it cools off. TOM: But taking out the thermostat can actually do quite a bit of damage on a modern car.Can I run my outboard without a thermostat?Yes, you can temporarily run your outboard without the thermostat and not harm the engine. No, you can not remove the thermostat and continue running the engine for long periods of time without causing harm to the engine. Here is a brief breakdown on why the thermostat is so important.