Thermostat Problems – Will Affect Your Engines Performance

Thermostat Problems - Will Affect Your Engines Performance
Thermostat Problems - Will Affect Your Engines Performance

Almost all thermostat problems, will have some effect on your engines performance.

The thermostats purpose is to keep the engine at its proper operating temperature.

The thermostat is just a simple valve. It opens and closes in relation to engine coolant temperature.

Understanding How The Thermostat Works, To Avoid Thermostat Problems

The thermostat starts off at a closed position, when you start the engine. Consequently, helping the engine reach its proper operating temperature. While the engine is running the coolant temperature slowly rises. As a result, making the thermostat begin to open. The opening allows warmer coolant in the engine to flow into the radiator. In turn, the water pump pushes lower-temperature coolant from the radiator into the engine.

Thermostat Illustration
Thermostat Illustration

When the lower-temperature coolant reaches the thermostat the warmer fluid begins to cool. As a result, closing the thermostat. During engine operation, the thermostat actually never fully closes or opens. But, gradually nears either state to control coolant flow. This allows the engine to operate, at a specific temperature controlled by the thermostat.

The Engine Must Be Allowed To Run In Closed Loop Mode

So, what is closed loop mode ? In a nutshell, closed loop mode is where the engine operates with a feedback loop. A sensor closes the loop.

In open loop mode, the engine doesn’t listen to nobody. It just runs off a set of instructions; based on where the throttle is at, where the revs are, and so on.

The sensor in question is a lambda, oxygen or air/fuel ratio mixture sensor.

In closed loop mode, the engine listens to this sensor to adjust fuel/air mixture. In open loop mode, it doesn’t and thinks the engine is still cold.

The Thermostat Has Two Important Functions:

  • To accelerate engine warm-up.
  • To regulate the engine’s operating temperature.
Thermostat Problems
Thermostat Problems

Advantages Of Having A Properly Working Thermostat Will:

  • Help fuel economy
  • Reduce engine wear
  • Diminishes emissions and blow-by
  • Improves cold weather drivability
  • Provides adequate heater output
  • Helps with overheating

Common Signs Of Thermostat Problems:

  • Higher Than Normal Engine Temperature
  • Lower Than Normal Engine Temperature
  • Fluctuating Engine Temperature (Changing Erratically)
  • Poor Engine Performance
  • Engine Takes A Long Time To Warm Up
  • Engine Overheating
  • Popping-Boiling Noises Coming From Your Heater

Most Thermostat Problems Happen In One Of Two Ways:

Stuck Open Thermostat

There is continuous flow of coolant into the radiator causing the engine to run cold. Also, overcooled engines run inefficiently. Which leads to increased fuel consumption and higher emission levels. As a result, engine parts enduring more wear. In addition, the car interior will not heat up properly.

Stuck Closed Thermostat

The circulation of the coolant is blocked. So, the coolant cannot get to the radiator to be cooled. As a result, causing the engine to overheat.

The consequences of an “open failure”; may be less catastrophic than those of a “closed failure”.

So, if your engine has overheated for any reason, replace your thermostat. Thermostats are cheap and can be purchased at your local auto parts store.


So, vehicle manufacturers are under intense pressure to; produce cars and trucks that produce fewer emissions. Closely regulating the cooling system is one way to do that. Finally, by achieving finer control of existing systems; and using different techniques to regulate temperatures.

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