Engine Thermostat Problems – Will Affect Your Car’s Performance

Engine Thermostat Problems - Will Affect Your Car's Performance
Engine Thermostat Problems - Will Affect Your Car's Performance

Almost all engine thermostat problems, will have some effect, on your car’s performance.

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

So, the engine thermostat, is just a simple valve. It opens and closes, in relation to your engine’s coolant temperature.

Understanding How The Thermostat Works, Can Help Avoid Engine Thermostat Problems.

So, the engine 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. This 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.

Engine Thermostat Problems - Will Affect Your Engine's Performance
Engine Thermostat Problems – Will Affect Your Engine’s Performance

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.

Above All, 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.

As a result, being stuck in either position, will cause, engine thermostat problems.

The Engine Thermostat Has, Two Important Functions:

  1. To accelerate, engine warm-up.
  2. To regulate, the engine’s operating temperature.
Engine Thermostat Problems
Basic Engine Thermostat

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, Engine Thermostat Problems Include:

  • 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 Engine Thermostat Problems Happen, In One Of Two Ways:

1-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.

2-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 and have engine thermostat problems.

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. Engine thermostats are cheap and can be purchased, at your local auto parts store.

Overheating And Overcooling


So, overheating is the most common symptom, of a failing thermostat. Due to corrosion or aging, your car’s thermostat can get stuck in a closed position. If this happens, the thermostat will not let the coolant reach the radiator. And, as mentioned above, the engine will overheat, causing severe damage.


One of the lesser-known issues is the polar opposite of overheating. Overcooling happens when the engine does not reach the right temperature, to function normally. In this scenario, the thermostat is stuck open and overflows the radiator with coolant, drastically reducing the engine life cycle.

To prevent this, you should always watch your dashboard temperature gauge. If you don’t have one, monitor various warning lights in the instrument cluster. If you find yourself in a sticky road situation, try turning the heater on full blast to dissipate excess heat.


So, vehicle manufacturers are under intense pressure, to produce cars and trucks, that produce fewer emissions. Consequently, closely regulating the cooling system, is one way to do that.

Thank You !