How Thermostat Is a Fuel-Saving Device


It was designed as part of the engine cooling system to prevent it from overheating.  The thermostat location varies on the type of vehicle; however, most are usually found close to the radiator and the intake manifold.



The thermostat consists of wax, a rod, a cylinder, and a valve.  In many cars, the thermostat is 2 inches (5 cm) in diameter whose job is to hold the flow of coolant to the radiator until the engine has warmed up.

The standard temperature for an engine to operate is between 194℉ (90℃) and 221℉ (105℃), any temperature below or above this will affect the engine’s performance.

The thermostat is of high importance as it would help your vehicle not to consume too much fuel, Unfortunately, in some parts of Africa, like Nigeria, some roadside mechanics ignorantly refer it to as a device that causes overheating, so they advise their customers to remove it, so wrong!

The impact of the thermostat on reducing fuel consumption remains a mystery to many.  The thermostat which is found between the engine and the radiator blocks coolant flow to the radiator until the engine has warmed up, that is the thermostat enables the flow of coolant into the radiator only at the right time.


  • The thermostat regulates and controls the circulation of coolants in an engine.
  • It prevents the vehicle engine from overheating.
  •  It also keeps the engine from being too cool.
  • The thermostat helps the engine to get warm quickly after cranking.
  • It enables the engine to maintain its operating temperature between 194℉ (90℃) and 221℉ (105℃).
  • Amazing but true, it limits fuel consumption in our vehicles.
  • It controls the working temperature of an engine.
  • At the initial crank, the thermostat prevents the coolant from flowing to enable the engine to get to its working temperature quickly.
  • Also, it helps coolant absorb heat before entering the radiator.
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How it operates and improves fuel economy

Apart from its common functions of regulating the engine temperature, the thermostat would help improve fuel economy.

Surprise?  How?  Whenever you crank your engine, it’s usually at a very cold temperature, The main valve of the thermostat remains at a closed loop to prevent coolant from running through the engine so it can heat up to operating temperature as we see on our dashboard.

When the Electronic Control Module (ECM) or BRAINBOX senses that the temperature is heating up closer to the operating temperature, it signals the Engine Coolant Temperature (ECT) sensor to command the thermostat to be at the open loop to allow coolant from the radiator flow through the engine for cooling.

The ECT, during this process, will also command the injectors to reduce the amount of fuel sprayed into the combustion chamber. What happens with this, is you will have a limited amount of fuel being consumed, yet it won’t alter the performance and efficiency of your vehicle engine.

When the engine temperature drops close to the operating range limit,  the  ECM will control the ECT to order the thermostat to close its valve to stop the coolant from flowing through the radiator to the engine.

If the thermostat is absent in your vehicle, it implies that there will be a continuous supply of coolant from the radiator to the engine causing the operating temperature below its expected range.

The low temperature will be a cause for alarm to the ELECTRONIC CONTROL MODULE which will trigger the ENGINE COOLANT TEMPERATURE (ECT) sensor to command the injector to continuously spray the fuel into the combustion chamber to heat the engine, thus, causing more fuel to be burnt.

Disadvantages of not using a thermostat

As much as it has advantages when used, so likewise, there are disadvantages when not used. As earlier discussed, the popular saying is being spread by many roadside mechanics in Nigeria that the thermostat in cars causes engine overheating and the Nigeria weather is too harsh on car engines.

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It is believed that it has the condemnation of lots of car engines. If you Remove the thermostat there will the over cool of the engine which is bad.

The work of the thermostat will increase fuel consumption. This will cause premature engine wear while the excess fuel will wash the oil from the cylinder bores.


The overheating of Vehicles is one of the common disadvantages of not having a car thermostat which can cause severe consequences.  As earlier explained, when the engine temperature gets to its standard operating temperature, the thermostat releases coolant to the engine to control the heat.

If the thermostat is absent, it will allow a continuous flow of coolant into the engine, which ultimately causes the coolant to dry up and then the car to overheat.

Heater Defect

The absence is one of the car heaters does not work. The coolant will flow uncontrollably in the engine whether it is warm enough to need it or not.

If you turn the car’s heater on and the thermostat is absent,   cool air will come out from the HVAC. When you raise the heater temperature, it won’t reduce it. In other words, instead of remaining too hot at all times, the engine will have a problem with being too cold.

Temperature Imbalance

The absence of a thermostat will lead to unusual temperature changes when the engine is running or working.  Without any prediction, the engine temperature will change and the radiator coolant will not flow in a normal way.

Poor Engine Performance

The unavailability of a thermostat will affect your vehicle’s engine performance because the engine runs ideally at a  particular temperature between  194℉  (90℃)  to  221℉  (105℃).

While overheating the thermostat can reduce performance, low engine temperature can also detour your vehicle’s engine performance.


Most roadside mechanics claim that the presence of a thermostat is not necessary in vehicles because it causes overheating.  They claim the weather in Africa is different from those in Europe or America.

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This is so erroneous because the vehicle manufacturers have placed it on a test run in the hottest part of the world and they noticed the engine temperature remains the same in every part of the world provided the measures are put in place.

Therefore, the presence of a thermostat is very important to keep the engine running at its operating expected temperature most importantly limit the consumption of fuel.

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