How To Test The Thermostat (1992-1997 2.2L Beretta, Cavalier, Corsica, Sunfire)

Engine Thermostat Basics

You're probably already aware that the colder the engine is, the more fuel it needs to stay running.

With the engine consuming more fuel, gas mileage suffers and the engine pollutes more.

As the engine warms up and reaches its normal operating temperature, it needs less fuel to run and of course pollutes less.

The thermostat is one of the cooling system components that help regulate the engine's temperature so it can perform optimally and produce less emissions.

Here are some more details:

1. When you start your vehicle's engine:
   • The thermostat is closed.
   • The radiator fan is OFF.
2. As the engine coolant circulates in the engine only, its temperature increases, and when it reaches 195° F, the thermostat opens.
3. The hot coolant now circulates between the radiator and the engine with the thermostat open.
4. Even tho' the thermostat has opened, the temperature of the coolant will continue to increase.
5. All the while, the engine coolant temperature is continually monitored and reported to the fuel injection computer by the engine coolant temperature (ECT) sensor.
6. When the computer sees the ECT sensor reporting a temperature of around 220° F, it commands the radiator fan ON.
7. The engaged fan now pulls more air across the radiator, cooling the coolant within it.
8. Since the thermostat is open, the cooler coolant in the radiator enters the engine to cool it down.
9. As the coolant's temperature decreases further, the fan is commanded OFF, and the thermostat closes.
10. The coolant in the engine now begins to absorb more heat, and the process repeats itself continually the whole time the engine is running.

More 2.2L Beretta, Cavalier, Corsica, And Sunfire Diagnostic Tutorials

If this tutorial was helpful, be sure and take a look at all of the 2.2L Beretta, Cavalier, Corsica, And Sunfire diagnostic tutorials in this index:

• GM 2.2L Index Of Articles.

Here's a sample of the tutorials you'll find there:

• How To Test The Fuel Pump (1992-1997 2.2L Beretta, Cavalier, Corsica, Sunfire).
• How To Test The TPS (1992-1997 2.2L Beretta, Cavalier, Corsica, Sunfire).
• How To Test The Front Oxygen Sensor With A Multimeter (2.2L GM).
• How To Test The GM 2.2L Ignition Coil Pack.