How to Test Whether a Thermostat is Good or Bad?

[LaTravis]

The methods to test whether a thermostat is good or bad are: 1. Feel the temperature of the upper and lower radiator hoses by hand. Start the engine for 3 minutes, then touch the hoses. It is normal if the upper hose is hot while the lower one remains cool; 2. When the engine coolant temperature reaches 90°C, if both the upper and lower hoses are hot, it proves the thermostat is functioning properly. If the temperatures of both hoses remain the same after starting the engine, the thermostat is faulty. A thermostat is a valve that controls the flow path of engine coolant. It automatically regulates the amount of coolant entering the radiator based on the coolant temperature to ensure the engine operates within an appropriate temperature range, playing roles such as energy saving. It must maintain good working condition; otherwise, it will affect the normal operation of the engine.