How to determine if a 274 thermostat assembly is damaged?

Symptoms of common failures of 274 thermostat assembly:

1. Overheating or overcooling of the engine: A thermostat failure may cause abnormal engine temperature. For example, a message may appear persistently that the cooling system has not reached normal temperature or that the engine is overheated.
2. Abnormal heating or cooling function of the air conditioner: The thermostat affects the heating system, and its malfunctions may prevent the system from reaching desired temperature or lead to unstable temperature.
3. Unstable idle status or abnormal engine performance: If the thermostat fails to adjust the temperature properly, it may cause unstable idle status or abnormal engine operation.
4. Coolant leakage: Bad sealing of the thermostat may result in coolant leakage.

Methods for detection of failures of 274 thermostat assembly:

1. Observe the temperature reading on the dashboard: After the engine is started, check if the temperature is within the normal range (usually around 90°C). If the coolant temperature displayed remains low for long, the thermostat may have not been turned on. If the coolant temperature displayed remains high for long, it may have been stuck in the open position.
2. Temperature of the radiator and hoses: After the engine has run for a period of time, touch the radiator and cooling hoses:
   If the coolant has become hot but the radiator or hoses are still cold, the thermostat may have not been turned on;
   If the coolant is overheated but the radiator remains cold, the thermostat may have been stuck in the closed position.
3. Listen to the sounds: If after the engine is started, there are slight “clicking” sounds near the thermostat, the thermostat is opening and closing periodically.
4. Use a diagnostic tool: Use an OBD diagnostic tool to check if there are any related fault codes (such as those indicating a temperature sensor fault or a cooling system fault) in the engine control unit (ECU).