What Causes Low Engine Coolant Temperature?

[NolanFitz]

Low coolant temperature can be caused by the following reasons: 1. The thermostat, which acts as a valve component based on engine coolant temperature, is installed at the radiator outlet and water pump inlet. When the coolant temperature is low, the thermostat blocks the low-temperature coolant from the radiator, preventing it from entering the engine water jacket, allowing the water jacket temperature to rise quickly. When the coolant temperature reaches a certain level, the valve opens, allowing coolant from the radiator to circulate, slowly increasing the coolant temperature as it flows through the radiator, dissipating heat to the atmosphere and maintaining the engine at an appropriate temperature—this is known as the major circulation. If the thermostat malfunctions and the valve fails to close, the coolant remains in major circulation, potentially causing the engine temperature to be too low. Alternatively, some vehicles may have their thermostats removed during summer to reduce high temperatures, which can also result in very low engine coolant temperatures. 2. Electrical faults causing the electric fan to run continuously, or failure of the silicone fluid fan or silicone fluid clutch, can lead to constant fan operation.