The electronic thermostat of BMW generally starts to open automatically when the temperature at the engine's coolant inlet reaches 103 degrees Celsius, without requiring DME control. Function of the thermostat: The thermostat serves to save energy consumption. Its specific role is to remain closed when the vehicle's temperature has not yet reached the normal operating temperature, allowing the engine coolant to circulate only in the upper part of the radiator. This helps the engine to warm up quickly, as operating at low temperatures is highly fuel-consuming and causes the most damage to the vehicle. Once the temperature exceeds the normal operating range, the thermostat opens, enabling the coolant to circulate throughout the entire radiator (large circulation), facilitating rapid heat dissipation. Principle of the thermostat: The primary type of thermostat used is the wax-type thermostat. When the coolant temperature is below the specified value, the wax inside the thermostat's temperature-sensing element remains in a solid state, and the thermostat valve, under the action of a spring, closes the passage between the engine and the radiator. The coolant then returns to the engine via the water pump. When the coolant temperature reaches the specified value, the wax begins to melt and gradually turns into a liquid. Once the engine's coolant temperature rises above 80 degrees Celsius, the main valve of the thermostat automatically opens. At this point, the coolant flowing out from the water jacket passes through the radiator for cooling before being sent back to the water jacket by the water pump (large circulation). This enhances the cooling intensity of the heat dissipation system, effectively preventing the engine from overheating.
