Electronically Heated Thermostat

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The heated thermostat is both a conventionally functioning and ECM controlled thermostat (two stage operation).

ECM control causes the thermostat to open sooner than the mechanical thermostat rating. This provides sufficient cooling for full load and high output conditions.

Fig 1: Identifying Electronically Heated Thermostat

Courtesy of BMW OF NORTH AMERICA, INC.

CONVENTIONAL FUNCTION: The thermostat begins to open at 103°C. This is at the inlet side of the water pump and represents the temperature of the coolant entering the engine.

Before the 103°C temperature is realized, the coolant is circulated through the engine block by the water pump.

Fig 2: Identifying Conventional Function Of Thermostat (1 Of 2)

Courtesy of BMW OF NORTH AMERICA, INC.

After the temperature reaches 103°C it is maintained as the inlet temperature by the thermostat. The coolant temperature at the water pump engine outlet is approximately 110°C. The additional 7°C is achieved after the coolant has circulated through the block.

The operating temperature of the engine will remain within this range as long as the engine is at part load conditions.

Fig 3: Identifying Conventional Function Of Thermostat (2 Of 2)

Courtesy of BMW OF NORTH AMERICA, INC.