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Which of the following precautions must be taken if an electric immersion heater is used to keep the coolant in a diesel engine warm during the time the engine is secured?

  • A.The coolant temperature must be maintained at 180℃
  • B.The thermostatic bypass valves must be manually opened before the engine is started
  • C.The pressure cap must be removed while the engine is secured
  • D.Electrical power to the heater must be secured before the cooling system is drained
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