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
出自:海船船员证