单项选择题
A.immediately open all crankcase relief ports
B.increase crankcase exhauster speed to draw cool air into the engine
C.allow the engine to cool naturally
D.increase crank case scavenge air to remove unburned gases
单项选择题 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?（）
单项选择题 Which of the following statements is true regarding the installation of piston rings on two-stroke/cycle, diesel engines as compared to four-stroke/cycle, diesel engines?（）
单项选择题 If a crankcase explosion occurs in a diesel engine, which of the listed actions should be taken?（）