单项选择题Under normal conditions, the main source of crankcase oil contamination is attributed to ()

A.metal particles loosened by wear
B.air when air cleaners are not used
C.condensation of water vapors
D.breakdown of the lubricating oil by dilution


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1.单项选择题Valve cages are used on some large diesel engines to ()

A.reduce wear on the valve stem
B.permit the use of alloy valve seat materials
C.reduce heat transfer from the valve seat
D.facilitate valve removal for servicing

2.单项选择题If the jacket water temperature rises rapidly above normal in a diesel engine, you should FIRST ()

A.place standby cooler in operation
B.reduce engine load
C.check thermostatic valve
D.clean sea water strainer

3.单项选择题Which of the following conditions can cause excessive lube oil consumption in a diesel engine?()

A.Low lube oil temperature
B.Dirty lube oil strainer
C.Low lube oil pressure
D.High lube oil temperature

4.单项选择题In the common rail system, excessive pressure in the header may be caused by ()

A.improper adjustment of the bypass valve
B.a dribble in the fuel injection nozzle
C.insufficient leak-off through injection nozzle packing
D.a malfunctioning injection nozzle

5.单项选择题Diesel engine valve springs function to ()

A.hold the valves open
B.keep the valves off their seats until the exhaust stroke is completed
C.close the valves
D.open inlet valves when the air injection cycle begins

6.单项选择题Worn diesel engine intake valve guides can result in ()

A.increased engine breathing efficiency
B.excessive valve lash
C.excessive lube oil consumption
D.lower than normal fuel consumption

8.单项选择题Excessive piston ring wear in a diesel engine will cause()

A.high lube oil viscosity
B.increased lube oil consumption
C.low lube oil temperatures
D.high firing pressures

9.单项选择题In the voyage, when carrying out abandon ship drill, should be test every time().

A.the emergency lighting system for muster and abandon ship
B.air/oil emergency shut-down
C.M-Eemergency operation
D.main/auxiliary steering gear changing