單項(xiàng)選擇題

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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單項(xiàng)選擇題

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

單項(xiàng)選擇題

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