單項選擇題Diesel engine mufflers or silencers reduce the engine exhaust noise by （）

A.passing the exhaust through long head pipes
B.diffusing exhaust vibrations through activated carbon baffles
C.increasing the exhaust gas velocity
D.reducing the exhaust gas velocity


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1.單項選擇題If a diesel engine were running at 20% overload with a smoky exhaust, you should（）

A.stop the engine immediately to prevent damage
B.increase lube oil pressure
C.slow the engine allowing it to gradually cool
D.decrease the cooling water it temperature to the water jacket

2.單項選擇題A substantial increase pressure could be an indication of a/an （）

A.worn cylinder liner
B.faulty cylinder relief valve
C.excessive lube oil pressure
D.excessive scavenge air pressure

3.單項選擇題A water jacket is placed around the exhaust manifolds of propulsion diesel engines to（）

A.reduce heat radiation to the engine room
B.aid in preventing turbocharger overheating
C.condense and drain moisture from exhaust gases
D.dampen exhaust gas pulsations in the manifold

4.單項選擇題An increase in diesel engine crankcase pressure generally indicates excessive（）

A.compression pressure
B.lube oil header pressure
C.scavenge air pressure
D.piston ring blow-by

5.單項選擇題You are inspecting the lower main precision bearings on a diesel engine.You observe that about half the thin Babbitt linings are of a milky white colourThis condition is caused by （）

A.large dirt particles in the oil supply
B.insufficient lubricating oil and overheating
C.normal wear
D.water contamination of the lube oil