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In a medium speed diesel engine, a trunk type piston may be cooled by（） Ⅰ.oil circulation though passages in the piston crown Ⅱ.heat transfer through piston rings and liner wall
A . Ⅰ only
B . Ⅱ only
C . either Ⅰ or Ⅱ
D . neither Ⅰ or Ⅱ
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High firing pressures and a low exhaust temperature in a diesel engine may result from （）.
A . decreased piston to cylinder head clearance
B . increased exhaust system back pressure
C . early fuel injection timing
D . low scavenge air temperature
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A diesel engine may fail to start due to （）
A . low air charge temperature
B . high cranking speed
C . excessive fuel dilution of lube oil
D . high compression pressure
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If the operating element of a thermostatic valve installed in a diesel engine cooling system malfunctions, it may result in （）
A . a low level in the engine expansion tank
B . excessively high coolant pressure
C . improper temperatures
D . malfunctioning of the jacket water heater
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Defective timing gear in a diesel engine may lead to （）.
A . smoky exhaust
B . starting failure
C . overload
D . over speed
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Improper cooling of a diesel engine cylinder liner due to the accumulation of scale deposits may cause （）.
A . low compression pressure
B . increased piston wear
C . increased cylinder lube oil consumption
D . poor contact between compression rings and liner
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If water is found in the crankcase of a diesel engine, the cause may be due to（）
A . a cracked cylinder head
B . a leaky cylinder head gasket
C . a cracked cylinder liner
D . any of the above
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When starting air is admitted, a diesel engine turns over very slowly without firingThe cause may be （）
A . an obstruction in an cylinder
B . water accumulation in some engine cylinders
C . low starting air pressure
D . low scavenge air pressure
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If a single cylinder relief valve on a diesel engine lists frequently while the engine is running, the cause may be an （）
A . excessively late injection timing for each cylinder
B . incorrectly adjusted intake valve timing
C . incorrectly adjusted fuel injector
D . incorrectly adjusted intake valve clearance
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Poor combustion in a diesel engine can be caused by （）.
A . high compression pressure
B . low intake air temperature
C . low exhaust pressure
D . high scavenge air pressure
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Black smoke exhausting from an operating diesel engine is an indication of poor combustion which may be caused by （）
A . water in the fuel
B . insufficient fuel for combustion
C . clogged air intake passages
D . burning lubricating oil
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If an auxiliary diesel engine frequently stalls, the trouble may be caused by （）
A . low exhaust back pressure
B . air in the fuel system
C . gasket blow-by or leakage
D . incorrect assembly of idler spring
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The opening of an exhaust valve on a modem, large, low-speed, main propulsion diesel engine may be actuated by （）.
A . direct action of cam shaft
B . compressed air pressure
C . hydraulic “push rods”
D . direct action of the main piston moving dow
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Cold weather starting of a diesel engine may be made easier by（）
A . decreasing the compression ratio
B . using a special fuel having a high ignition temperature
C . increasing the starting air supply
D . heating the jacket water
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The following preparations are essential for any （） of marine diesel engine before it may be started.
A . doing
B . make
C . turn
D . operating
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Low compression in a diesel engine can be caused by （）
A . clogged coolant passages
B . a leaking cylinder head gasket
C . low fuel oil pressure
D . worn or broken cylinder liner sealing ring
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Diesel oil may be used to cool （） of a diesel engine.
A . cylinders
B . exhaust valves
C . pistons
D . fuel valve
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If the compression rings on a diesel engine piston become stuck in the ring groove, the cause may be due to（）
A . excessive ring action
B . excessive ring temperature
C . improper ring rotation
D . excessive ring face wear
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Defective governor in a diesel engine may lead to （）.
A . smoky exhaust
B . starting failure
C . ignition relay
D . over speed
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A restricted air intake to a diesel engine may result in the engine （）.
A . failing to reach rated speed
B . knocking under maximum load
C . hunting or surging under light load
D . overspeeding and running away
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Pistons of marine medium speed diesel engines may be made of （） in order to keep the weight down for balancing purpose at high speed.
A . lead
B . forged steel
C . alloy steel
D . aluminum alloy
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Critical speeds occurring within the operating speed range of a main propulsion diesel engine may be changed, or have their damaging effects reduced by a/an （）
A . engine support vibration isolator
B . detuner or viscous fluid damper
C . lightened crankshaft flywheel
D . spherically seated crankshaft bearing
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When the normal compression ratio of a diesel engine is not very high, misfiring at light loads may be caused by （）
A . overloading the engine
B . low exhaust valve lift
C . excessive cylinder cooling
D . insufficient mechanical clearance
