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In an operating diesel engine, which of the following condition is an indication of a leaking air starting valve?（）
A . noise coming from that air starting valve
B . continuous operation of the starting air compressor
C . zero air pressure in the air starting system
D . overheated starting air pipe to the cylinder head
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A turbocharged, four-stroke/cycle diesel engine has a larger valve overlap than a naturally aspirated four-stroke/cycle diesel engine, in order to in crease the （）.
A . temperature of the exhaust gases
B . energy supplied to the turbocharger
C . air pressure to the intake manifold
D . purge of exhausted gases from the cylinder
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If you were inspecting the valve springs on an auxiliary diesel engine, your best indication of impending spring failure would be （）
A . a glazed surface on the spring
B . nicks in the protective coating
C . a build up of sludge deposits
D . cracks in the surface of the spring
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In a four-stroke cycle diesel engine the intake valves open （）
A . before TDC and close after BDC
B . after TDC and close after BDC
C . before TDC and close before BDC
D . after TDC and close before BDC
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The loss of the diesel engine cylinder air charge through leaky valves, piston rings, worn or scored liners, would be indicated by which of the following sets of conditions?（）
A . Low compression pressure and high exhaust temperature
B . Low firing pressure and high exhaust temperature
C . Low compression pressure and low exhaust temperature
D . Low firing pressure and low exhaust temperature
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In the cylinder head of a two-stroke/cycle diesel engine, valves are used for（）
A . air intake
B . a fuel outlet
C . cooling water inlets
D . exhausting combustion ga
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During the valve overlap period, the exhaust pressure of a turbochargers, four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure （）
A . effective cylinder scavenging and cooling
B . constant pressure from the turbochargers
C . cooler operation of the exhaust system
D . effective constant pressure for turbocharger operatio
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Which of the following methods is used to prevent throttling of compressed air through the diesel engine air starting valves?（）
A . Holding the valve open for a long period
B . Increasing the starting air pressure used
C . Opening the stating air valve quickly
D . Reducing the starting air valve size
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A loud clicking noise from the valve compartment of an operating diesel engine would indicate（）
A . worn valve seats
B . worn main bearing
C . excessive valve clearance
D . weak rocker arm spring
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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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A three-way thermostatic control valve regulates the diesel engine cooling water temperature by passing a portion of the water （）.
A . around the engine
B . around the cooler
C . to the expansion tank
D . overboard
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A two-stroke diesel engine exhaust temperature will be lower than a four-stroke diesel engine of the same displacement because the （） (1) MEP is lower and the scavenging air is cooling the exhaust gases (2) valve overlap in a four-stroke
A . (1) only is correct
B . (2) only is correct
C . both (1) and (2) are correct
D . Neither (1) or (2) are correct
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The intake valves in a diesel engine are reseated by （）.
A . cam followers
B . push rods
C . combustion gases
D . valve spring
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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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Excessive valve lash in an auxiliary diesel engine will cause the valves to open（）
A . later and close sooner
B . sooner and close later
C . sooner and close sooner
D . later and close later
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The satisfactory operation of diesel engine exhaust valves usually depends on（）
A . the proper back pressure
B . the cooling water temperature
C . correct timing and proper seating
D . accurate metering and the exhaust temperature
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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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For an ordinary four-stroke diesel engine the exhaust valves close （）.
A . after TDC
B . before TDC
C . after BDC
D . before BDC
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In a diesel engine, exhaust valves open before the intake ports are uncovered to （） Ⅰ.reduce pumping losses Ⅱ.reduce back pressure
A . Ⅰonly
B . Ⅱonly
C . bothⅠand Ⅱ
D . neitherⅠnor Ⅱ
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If the relief valve on a diesel engine cylinder lifts, the cause could be due to （）
A . liquid in the cylinder
B . low compression in the cylinder
C . high exhaust temperature
D . poor fuel penetratio
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The timing of diesel engine air starting valves is controlled by（）
A . the air start valve timing gears and rods
B . a cylinder check valve
C . individual cams and valve gear
D . an air manifold poppet valve
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Diesel engine air start valve timing is controlled by（）
A . engine operating speed
B . an air manifold
C . a hydraulic distributor
D . individual cams and valve gear
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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 consumptio
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In a turbocharged four-stroke/cycle diesel engine, the exhaust valve remains open until after top dead center and the intake valve opens before top dead center to_______.
A.produce a scavenging effect in the combustion space
B.equalize cylinder and exhaust manifold pressures
C.alleviate the difference in valve size between the intake and exhaust
D.flush out condensate that collects after each compression stroke
