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单选题
Icreasing the exhaust valve tappet clearance of a diesel engine will result in the exhaust valve opening （）
A
later and closing earlier
B
later and closing later
C
earlier and closing earlier
D
earlier and closing later
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During the valve overlap period, the exhaust pressure of a turbocharged four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure ______.A.effective cylinder scavenging and coolingB.constant pressure from the turbochargersC.cooler operation of the exhaust systemD.effective constant pressure for turbocharger operation
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单选题Which of the following problems represent one possible cause of high lube oil consumption in a four stroke diesel engine?（）A
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单选题White smoke issuing from the exhaust of an auxiliary diesel engine valve opening （）A
the engine is overloadedB
the engine is coldC
there is too much lube oil in the cylindersD
the turbocharger is fouled
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单选题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 shaftB
compressed air pressureC
hydraulic “push rods”D
direct action of the main piston moving down
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单选题If the relief valve on a diesel engine cylinder lifts, the cause could be due to （）A
liquid in the cylinderB
low compression in the cylinderC
high exhaust temperatureD
poor fuel penetration
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单选题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-strokeA
(1) only is correctB
(2) only is correctC
both (1) and (2) are correctD
Neither (1) or (2) are correct
考题
单选题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 cylinderB
incorrectly adjusted intake valve timingC
incorrectly adjusted fuel injectorD
incorrectly adjusted intake valve clearance
考题
单选题Many diesel engine exhaust valves are being constructed with hollow stems filled with sodium in order to （）A
provide added wear protection against today’s corrosive quality of fuelB
increase overall valve strength due to the high gas pressuresC
assist in dissipating heat due to the extreme operating temperaturesD
reduce the overall weight of the valve thus helping eliminate valve spring surge and hammering
考题
单选题A dark exhaust from a running diesel engine can be caused by （）A
late ignitionB
water in the fuelC
high compression temperatureD
starting valve stuck open
考题
单选题The size of the exhaust valve opening is （）A
most critical in a four-stroke cycle diesel engineB
most critical in a two-stroke/cycle diesel engineC
most critical in a four-stroke/cycle diesel engine if it is turbochargedD
of equal importance in a two-stroke/cycle diesel engine as in a four-stroke/cycle diesel engine
考题
单选题When the normal compression ratio of a diesel engine is not very high, misfiring at light loads may be caused by （）A
overloading the engineB
low exhaust valve liftC
excessive cylinder coolingD
insufficient mechanical clearance
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单选题Excessively worn, or polished ends on a diesel engine valve spring, indicate（）A
burned exhaust valvesB
excessive spring compressionC
spring surgeD
worn valve seats
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单选题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 coolingB
constant pressure from the turbochargersC
cooler operation of the exhaust systemD
effective constant pressure for turbocharger operation
考题
单选题"Scavenging" on a diesel engine means （）.A
injecting fuel oil into a cylinderB
removing exhaust gases from the cylinderC
forcing air into the cylinders under pressure after the exhaust valve has dosedD
a combination of all the above
考题
单选题Exhaust valve openings in a diesel engine cylinder head are made as large as practical to （）A
increase back pressure during the exhaust processB
facilitate periodic replacement of the valvesC
reduce the pumping loss associated with scavengingD
reduce tension on valve springs
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单选题Clearance volume scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished （）.A
during the valve overlap periodB
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without cooling the cylinders or pistons
考题
单选题The arrangement and shape of the cams on a diesel engine camshaft directly control which of the listed groups of operating conditions?（）A
speed, torque, and horsepower productionB
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fuel consumption, efficiency, and cylinder pressureD
scavenge pressure, compression ratio, and exhaust pressure
考题
单选题A large two-stroke/cycle direct reversing diesel engine is to be reversedPrior to the admission of starting air you must （）A
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reposition the fuel injection camC
change the intake and exhaust valve cam positionsD
place the starting cam in the intermediate position
考题
单选题Diesel engine valve springs function to （）A
hold the valves openB
keep the valves off their seats until the exhaust stroke is completedC
close the valvesD
open inlet valves when the air injection cycle begins
考题
单选题Valve lash, or clearance refers to the （）A
clearance between the top of the valve stem and the rocker armB
compression of the valve springsC
clearance between the valve seat inserts and the headD
out of roundness of the fuel injection cams
考题
单选题Low compression pressure in a diesel engine may be the result of （）A
insufficient fuel supply due to fuel pump valves sticking or leakingB
excessive mechanical clearance between the piston crown and cylinder headC
excessively worn fuel pump plungerD
excessive exhaust back pressure
考题
单选题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 gasesB
energy supplied to the turbochargerC
air pressure to the intake manifoldD
purge of exhausted gases from the cylinders
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单选题Scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished（）A
during the valve overlap periodB
with only the exhaust valve openC
at a pressure below atmosphericD
without cooling the cylinders or pistons
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单选题In a diesel engine, an extremely leaking exhaust valve can cause （）.A
misfiringB
pre-ignitionC
interrupted scavengingD
reduced scavenging
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单选题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 spaceB
equalize cylinder and exhaust manifold pressuresC
alleviate the difference in valve size between the intake and exhaustD
flush out condensate that collects after each compression stroke
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