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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 cylinder
B
incorrectly adjusted intake valve timing
C
incorrectly adjusted fuel injector
D
incorrectly adjusted intake valve clearance
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更多 “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” 相关考题
考题
If the diesel engine fuel injection timing is changed to delay the start of injection until the pistons are at top dead center, the engine will_________.A.backfire through the air intakesB.develop less power under loadC.have high firing pressuresD.lift its cylinder relief valves
考题
第一组Older loop scavenged engines may have a single injector mounted centrally in the cylinder head. Because the exhaust valve is in the center of the cylinder head on modern uniflow scavenged engines the fuel valves (2 or 3) are arranged around the periphery of the head. The pressure at which the injector operates can be adjusted by adjusting the loading on the spring. The pressures at which the injectors operate vary depending on the engine, but can be as high as 540 bar. Some injectors have internal cooling passages in them extending into the nozzle through which cooling water is circulated. This is to prevent overheating and burning of the nozzle tip. Injectors on modern engines do not have internal cooling passages. They are cooled by a combination of the intensive bore cooling in the cylinder head being close to the valve pockets and by the fuel which is re-circulated through the injector when the follower is on the base of the cam or when the engine is stopped. As well as cooling the injector, re-circulating the fuel when the engine is stopped keeps the fuel at the correct viscosity for injection by preventing it from cooling down. Fuel injectors must be kept in good condition to maintain optimum efficiency, and to prevent conditions arising which could lead to damage within the cylinder. Injectors should be changed in line with manufacturers recommendations, overhauled and tested. Springs can weaken with repeated operation leading to the injector opening at a lower pressure than designed. The needle valve and seat can wear which together with worn nozzle holes will lead to incorrect atomization and dribbling.Modern uniflow scavenged engines have______.A.a single injector mounted in the center of the cylinder headB.several injectors mounted around the external boundary of the cylinder headC.a single injector mounted at the external boundary of the cylinder headD.several injectors mounted in the center of the cylinder head
考题
Fuel is admitted to a diesel engine cylinder through the ______.A.injector nozzlesB.carburetorC.exhaust portsD.intake valves
考题
One cylinder of a diesel engine is persistently knocking and does not cease(停止) when the fuel supply to that cylinder is secured.Which of the following problems may be the cause?A.Low loading of the cylinderB.Excessive cooling of that pistonC.Sluggish ring action on the pistonD.A mechanical defect in a working part
考题
In a diesel engine, late fuel injection is indicated by black or gray exhaust smoke with ______.A.low firing pressureB.low exhaust temperatureC.mechanical knock in each cylinderD.fuel knock in each cylinder
考题
单选题Worn diesel engine intake valve guides can result in （）A
increased engine breathing efficiencyB
excessive valve lashC
excessive lube oil consumptionD
lower than normal fuel consumption
考题
单选题To successfully reduce an excessively high diesel engine exhaust gas temperature, you should （）.A
reduce the engine driven fuel pump outlet pressureB
retard the fuel injector timing to reduce powerC
increase the fuel rack settingD
reduce the load on the engine
考题
单选题The consistent burning of fuel oil with a high sulfur content in a diesel engine will result in （）A
clogged fuel injection pumpsB
increased cylinder liner wearC
intake valve stem corrosionD
varnish deposit on pistons
考题
单选题A practical way of checking for excessive fuel injection in one cylinder of an operating diesel engine is to （）A
feel the high pressure fuel lineB
check the cylinder exhausts for white smoke frequentlyC
check the cylinder exhaust temperatureD
isolate each cylinder and inspect the injector
考题
单选题In a diesel engine, late fuel injection is indicated by black or gray exhaust smoke with（）A
low firing pressureB
low exhaust temperatureC
mechanical knock in each cylinderD
fuel knock in each cylinder
考题
单选题If a single cylinder relief valve on a main propulsion diesel engine begins to lift, but it is not possible to secure the engine, which of the following actions should be taken?（）A
Increase the cooling water flow to the engineB
Secure or reduce fuel to that cylinderC
Screw down on the pressure adjusting spring to decrease to decrease popping pressureD
Readjust the injection timing
考题
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
考题
单选题If the firing pressures in a diesel engine are high, although the exhaust temperatures are normal, the cause may be（）A
early injection timingB
worn orifices in the injection nozzlesC
worn or scored cylinder linersD
using a fuel with too low of a cetane number
考题
单选题Significant retardation of a diesel engine fuel injection timing will result in （）A
smoother engine operationB
advanced fuel ignitionC
increased fuel economyD
reduced engine power
考题
单选题Which of the conditions listed could cause the cylinder relief valves on a large, low-speed, propulsion diesel engine to lift?（）A
Plugged injector nozzlesB
Excessive fuel injectionC
Very late injection timingD
Incorrect crankshaft clearance
考题
单选题If a diesel engine is smoking excessively under load, the cause could be （）A
low exhaust back pressureB
early fuel injection in one of the cylindersC
compression pressure in one of the cylindersD
plugged injector holes
考题
单选题Broken intake valve springs on one cylinder of a diesel engine can cause the engine to （）A
Over speedB
fire improperlyC
lose oil pressureD
overheatrapidly
考题
单选题A change in the quality of fuel atomization by a diesel engine fuel injector would be caused by a/an （）A
increase in engine speedB
increase in cylinder turbulenceC
leaking needle valveD
reduction in cylinder turbulence
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
line up the engine fore restarting with light diesel oilB
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Late fuel injection in a diesel engine is indicated by low firing pressure with（）A
high exhaust temperatureB
low exhaust temperatureC
fuel knock in each cylinderD
mechanical knock in each cylinder
考题
单选题One remedy for a high firing pressure, in addition to a high exhaust temperature in one cylinder of a diesel engine, is to （）A
increase scavenge air pressureB
reduce fuel booster pump pressureC
adjust the fuel rackD
retard fuel injector timing
考题
单选题If the diesel engine fuel injection timing is changed to delay the start of injection until the pistons are at top dead center, the engine will（）A
backfire through the air intakesB
develop less power under loadC
have high firing pressuresD
lift its cylinder relief valves
考题
单选题Late fuel injection occurring at, or after TDC in a diesel engine is indicated by excessive exhaust smoke and （）A
low exhaust temperatureB
low firing pressureC
fuel knock in each cylinderD
mechanical knock in each cylinder
考题
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
考题
单选题The timing of diesel engine air starting valves is controlled by（）A
the air start valve timing gears and rodsB
a cylinder check valveC
individual cams and valve gearD
an air manifold poppet valve
考题
单选题Diesel engine fuel oil contamination often results in （）A
governor malfunctionsB
fuel injection system malfunctionsC
high cylinder lube oil temperaturesD
low intake temperatures
考题
单选题Failure to open the diesel engine test cocks after a long period of shutdown, prior to starting may result in （）A
an air bound fuel systemB
damage to cylinder heads and pistonsC
excessive fuel injectionD
excessive air valve lift
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