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单选题
Cracking of a diesel piston crown can result from（）
A
Excessive piston to liner clearance
B
The underside of the piston crown being excessively dirty lowering the rate of heat transfer
C
Faulty nozzle spray
D
All of the above
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单选题A diesel engine cylinder head can crack as a result of （）A
a leaking seal ringB
heat transfer from exhaust valvesC
restricted cooling passagesD
overheated intake valves
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单选题Worn main bearings in a diesel engine can result in （）A
decreased compression pressureB
increased lube oil pressureC
lower lube oil temperatureD
excessive leakage past the piston rings
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单选题“The use of a poor quality oil can lead to rapid deterioration of its properties with the resultant formation of deposits in the piston crown which in turn results in a considerable reduction in heat transfer with subsequent overheating and thermal cracking” According to this sentence, we can know that the principle reason of the overheating and thermal cracking is（）A
the use of a poor quality oilB
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the formation of depositsD
the reduction in heat transfer ability
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单选题Scuffed cylinder liner wearing surfaces in a diesel engines can result from （）A
starting the engine while hotB
knurling the piston skirtC
operating the engine overheatedD
scuff resistant piston rings
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单选题White smoke exhausting from a diesel engine can result from （）A
high exhaust temperatureB
high lube oil temperatureC
low turbo-charger speedD
low cooling water temperature
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单选题Cracking of a diesel piston crown can result from（）A
Excessive piston to liner clearanceB
The underside of the piston crown being excessively dirty lowering the rate of heat transferC
Faulty nozzle sprayD
All of the above
考题
单选题The diameter of a piston is usually less at the crown than at the skirt, in order to （）.A
facilitate the installation of piston ringsB
allow for the expansion of the piston during operationC
prevent crankcase vapors from entering the combustion chamberD
reduce wearing of the upper cylinder liner
考题
单选题Scuffed cylinder liner wearing surfaces in a diesel engines can result from （）A
chromium plating piston ringsB
knurling the piston skirtC
extended maximum power operationD
applying load to a cold diesel engine
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单选题Incomplete combustion in a running diesel engine can cause piston rings to become stuck as a result of （）A
residual carbon depositsB
lube oil viscosity breakdownC
uneven heat expansion of the ringsD
uneven heat expansion of the piston
考题
单选题In a four-cycle diesel engine piston blow-by can result in increased（）A
crankcase pressureB
compression pressureC
scavenge pressureD
exhaust manifold pressure
考题
单选题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 wallA
Ⅰ onlyB
Ⅱ onlyC
either Ⅰ or ⅡD
neither Ⅰ or Ⅱ
考题
单选题When inspecting piston rings through the ports of a two-stroke/cycle diesel engine, black areas on the sealing surfaces are the result of （）A
insufficient lubricationB
improper piston coolingC
blow-byD
overload operation
考题
单选题Low compression of diesel engine may result from （）A
a worn cylinderB
broken piston ringsC
any of A and BD
none of the above
考题
单选题In a trunk type diesel engine piston, the thickness of the head or crown is determined by the（） Ⅰ.statically balanced Ⅱ.heat dissipation requirementA
Ⅰ onlyB
Ⅱ onlyC
both Ⅰ and ⅡD
neither Ⅰ nor Ⅱ
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单选题High firing pressures and a low exhaust temperature in a diesel engine may result from （）.A
decreased piston to cylinder head clearanceB
increased exhaust system back pressureC
early fuel injection timingD
low scavenge air temperature
考题
单选题Scuffed cylinder liner surfaces in a diesel engine can result form（）A
starting the engine hotB
knurling the piston skirtC
operating an overheated engineD
using scuff resistant piston rings
考题
单选题The function of the piston compression rings used in a diesel engine is to （）A
seal the space between the piston and linerB
transmit heat from the piston to the cylinder linerC
reduce the amount of combustion gas blow-byD
all of the above
考题
单选题Persistent knocking of one cylinder of a diesel engine ceases when the fuel supply to that cylinder is securedThis problem may be a result of （）A
low loading of that cylinderB
faulty combustion in that cylinderC
sluggish piston ring actionD
excessive piston cooling
考题
单选题In a large, low-speed diesel engine the clearance between the piston crown and cylinder head is found to be excessiveIn order to correct for this, you should（）A
build up the piston crown by metal sprayingB
build up the cylinder head by metal sprayingC
insert shims between the crankpin bearing box and the connecting rod footD
install a thinner head gasket
考题
单选题Persistent knocking in one cylinder of a diesel engine could be caused by（）.A
a low load on that cylinderB
sluggish piston ring actionC
excessive piston crown coolingD
excessive clearance of piston pin
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Engine coolant accumulating in the diesel engine lubricating oil can result from a （）A
low oil pressureB
high coolant pressureC
leaking fuel injectorD
cracked cylinder head or liner
考题
单选题The rotary motion of a diesel engine crankshaft is obtained from the up and down motion of the piston via the （）.A
camshaftB
reduction gearsC
rocker armD
connecting or piston rod
考题
单选题In diesel engines designed with a crosshead, the motion of the piston rod can be described as （）.A
reciprocating at the piston pin, rotary at the crank pinB
reciprocating at the crank pin, rotary at the piston pinC
straight reciprocationD
straight rotation
考题
单选题The function of diesel engine piston compression rings is to （）.A
prevent piston side thrustB
prevent engine friction lossesC
transmit heat from the piston to the cylinder linerD
remove oil from the cylinder combustion space
考题
单选题Piston compression rings used in a diesel engine function to （）A
transfer heat from the cylinder to the pistonB
scrape oil from the sides of the pistonC
seal the combustion space from the crankcasesD
prevent any piston contact with the cylinder liner
考题
单选题Diesel engine piston seizure can be caused by （）A
poor cooling of cylinder wallsB
improper cooling of the pistonC
insufficient piston lubricationD
all of the above
考题
单选题A diesel engine piston crown can crack from （）A
excessive piston to liner clearanceB
excessive dirt beneath the piston crown that reduces heat transferC
faulty nozzle sprayD
all of the above
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