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Cavitation erosion in the cooling water system of a diesel engine usually occurs at the pump impeller, and on the waterside of the （）
A . fuel nozzle holders
B . exhaust value guides
C . engine cylinder liners
D . low temperature and a low viscosity
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Cooling the intake air supplied to a diesel engine will （）.
A . reduce mean effective pressure
B . decrease average compression pressure
C . decrease air charge density
D . increase power output
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The pH value of water in a diesel engine closed cooling water system should be maintained between （）.
A . 60 to75
B . 80 to 95
C . 100 to 115
D . 120 to 135
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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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If the cooling water temperature and the lube oil temperature in a diesel engine are too high, the cause can be （）
A . a dirty lube oil strainer
B . internal water leaks
C . an oil suction line restriction
D . excessive wears of the cooling water pum
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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 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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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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In a diesel engine cooling system, the high temperature alarm contact maker will be activated on excessively high water discharge temperature from the （）
A . raw water pump discharge
B . expansion tank outlet
C . cooling water heat exchanger
D . outlet engine jacket water outlet
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One of the purposes for water cooling the exhaust manifold in marine diesel engine is to （）
A . reduce lube oil temperature
B . raise exhaust temperature reduce
C . excessive heating of engine room
D . reduce load on cooling water pum
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In a closed cooling system for a turbocharged, four-stroke/cycle diesel engine, fluctuating water pressure can be caused by （）
A . improper venting of the cooling system
B . carrying the expansion tank water level too high
C . a totally clogged impeller in the cooling water pump
D . an incorrectly set cooling system temperature control
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A large, low-speed, main propulsion diesel engine uses sea water to directly cool the （）.
A . cylinder heads
B . exhaust valves
C . scavenging air
D . injector
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A diesel engine cooling water system with a pH factor of 30 indicates a condition of （）.
A . slight acidity
B . slight alkalinity
C . excessive alkalinity
D . excessive acidity
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The jacket water temperature in a diesel engine closed freshwater cooling system is normally controlled by （）
A . regulating the level of corrosion inhibitor in the primary cooling system
B . the level of the freshwater expansion tank
C . varying the engine load to meet temperature requirements
D . the operation of the thermostatic valve
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In a diesel engine exhaust system, the cooling of the exhaust gases below their dew point, will result in （）
A . increased engine back pressure
B . sulfuric acid corrosion
C . surface pitting of the turbocharger
D . moisture impingement on the turbocharger compressor blade
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（） providing lubricating films, oil used in marine diesel engines have to remove heat from oil cooled piston.
A . Except for
B . Beside
C . Except
D . In addition to
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The most serious effect of air trapped in a diesel engine jacket water cooling system is that it（）.
A . causes colloid suspension in the cooling water
B . reduces the capability of the lubrication system
C . can form pockets which block the flow of coolant through the system
D . leads to the scuffing of cylinder wall
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Which of the following problems can cause fluctuating pressures in the closed cooling system of a main propulsion diesel engine?（）
A . Defective temperature controls in the system
B . Cavitation in the cooling water pump
C . Opened vent in the cooling system
D . Restricted water passages in the engine
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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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In a diesel engine, an integral liner is one in which the cooling water （） Ⅰ.flows through the cylinder liner jackets Ⅱ.touches the outer side of the liner
A . Ⅰ only
B . Ⅱ only
C . both Ⅰ and Ⅱ
D . neither Ⅰ and Ⅱ
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Which of the following problems can cause an above normal air temperature to develop in the intake manifold of a turbocharged and after-cooled diesel engine?（）
A . Faulty turbocharger turbine diffuser ring
B . Faulty turbocharger compressor ring
C . Insufficient cooling water flow
D . Clogged air intake filter
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Some diesel engines are fitted with a thermometer in the cooling water outlet from each cylinderIf the cooling water temperature from all cylinders begins to rise above normal, you should suspect （）
A . increase blow-by in all cylinders
B . incomplete combustion in all cylinder
C . overloading in all cylinders
D . insufficient fuel delivery to all cylinder
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The purpose of treating the cooling water of the diesel engine is to（） Ⅰ. resist the scale formation in the cooling chamber Ⅱ.lubricate the engine part Ⅲ.increase thermal capacity Ⅳ.resist corrosion
A . Ⅰ+Ⅱ
B . Ⅱ+Ⅲ
C . Ⅲ+Ⅳ
D . Ⅰ+Ⅳ
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After-cooling of a turbocharged diesel engine will result in （）
A . higher torque but lower brake horsepower
B . lower torque but higher brake horsepower
C . higher torque and lower brake horsepower
D . lower torque and higher brake horsepower
