Cooling （） the engine metals retain their mechanical properties.

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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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• Which of the following statements is correct for the design and installation of diesel engine cooling water systems?（）

  A . An alarm device with audible and visible signals is required for all cooling water systems B . Propulsion engines with bores over 200 mm are to be fitted with cooling water jackets C . Each totally enclosed cooling system shall be provided with a suitable head tank D . Drain cocks are to be provided at the lowest points of all cylinder water jacket

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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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• The cooling water of the diesel engine should be treated, because it has（）

  A . alkale scence B . acidity C . salinity D . impurity

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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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• Fresh water is used for the cooling of cylinder jackets and （） of the marine diesel engine.

  A . cylinder covers B . lubricating space C . crosshead D . exhaust manifold

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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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• 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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• Cooling makes the engine metals their mechanical properties（）.

  A . Remain B . to remain C . retain D . to retai

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• The cylinders, with cooling jackets, are （） to the engine frame by eight tie rods.

  A . screwed B . welded C . fastened D . rotated

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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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• About half an hour before the engine is required, cooling water at （） must be circulated.

  A . more than the working temperature B . less than the working temperature C . the working temperature D . the same as the surrounding temperature

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• During the running of the diesel engine, if the supply of cooling water is interrupted or the temperature of cooling water out of the cylinder is too high, the duty engineer should （）

  A . notify the duty officer, reduce the engine speed, take some measures to remove failures B . notify the duty officer and stop the engine immediately, find the cause and remove failures C . notify the C/E D . notify the captai

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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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• If the coolant temperature of a closed cooling water system for a diesel engine gradually increases, the trouble usually is （）

  A . a broken shaft on the freshwater pump B . an excessive accumulation of scale exchanger C . an incorrect thermostatic element operating range D . lube oil in the cooling water

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• Vents are led from the engine to the head tank for the release of （） from the cooling water.

  A . air B . heat C . sludge D . steam

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• Which of the following conditions will develop if the flow of ‘raw’ cooling water to diesel engine is obstructed?（）

  A . Air will enter the cooling system B . Carbon will plug the water cooled exhaust manifolds C . The jacket water temperature will rise D . The lube oil viscosity will increase

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• Which of the following statements is correct concerning diesel engine cooling water systems?（）

  A . Each engine must have its own engine driven cooling water pump capable of providing cooling for all ranges of operation B . propulsion engines with bores exceeding 200 mm are to be fitted with a means to display the cooling water temperature of each cylinder C . At least two independent sea suctions are to be provided for supplying water to the engine jackets or to the heat exchangers D . Suitable strain are to be fitted between the circulating pumps and heat exchangers when sea water is used for direct cooling

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• Cooling of engine is achieved by circulation a cooling liquid around internal passages within the （）.

  A . boiler B . heater C . engine D . cooler

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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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