MDE 4 End of Unit Quiz

MDE 4 End Of Unit Quiz

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5. Maintenance of Air Coolers

Question: What is an important maintenance task for ensuring the efficient operation of air coolers in a turbocharged diesel engine?

C) Reducing the engine's operating temperature

A) Regularly replacing the turbocharger

D) Adding fuel additives to the diesel fuel

B) Cleaning the air cooler to remove any buildup of dirt or oil

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Turbocharger Lubrication

Question: How is a turbocharger typically lubricated in a marine diesel engine?

A) By injecting grease directly into the turbocharger bearings

B) By circulating engine lubricating oil through the turbocharger bearings under pressure

C) By using a separate lubrication system dedicated to the turbocharger

D) By mixing lubricating oil with the fuel before combustion

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Purpose of the Nozzle Ring in Turbochargers

Question: What is the primary purpose of the nozzle ring in a main engine turbocharger?

D) To increase the pressure of intake air before it reaches the compressor wheel

B) To direct and accelerate exhaust gases onto the turbine wheel for improved energy extraction

A) To regulate the flow of lubricating oil to the turbocharger bearings

C) To cool the exhaust gases before they enter the turbine

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Components of a Resilient/Flexible Engine Mounting

Question: In a cross section through a resilient/flexible mounting for a diesel engine, what are the MAIN components typically found? (Select THREE)

C) Engine support beams

A) Mounting brackets

D) Rubber or elastomeric pads

F) Fastening bolts

E) Shock absorbers

B) Vibration isolators

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3. Cooling Medium for Air Coolers

Question: What medium is commonly used to cool the air in an intercooler fitted after a turbocharger?

C) Ambient air

A) Exhaust gases

B) Engine coolant (water or antifreeze)

D) Fuel oil

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5. Possible Cause: Boost Control Issues

Question: What boost control issue could lead to a decrease in boost pressure in a turbocharged engine?

B) A failing battery

A) A faulty wastegate or boost control valve

D) A clogged fuel filter

C) A broken starter motor

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Purpose of Zinc Anodes in Air Coolers

Question: What is the purpose of zinc anodes in air coolers?

A) To enhance the cooling efficiency of the air cooler

D) To reduce the noise generated by the air cooler

C) To increase the pressure of the air passing through the cooler

B) To prevent corrosion by providing a sacrificial material that corrodes instead of the cooler components

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5. Turbocharger Efficiency

Question: How can the efficiency of a turbocharger be improved?

A) By increasing the fuel injection pressure

B) By optimizing the turbine and compressor design to reduce energy losses

C) By reducing the size of the exhaust manifold

D) By decreasing the engine's RPM

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4. Turbocharger and Exhaust Gases

Question: What role do exhaust gases play in the operation of a turbocharger?

C) They cool the turbocharger to prevent overheating

A) They are recirculated into the intake manifold to reduce emissions

D) They are vented directly to the atmosphere without any impact on the turbocharger

B) They power the turbine, which drives the compressor

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Purpose of the Diffuser in Turbochargers

Question: What is the primary purpose of the diffuser in a main engine turbocharger?

D) To filter the intake air before it enters the compressor wheel

C) To reduce the backpressure in the exhaust system and improve turbocharger efficiency

B) To slow down the high-velocity air exiting the compressor and convert its kinetic energy into pressure

A) To increase the temperature of the compressed air before it enters the cylinders

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4. Maintenance of Pulse Systems

Question: What is an important maintenance consideration for ensuring the proper function of a pulse system in a turbocharged engine?

B) Ensuring proper alignment and integrity of the pulse piping and valves

A) Regularly replacing the turbocharger bearings

D) Adjusting the engine’s timing to match pulse frequencies

C) Increasing the fuel injection pressure to compensate for pulse system inefficiencies

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Location of Thrust Bearing in Turbochargers

Question: Where is the thrust bearing typically fitted in a large medium-speed diesel engine turbocharger?

D) At the intake manifold to reduce air pressure fluctuations

C) On the shaft between the compressor side and the bearing housing

B) On the exhaust manifold to support the turbocharger housing

A) Between the compressor wheel and the turbine wheel

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