MDE 4 End of Unit Quiz

MDE 4 End Of Unit Quiz

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1. Possible Cause: Air Leak

Question: What is one possible cause of reduced boost pressure at the inlet manifold in a turbocharged engine fitted with a charge air cooler?

D) Excessive engine oil consumption

B) An air leak in the intake system or charge air cooler

C) A faulty fuel injector

A) A clogged air filter

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Purpose of the Diffuser in Turbochargers

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

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

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

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

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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?

D) Fuel oil

B) Engine coolant (water or antifreeze)

A) Exhaust gases

C) Ambient air

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3. Troubleshooting Pulse System Issues

Question: What could be a symptom of a problem with the pulse system in a turbocharged diesel engine?

B) Reduced engine responsiveness and increased turbo lag

A) Increased engine noise and vibration

D) Increased coolant temperature

C) Decreased engine oil temperature

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Special Considerations for Engine Installation with Resilient/Flexible Mountings

Question: What is a special consideration necessary with respect to engine installation when using a resilient/flexible mounting for a diesel engine?

A) Ensuring the engine is perfectly aligned with the drive shaft

C) Ensuring adequate ventilation around the engine

D) Properly securing the resilient/flexible mounts to prevent excessive movement and alignment issues

B) Regularly checking and adjusting the engine oil level

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4. Consequence of a Faulty Air Cooler

Question: What is a likely consequence if an air cooler fails or becomes inefficient on a turbocharged diesel engine?

D) Improved fuel economy and lower engine emissions

B) Lower exhaust gas temperature and reduced power output

C) Higher intake air temperature, leading to reduced engine efficiency and increased risk of knocking

A) Increased engine cooling efficiency

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Indications of Poor Turbocharger Performance

Question: What are possible indications of poor turbocharger performance? (Select FOUR)

E) Decreased engine coolant temperature

A) Increased turbo lag and delayed acceleration

F) Reduced power output and overall engine performance

B) Excessive exhaust smoke or black smoke from the engine

D) Unusual whining or rattling noises from the turbocharger

C) Higher engine oil temperature than usual

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Turbocharger Lubrication

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

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

D) By mixing lubricating oil with the fuel before combustion

A) By injecting grease directly into the turbocharger bearings

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

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Purpose of the Thrust Bearing in Turbochargers

Question: What is the primary purpose of the thrust bearing in the construction of a diesel engine turbocharger?

C) To cool the turbocharger by directing airflow through the bearing housing

A) To support the radial load of the rotating components and reduce friction

B) To absorb and manage the axial forces generated by the high-speed rotation of the turbocharger shaft

D) To increase the intake air pressure before it reaches the engine cylinders

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Lubrication of Thrust Bearing in Turbochargers

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

B) By engine coolant circulating through the bearing housing

D) By the engine’s lubricating oil system, which circulates oil through the turbocharger bearing housing

A) By grease that is manually applied during maintenance intervals

C) By a dedicated oil pump that supplies pressurized lubricating oil directly to the bearing

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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?

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

C) Reducing the engine's operating temperature

D) Adding fuel additives to the diesel fuel

A) Regularly replacing the turbocharger

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Possible Causes of Poor Turbocharger Performance

Question: What are possible causes of poor turbocharger performance? (Select FOUR)

D) A worn-out or damaged turbocharger turbine

F) Low engine oil level

A) A clogged air filter

B) A malfunctioning fuel injector

E) A restricted exhaust system

C) An air leak in the intake system

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