MDE 16 Q6

Correct Answer: A. Allow the pipework to cool before handling

Explanation:
Allowing the pipework to cool before handling is a crucial safety precaution to prevent burns or injuries. Using insulated gloves (B) might be necessary, but the priority is to let the pipework cool. Increasing air pressure (C) or shutting down the engine (D) may not be necessary as an immediate safety measure compared to allowing it to cool naturally.

Correct Answer:
A. Clean or replace the air filters

Explanation:
Insufficient air supply in marine diesel engines can lead to poor combustion, resulting in black smoke and reduced engine performance. Cleaning or replacing the air filters ensures that the engine receives adequate air for combustion. Increasing fuel injection pressure, reducing engine load, or adjusting fuel injection timing do not directly address the issue of insufficient air supply.

Correct Answer:
C. Ensure the use of preheaters or glow plugs

Explanation:
Cold starting difficulties in marine diesel engines can be addressed effectively by using preheaters or glow plugs, which help warm the engine and facilitate easier ignition. Increasing engine speed, using higher viscosity engine oil, or cleaning fuel injectors might not directly resolve issues related to cold starting.

Correct Answer:
D. Reduce the fuel pump delivery rate

Explanation:
Excessive fuel injection in marine diesel engines can lead to incomplete combustion, resulting in black smoke and reduced efficiency. Reducing the fuel pump delivery rate helps control the amount of fuel injected, ensuring it matches the engine's operational needs. Adjusting the fuel injection timing, increasing engine speed, or replacing the injectors may address other issues but are not direct remedies for excessive fuel injection.

Correct Answers:
B. Burning of lubricating oil
D. Worn piston rings

Explanation:
Blue smoke in marine diesel engines is typically caused by the burning of lubricating oil, which can happen if oil leaks into the combustion chamber due to worn piston rings or other internal engine issues. Overheating of the engine, excessive fuel injection, and insufficient air supply are not directly related to the production of blue smoke.

Correct Answers:
A. Water in the fuel
E. Cold starting of the engine

Explanation:
White smoke in marine diesel engines is often caused by the presence of water in the fuel or during cold starting when the engine is not yet up to operating temperature, leading to incomplete vaporization of the fuel. Incomplete combustion and overloading of the engine are more commonly associated with other types of smoke, while high engine temperature is not directly related to white smoke.

Explanation:
Combustion defects in a diesel engine are often diagnosed by inspecting the color of the exhaust smoke. Different colors can indicate various issues, such as black smoke for excessive fuel, blue smoke for burning oil, or white smoke for incomplete combustion or coolant leaks. Checking oil pressure, coolant temperature, or battery voltage does not directly diagnose combustion defects.

Correct Answer:
A. Replace worn piston rings

Explanation:
Worn piston rings can cause lubricating oil to enter the combustion chamber, where it burns and produces blue smoke. Replacing the worn piston rings helps prevent the lubricating oil from entering the combustion chamber, thereby reducing the burning of oil. Increasing fuel injection pressure, reducing engine load, or cleaning air filters do not directly address the issue of burning lubricating

Correct Answers:
A. Excessive fuel injection
B. Insufficient air supply

Explanation: Black smoke in marine diesel engines is commonly caused by excessive fuel injection or insufficient air supply, leading to incomplete combustion. High lubricating oil pressure and coolant leaks do not typically result in black smoke, while improper fuel timing could lead to different issues such as white smoke or engine knock, but not specifically black smoke.