MDE 10 End of Unit Quiz

A) Increases oil viscosity and leads to foaming: Incorrect. Water typically reduces oil viscosity and can cause foaming.

B) Promotes corrosion and rust formation on engine components: Correct. Water contamination leads to rust and corrosion.

C) Enhances the oil’s cleaning and dispersant properties: Incorrect. Water does not enhance cleaning properties; it can harm them.

D) Improves the oil’s cooling capacity: Incorrect. Water does not improve oil cooling; it can cause damage.

Correct Answers: A) Inadequate oil flow or circulation
B) Excessive friction due to worn or misaligned gears
C) High ambient temperature
E) Insufficient oil level

Explanation:

• Inadequate oil flow or circulation: Poor circulation can prevent effective cooling of the oil and gearbox components, leading to higher temperatures.
• Excessive friction due to worn or misaligned gears: Increased friction from worn or misaligned gears generates more heat, raising the oil temperature.
• High ambient temperature: An elevated ambient temperature can affect the gearbox's cooling efficiency, leading to higher oil temperatures.
• Insufficient oil level: Low oil levels can reduce the effectiveness of lubrication and cooling, causing the temperature to rise.

Note: While an overfilled oil reservoir and a faulty temperature sensor can affect gearbox performance, they are less direct causes of excessive oil temperature compared to the listed answers.

Correct Answer: B) Metallic particles

Explanation: Metallic particles can enter the lubricating oil as a result of wear and tear of engine components such as bearings, gears, and other moving parts. These particles can cause abrasion and increase engine wear.

Correct Answer: B) Ensuring proper filtration and regular filter changes

Explanation: Proper filtration and regular filter changes help to remove contaminants that can lead to sludge and deposits in the oil, keeping the oil clean and in good condition.

Explanation:

• A) Reduces friction between moving parts: Correct. Lubricating oil forms a film between moving parts to reduce friction, which minimizes wear and improves engine efficiency.
• B) Acts as a coolant to lower engine temperatures: Correct. Lubricating oil helps to carry away heat from the engine components, contributing to overall engine cooling.
• C) Cleans the engine by removing contaminants: Correct. Lubricating oil helps to suspend and carry away contaminants such as dirt and metal particles, preventing them from accumulating in the engine.
• D) Enhances fuel combustion efficiency: Incorrect. While lubricating oil affects engine performance, it does not directly enhance fuel combustion efficiency.
• E) Seals gaps between engine components: Incorrect. Lubricating oil does not seal gaps; it primarily reduces friction, cleans, and helps in cooling.
• F) Prevents corrosion and rust on engine parts: Correct. Lubricating oil contains additives that help to protect engine parts from corrosion and rust.

B) Ensures more uniform oil distribution and control of oil flow

Explanation: Forced circulation lubrication provides better control and uniform distribution of oil compared to splash lubrication. The use of a pump ensures that oil is delivered precisely where it is needed, including the cylinder liners, which improves lubrication efficiency and engine performance.

B) Oil is splashed onto the cylinder liners by the movement of engine components

Explanation: In splash lubrication, oil is dispersed onto the cylinder liners by the movement of rotating engine components, such as the crankshaft. This method is generally used in smaller engines or older designs, and it relies on the mechanical action to spread oil, which may not be as uniform or controlled as forced circulation.

Correct Answer: B) Condensation of water vapor

Explanation: Water contamination can occur due to condensation of water vapor inside the engine, especially in cooler environments. This can mix with the lubricating oil and degrade its performance.

Correct Answers: A) Add oil to the gearbox until it reaches the recommended level
D) Regularly check and maintain the oil level

Explanation:

• Add oil to the gearbox until it reaches the recommended level: Adding the appropriate amount of oil directly addresses the issue of insufficient oil level, ensuring proper lubrication and operation.
• Regularly check and maintain the oil level: Regular monitoring and maintenance prevent the oil level from dropping below the recommended amount, helping to avoid future problems.

Note: Installing a larger oil reservoir can be helpful but is not a direct solution to the immediate problem of insufficient oil. Decreasing the operational load or using a different type of lubricant does not address the core issue of the oil level being too low.

B) Forced circulation lubrication

Explanation: Forced circulation lubrication is a common method used in medium-speed diesel engines. This method uses a pump to circulate oil throughout the engine, ensuring a steady supply to the cylinder liners and other critical components. Splash lubrication is less common in medium-speed engines, which typically use forced circulation for better control and consistency.

A) Fuel dilution: Incorrect. Silicon is not typically associated with fuel dilution.

B) Increased wear from abrasive particles: Correct. High silicon levels indicate the presence of abrasive particles, leading to wear.

C) Increased oil oxidation: Incorrect. Silicon is not directly related to oil oxidation.

D) Higher levels of water contamination: Incorrect. Silicon contamination is not related to water levels.

B) Forced circulation lubrication

Explanation: Medium-speed diesel engines typically use forced circulation lubrication to ensure consistent oil delivery and effective cooling. This method is preferred over splash lubrication in these engines due to its ability to provide a more controlled and reliable oil supply.