Question 50 DDE01 - Designated Duty Engineer - Unlimited HP

The Correct Answer is B. ### Explanation for Option B (5) **B) 5:** Item number 5 in standard marine engine lubricating oil schematics (such as MO-0183) represents the **Lubricating Oil Filter**. The filter is a critical component positioned in the main oil flow path, typically after the pump (which pressurizes the oil) and often after the cooler. Its function is to remove abrasive contaminants, such as metal particles and soot, from the oil before the oil is distributed to sensitive components like bearings, pistons, and gears, thereby preventing wear and ensuring engine longevity. ### Explanation for Incorrect Options **A) 2:** Item 2 typically represents the **Lubricating Oil Pump**. The pump draws oil from the sump/reservoir and pressurizes the oil to send it through the rest of the system (cooler, filter) and ultimately to the engine components. **C) 10:** Item 10 commonly represents the **Lubricating Oil Cooler (Heat Exchanger)**. This component removes excess heat absorbed by the oil during circulation, ensuring the oil remains within its optimal operating temperature range. **D) 12:** Item 12 frequently identifies the **Sump/Oil Pan/Reservoir** (where the oil is stored) or an indicator device, such as a pressure or temperature gauge, placed either before or after the main distribution manifold. It is not the filter.