Question 14

The Correct Answer is B. ### Explanation for Option B (4) Item number 4 represents the **scavenging lube oil pump**. In a dry-sump lubrication system (common on large marine engines), the system uses two main pumps: a pressure pump and a scavenging pump. The function of the scavenging pump (4) is to draw the used lubricating oil that has drained into the engine’s sump (crankcase base) and forcefully pump it back to the main storage/settling tank (reservoir). This ensures the crankcase remains relatively free of oil, reducing aeration and drag, and prepares the oil for cooling and filtration before it is recirculated by the pressure pump. ### Why Other Options Are Incorrect **A) 2 (Incorrect)** Item 2 typically represents a component that manages heat, such as a **Lube Oil Cooler or Heat Exchanger**. This device reduces the temperature of the oil coming from the storage tank before it is supplied to the engine bearings. It is not a pump. **C) 9 (Incorrect)** Item 9 typically represents the **Main Lube Oil Pressure Pump (or Circulating Pump)**. This pump draws oil from the storage tank and delivers it under high pressure through the filters and coolers to the engine components. It handles the supply side, while the scavenging pump handles the return side. **D) 12 (Incorrect)** Item 12 typically represents the **Lube Oil Storage Tank or Reservoir**. This tank holds the bulk supply of oil, where the oil returning from the scavenging pump (4) is deposited to allow contaminants and air to settle out before the main pressure pump (9) draws it back into circulation. It is a storage vessel, not a pump.