Question 47Motor Plants - QMED

The correct answer is C) scavenging air. In large, low-speed, main propulsion diesel engines, the scavenging air is typically cooled using sea water. The scavenging air is the fresh air that is forced into the engine cylinder to push out the exhaust gases, and cooling this air helps improve the engine's efficiency and performance. The other answer options are incorrect because: A) the cylinder heads are usually cooled by engine coolant, not sea water; B) the exhaust valves are cooled by engine coolant, not sea water; and D) the injectors are not directly cooled by sea water in this type of engine.