USCG Exam PracticeDiesel engine principles (motor propulsion)
Before performing any internal maintenance work on a marine diesel engine, which combination of preparatory steps is required?
- A. Reduce engine to idle speed, close the fuel day-tank valve, and post a watch at the throttle
- ✓ Stop and cool the engine, isolate starting air and fuel, and engage the turning gearCorrect
- C. Stop the engine, drain the jacket-water system, and lock the throttle in the closed position
- D. Shut down the engine, depressurize the lube-oil system, and remove the cylinder heads
Why B is correct
Before any internal work the engine must be stopped, cooled, the starting air and fuel isolated, and the turning gear engaged so the engine cannot roll. Engaging the turning gear is specifically required to prevent inadvertent rotation, which could injure personnel working inside the engine. Draining the jacket water and removing heads are task-specific steps, not universal prerequisites.
Cited:NAVEDTRA 14075 §3-1