Question 44 DDE01 - Designated Duty Engineer - Unlimited HP

The Correct Answer is D. **Why Option D is Correct:** Option D states: "Do not allow the engine to be started until the cause of the water discharge has been determined and corrected." When preparing a large diesel engine (like those found on a river push boat) for starting, the procedure of rolling it over with the cylinder test valves (indicator cocks) open is a crucial safety step known as "clearing" the cylinders. This expels any incompressible fluids (fuel, oil, or water) that might have accumulated above the pistons. If an incompressible fluid is present in large quantities, attempting to start the engine will result in hydraulic lock (hydro-lock) when the piston attempts to reach top dead center (TDC). Since the fluid cannot be compressed, the resulting immense pressure will cause catastrophic damage to the engine components, such as bent connecting rods, cracked cylinder heads, or a broken block. A "rather large amount of water" being discharged is a significant warning sign that there is a major leak, usually indicating a failure in the cooling system (e.g., a cracked cylinder liner, a faulty cylinder head gasket, or a damaged O-ring seal) allowing jacket cooling water to leak directly into the combustion space. Starting the engine without fixing this issue risks: 1. Catastrophic mechanical failure (hydro-lock) upon compression. 2. Severe damage to the bearings and lubricating system if water gets into the crankcase. 3. Overheating due to the loss of cooling water, even if the engine manages to run briefly. Therefore, the engine must be inspected, the source of the leak identified (e.g., pressure testing the cooling system), and the necessary repairs completed before attempting any start. **Why the Other Options are Incorrect:** * **A) Start the engine, but monitor all fluid levels very closely, especially that of the jacket water.** This is irresponsible and dangerous. Monitoring fluid levels will only confirm that the engine is actively destroying itself or losing coolant rapidly. It does not mitigate the immediate risk of hydro-lock from water remaining in the cylinders, nor does it address the underlying serious mechanical fault. * **B) Start the engine, but maintain the jacket water expansion tank level higher than normal.** Increasing the expansion tank level might temporarily delay the low-water alarm, but it encourages more cooling water to leak into the cylinder spaces due to the increased static head pressure. This increases the risk of hydro-lock and does not address the fundamental failure that caused the leak. * **C) Start the engine, but run the engine with the cylinder test valves cracked slightly open.** Running an engine with the test valves open is extremely hazardous. It allows pressurized hot combustion gases (and flame) to escape directly into the engine room, creating a severe fire and burn hazard. It also significantly reduces cylinder compression, leading to poor performance, excessive smoke, and potential damage to the valve seats and threads of the test valves. This is never an acceptable operational procedure.