Question 56 MODE01 - Chief MODU Engineer

The Correct Answer is A **Why Option A (turbocharger malfunction or failure) is correct:** A sudden and immediate loss of power from a turbocharged diesel engine is a classic and primary symptom of a turbocharger malfunction or catastrophic failure (such as a seized or broken turbine/compressor wheel, or a catastrophic air leak in the boost plumbing). The turbocharger is responsible for forcing a large volume of pressurized air (boost) into the cylinders, significantly increasing the power output beyond what a naturally aspirated engine could achieve. If the turbocharger suddenly stops spinning or is unable to pressurize the intake air, the engine instantly reverts to operating at near-naturally aspirated levels, resulting in a dramatic, sudden, and noticeable power loss. **Why the other options are incorrect:** * **B) obstruction in the engine cylinders:** An obstruction in the cylinders (if severe enough to cause power loss) would typically result in engine misfiring, severe internal damage, or potentially a complete engine seizure, not just a sudden, uniform power reduction characteristic of a boost loss. * **C) crankcase exhauster overload:** The crankcase exhauster (part of the engine's ventilation system) manages blow-by gases. An overload would primarily indicate excessive internal pressure or blow-by, possibly leading to oil leaks or minor long-term performance degradation, but it would not cause an immediate, sudden, and massive loss of power characteristic of a boost failure. * **D) overload on the intercooler:** The intercooler (or aftercooler) cools the compressed air before it enters the engine. While a blockage or severe leak in the intercooler system would reduce power (due to loss of boost pressure or restriction), an "overload" is not a standard mechanical failure term in this context. If the intercooler simply failed to cool the air, the engine would lose some efficiency and long-term power, but it would not cause the *sudden* near-total power loss associated with a complete turbo failure.