Question 33 3AE01 - Third Assistant Engineer

The Correct Answer is B. ### Why Option B is Correct **B) The engine is cold:** White smoke issuing from the exhaust of a diesel engine, especially an auxiliary engine that might be starting or running at low loads, is typically unburnt or only partially burnt fuel. When the engine is cold, the combustion chamber temperature is too low to completely vaporize and ignite all the injected fuel. This raw fuel exits the cylinder as a fine mist or aerosol, which appears as dense white smoke. This phenomenon is common during engine startup in cold conditions or when the engine is struggling to reach operating temperature. ### Why Other Options Are Incorrect **A) The engine is overloaded:** An overloaded diesel engine typically produces black smoke. Black smoke is caused by excessive fuel injection relative to the available air (low air/fuel ratio), leading to incomplete combustion and the formation of soot (carbon particles). **C) There is too much lube oil in the cylinders:** Burning lube oil usually produces blue or bluish-white smoke. If lube oil were entering the combustion chamber (often due to worn piston rings or valve stem seals), it would be consumed along with the fuel, resulting in a distinct blue tint to the exhaust smoke. **D) The turbocharger is fouled:** While a fouled (dirty) turbocharger will reduce the air supply to the engine, causing a low air/fuel ratio, its primary symptom is black smoke (soot) because the engine is receiving insufficient oxygen to burn the fuel completely. It does not directly cause the white smoke associated with unburnt raw fuel.