Question 442Motor Plants - Assistant Engineer

The correct answer is A) engine overload. High exhaust temperature and black smoke from a diesel engine are typically caused by incomplete combustion due to engine overload. When the engine is operating beyond its designed capacity, it requires more fuel to maintain the desired power output. This excess fuel does not fully combust, leading to high exhaust temperatures and the production of black, sooty exhaust. The other options are incorrect because low combustion temperature (B) would result in incomplete combustion and white/blue smoke, a plugged fuel nozzle (C) would cause poor atomization and irregular combustion, and excessive compression pressure (D) would not directly lead to high exhaust temperature and black smoke.