Question 66Motor Plants - 1st Asst/Chief

The correct answer is A) a possible overheated bearing. The purpose of an oil mist detector in a main propulsion diesel engine is to warn of a possible overheated bearing. The oil mist detector monitors the crankcase for the presence of oil mist, which can indicate a bearing failure. This early warning system allows the engine operator to investigate and address the issue before it leads to further damage. The other answer choices are incorrect because they do not accurately describe the primary purpose of an oil mist detector. Low cylinder oil pressure, excessively high crankcase vacuum, and excessive carbon buildup in the lube oil are not the main functions of an oil mist detector.