Question 213Motor Plants - 1st Asst/Chief

The correct answer is B) Not less than 30 minutes. After stopping a diesel engine due to a high main bearing temperature, it is recommended to wait at least 30 minutes before opening the crankcase. This is to allow the engine and its components to cool down sufficiently, as the bearing surfaces and oil may still be very hot immediately after shutdown. Opening the crankcase too soon could result in the release of hot oil or steam, posing a safety hazard. The 30-minute waiting period helps ensure the engine has had enough time to cool, making it safe to access the crankcase and perform any necessary inspections or maintenance. The other options are incorrect because 15 minutes may not be enough time for the engine to cool down adequately, while 60 and 120 minutes are longer than the recommended 30-minute waiting period.