Question 369Motor Plants - Assistant Engineer

The correct answer is C) 165° to 180°F. The recommended operating water jacket outlet temperature range for medium-speed marine diesels set up with closed treated fresh water cooling systems and fitted with vented expansion tanks is typically 165° to 180°F. This temperature range is commonly specified by engine manufacturers and industry standards as the optimal operating conditions for this type of cooling system. Temperatures outside this range could indicate issues with the cooling system or engine performance. The other options are incorrect because A) 105° to 120°F is too low, B) 135° to 150°F is still too low, and D) 195° to 215°F is too high for the recommended operating temperature range of medium-speed marine diesels with this type of cooling setup.