Coast Guard Exams
Question 491Motor Plants - Assistant Engineer70% to pass

If the relief valve on a diesel engine cylinder lifts, the cause could be due to _______________.

AI Explanation
The correct answer is A) liquid in the cylinder. When liquid, such as water or oil, gets into the cylinder of a diesel engine, it cannot be compressed like air. This causes the pressure in the cylinder to rise dramatically, leading to the relief valve lifting to prevent damage to the engine. The other options are incorrect because low compression (B) would not cause the relief valve to lift, high exhaust temperature (C) is not directly related to the relief valve lifting, and poor fuel penetration (D) would not affect the relief valve.