Question 449Motor Plants - Assistant Engineer

The correct answer is B) Secure or reduce fuel to that cylinder. When a relief valve on a main propulsion diesel engine begins to lift, it indicates that the cylinder pressure is excessive, which can potentially lead to engine damage. The appropriate action is to secure or reduce the fuel supply to that specific cylinder in order to lower the cylinder pressure and prevent further issues. Increasing cooling water flow, adjusting the injection timing, or reducing the popping pressure of the relief valve would not directly address the root cause of the excessive cylinder pressure.