Question 366General Subjects - QMED

The correct answer is C) air trapped in the system. When the hydraulic system of a deck winch has been drained, flushed, and refilled with hydraulic fluid, an erratic knocking noise from the hydraulic motor when the winch is started indicates the presence of air trapped in the system. Air trapped in the hydraulic lines can cause cavitation and erratic operation of the hydraulic motor, leading to the observed knocking noise. The other options are incorrect because: A) A high fluid level in the reservoir would not cause a knocking noise. B) Clogged suction line filters would restrict flow, but not necessarily cause a knocking noise. D) Abrasive matter circulating in the oil would cause wear and tear, but not necessarily a knocking noise.