What is a sign of cavitation in a hydraulic pump?

Increased noise and vibration is indeed a sign of cavitation in a hydraulic pump. Cavitation occurs when vapor bubbles form in the liquid being pumped and subsequently collapse, causing shock waves that lead to significant noise and vibration within the pump. This phenomenon typically arises when the pressure within the pump drops below the vapor pressure of the hydraulic fluid, causing the fluid to vaporize. The resulting bubble collapsions can create destructive forces that not only lead to the mentioned noise and vibration but can also cause damage to the pump components over time.

Understanding that noise and vibration are indicators allows operators to monitor pump performance effectively and take corrective actions before further damage occurs. The other options do not accurately reflect the typical signs or effects associated with cavitation.