What symptom indicates cavitation in a hydraulic pump?

Cavitation in a hydraulic pump is characterized by the formation and collapse of vapor bubbles in the fluid. This phenomenon typically occurs when the pressure in the pump falls below the vapor pressure of the hydraulic fluid. One of the most noticeable symptoms of cavitation is excessive noise from the pump. This noise results from the rapid implosion of the vapor bubbles, which creates pressure fluctuations and can produce a distinct "gravel" or "marbles" sound as the bubbles collapse.

Recognizing excessive noise is critical, as it serves as a warning sign of impending damage to the pump. If left unaddressed, cavitation can lead to significant wear on the pump components, reducing its efficiency and lifespan.

While the other symptoms listed may indicate various issues in a hydraulic system or pump operation, they do not directly point to cavitation. Low fluid temperature, milky fluid appearance, and fluid leakage at the shaft all suggest different types of problems, such as fluid contamination, improper operating conditions, or mechanical failures, rather than the specific issue of cavitation itself.