During hydraulic system diagnostics, what does a significant temperature differential across a hydraulic valve indicate?

A significant temperature differential across a hydraulic valve indicates internal leakage or restriction within the valve. Hydraulic valves control the flow and pressure of hydraulic fluid. When a valve is functioning correctly, there should be minimal pressure drop and therefore minimal temperature change as fluid passes through it. However, if there is internal leakage (fluid passing from a high-pressure area to a low-pressure area within the valve without performing useful work) or a restriction....