Identify a common symptom of a hydraulic leak.

A common symptom of a hydraulic leak is the presence of an external fluid puddle or a decrease in system performance. When hydraulic fluid leaks from a system, it can pool on the ground or surface beneath the equipment, clearly indicating that fluid is escaping. This visual cue is often one of the first signs noticed by operators or maintenance personnel.

Additionally, the loss of hydraulic fluid impacts the system's ability to maintain pressure and perform efficiently, leading to a decrease in overall performance. This might manifest as slower actuations, reduced lifting capacities, or even complete operational failure if the leak is severe enough. Therefore, observing a fluid puddle along with noting reduced system performance are direct indicators of a hydraulic leak and prompt the need for further investigation and repair.

Other options like increased operational noise, frequent system distress signals, and excessive heating of the fluid can also point towards issues within a hydraulic system, but they are more indicative of operational problems that may or may not be directly related to a leak.