Hydraulic System Diagnostics
Pump whining, cylinder drift, slow functions, jerky operation, overheating, oil analysis, and contamination monitoring.
- Diagnose hydraulic pump noise including cavitation and aeration
- Identify causes of cylinder drift and slow hydraulic functions
- Explain hydraulic oil analysis and contamination standards
- Troubleshoot hydraulic system overheating
- Diagnose hose failures and jerky hydraulic operation
Leçon 1
Pump Diagnostics & Noise Analysis
Diagnosing Hydraulic Pump Problems
The hydraulic pump is the heart of the system. When it fails or degrades, every function is affected. Pump problems often present as noise, slow operation, or complete loss of hydraulic function. Learning to identify pump-related symptoms is essential for efficient troubleshooting.
Cavitation Noise
Rattling, gravel-like sound
Air bubbles collapsing inside pump
Caused by restricted suction line
Plugged suction strainer or collapsed hose
Aeration Noise
Whining, erratic sound
Air entering the suction side
Loose suction fittings or low oil
Foamy oil visible in tank sight glass
Cavitation vs. Aeration
Both cavitation and aeration introduce air or vapor into the pump, but the causes differ. Cavitation occurs when the pump cannot draw enough oil - a restriction on the suction side creates a vacuum that causes oil to vaporize. Aeration occurs when external air enters through loose connections, low oil level, or a damaged seal. Both destroy pumps rapidly if not corrected.
Pump Destruction
Cavitation and aeration cause rapid pump wear and failure. Metal erosion on pump surfaces, scoring on pistons, and pitting on valve plates are all signs of air in the system. Fix the root cause immediately.
Pump Flow Testing
A pump flow test measures actual pump output and compares it to specifications. Connect a flow meter and load valve to the pump output. As load increases, flow should remain steady until the relief valve opens. If flow drops significantly under load, the pump is worn and bypassing internally.
Cavitation sounds like rattling gravel and is caused by suction restrictions. Aeration sounds like whining and is caused by air entering the system. A pump flow test under load reveals internal pump wear - more than 10-15% flow drop under load indicates a worn pump.