Insufficient system pressure, weak lifting and bucket curling
Abnormal noise and heavy vibration of hydraulic pump, cavitation sound
Excessive internal pump leakage, rapid oil temperature rise
Damaged pump shaft seal, external oil leakage on pump
Stuck displacement control mechanism, abnormal flow regulation
Worn pistons and cylinder block, reduced volumetric efficiency
Scuffed valve plate, severe pressure fluctuation
Air ingestion in suction line, foamy hydraulic oil
Worn servo valve, slow displacement response
Damaged bearing, knocking noise during pump operation
Procurement Recommendations
Perform case drain flow test first to assess wear condition. Replace complete hydraulic pump assembly if pistons, cylinder block or valve plate are severely scuffed. Purchase piston kit and repair kit for rebuilding in case of minor wear.
Verify OEM part number strictly before purchase. Check pump housing for cracks, sand holes and deformed flange surface. Select high-quality seal kit to prevent premature shaft seal failure. Check condition of displacement control valve and servo valve, purchase separately if required.