Excavator Hydraulic Pump 708-3D-00020 708-3D-01020 708-3D-00030 Komatsu PC138US-8, PC120-8, PC110-8, PC130-8 Main Piston Pump Common Faults Weak digging power when hot: Internal leakage caused by worn pistons, cylinder block and valve plate. Engine lugging: Stuck PC valve or malfunction of EPC solenoid valve. Slow actions & high oil temperature: Stuck LS valve or worn pump internals. Abnormal noise & vibration: Cavitation, damaged bearing or piston shoe. Large case drain flow