Excavator Hydraulic Pump 708-27-04023 708-27-04022 Komatsu PC400-3 PC410-5 PC300-5 PC400-5 Main Piston Pump Product Overview High-performance main piston hydraulic pump designed for Komatsu excavator models PC400-3, PC410-5, PC300-5, and PC400-5. Compatible with part numbers 708-27-04023 and 708-27-04022. Common Faults & Diagnostics Weak digging power when hot: Internal leakage from worn pistons, cylinder block and valve plate Engine lugging: Stuck or misadjusted TVC torque