The document provides instructions for disassembling and assembling a piston pump (hydraulic fan) on a Caterpillar 336D2 GC excavator. The procedures include:
1. Removing various components of the piston motor such as bearings, seals, and housing pieces.
2. Assembling the piston pump by pressing in retaining rings, installing bearings and seals, and positioning housing pieces and mounting bolts in the correct order.
3. Installing the assembled piston pump by connecting hoses and harness assemblies, and filling the hydraulic system.