Product Overview Fan pump / auxiliary cooling piston pump designed for Hitachi excavators ZAX870-5G, ZAX870-5B, and ZX670LC-5G. This pump supports the auxiliary cooling circuit, ensuring stable hydraulic fan operation and reliable thermal management under demanding working conditions. Part numbers: YA00011362 | 4700708 | 9313598 Common Failures Fan stops running: Solenoid failure, worn valve plate, piston seizure. Overheating: Excessive internal leakage, swash plate wear,