4655038 Original Excavator Oil Temperature Radiator for Hitachi ZX870-3

Part number 4655038 corresponds to Oil Cooler (commonly known as "oil temperature radiator/hydraulic oil cooler core assembly") in Hitachi's original cooling system part number system, and is often labeled as compatible with large excavators such as Hitachi ZAX850-3 and ZAX870-3 (and associated with platform derived model numbers/variants) in public channel information. It belongs to the exclusive parts of the cooling system, not the engine water tank or the universal vulnerable parts, so it cannot be used interchangeably across models based on its "similar appearance"; Regular procurement should use Hitachi EPC to lock the drawing number of the part, and verify the overall machine model+body serial number+cooling module/pump valve configuration code. If necessary, provide photos of the old core and installation interface dimensions for secondary verification.
 

As the core of the original oil temperature cooler, its main function is to remove the heat from the return/lubrication circuit. The common structure is an aluminum plate fin (Bar Plate/Plate Fin) or copper aluminum composite core, which is equipped with vibration resistant heads, connection interfaces (flanges/threads), and mounting feet at both ends of the core. The internal oil passage is separated from the external air passage to ensure reliable sealing, sufficient heat transfer area, and balance pressure and vibration resistance. The key point of the original parts is not whether they can dissipate heat, but strictly controlling the core thickness/core width/center distance of the connecting pipe and the geometry of the sealing surface according to the drawings. It can maintain the stability of hydraulic oil viscosity, reduce pump valve leakage and seal aging under high dust, high vibration, and large temperature difference (heat dissipation temperature difference is often greater than 40-60 ℃) conditions of the excavator.

Performance warning: If the hydraulic oil temperature remains high for a long time (such as continuously approaching/exceeding the manual alarm threshold), or if the pressure difference between the inlet and outlet of the cooler is abnormally large but the fan is normal, first check the oil cleanliness/filter element and system overflow, and then check whether the core body is locally blocked or slightly leaking.   

Key points for replacement: Release pressure and clean the surrounding sediment before disassembly and assembly; Ensure that the connecting rubber ring/sealing surface is undamaged during installation, and that the bolts are tightened in a cross order with the specified torque (tightening too tightly may cause deformation and leakage of the installation feet/heads); If the core body is found to have collapsed and blocked the air channel, the fins are extensively inverted, the connecting pipe thread is slipping, or there is obvious leakage, it is safer to directly replace it with the original factory 4655038. It is not recommended to knock and shape it to "extend its life".