8970715611 Original Isuzu 4JJ1 Engine Crankshaft Oil Seal (rear) for Excavator Parts 

Part number 8970715611 (also commonly written as 8-9071561-1) is a special part number for the crankshaft rear oil seal of Isuzu's original 4JJ1 series diesel engine. This oil seal is a key static sealing component at the junction between the rear end of the engine crankshaft and the flywheel housing or gearbox. Its main function is to prevent the internal oil of the engine from leaking out from the rear end of the crankshaft, while isolating external dust, moisture and other impurities from entering the engine interior, ensuring the normal operation of the lubrication system and protecting the core moving parts. As an original standard component, it is mainly suitable for Hitachi hydraulic excavators equipped with Isuzu 4JJ1 engines, such as Hitachi ZX100-3, ZX120-3, ZX140W-3, ZX160-3, ZX180-3 and other models.
 

The crankshaft rear oil seal is a typical skeleton oil seal, which belongs to the core component of the engine crankshaft sealing system. Its core structure is composed of a synthetic rubber sealing lip that is resistant to oil, high temperature, and aging, and is tightly combined with a metal skeleton that plays a supporting and positioning role through vulcanization process. The sealing lip is designed with a main sealing lip and a dust-proof lip. The main sealing lip relies on its interference fit and spring clamping force to tightly adhere to the high-speed rotating crankshaft journal, forming a dynamic seal; Dust lips prevent external impurities from entering. As an original component, it adopts high standard materials and production processes specified by Isuzu, ensuring excellent dimensional accuracy, outstanding elastic recovery ability, excellent wear resistance, and long-term stable sealing performance. It can withstand high temperatures inside the engine (up to 150 ° C or more), oil corrosion, and friction and centrifugal force caused by high-speed crankshaft rotation (thousands of revolutions per minute), which is the basis for ensuring long-term leak free operation of the engine.
 

The maintenance core of this oil seal lies in regularly checking for signs of leakage, seizing the opportunity for replacement, and standardizing installation operations. Replacing oil seals is a technically demanding task. Disassembling the old oil seal requires the use of a specialized puller to avoid damaging the crankshaft journal and mounting hole. Before installation, the crankshaft journal and oil seal seat hole must be thoroughly cleaned to ensure that there are no burrs, oil stains, or residual old sealant. The sealing lip and shaft neck of the new oil seal need to be coated with an appropriate amount of clean engine oil for installation and initial lubrication. During installation, a suitable specialized installation tool (such as a sleeve) must be used to press the oil seal vertically and evenly into the hole. It is strictly prohibited to directly strike the metal shell of the oil seal. After installation, tighten the relevant connecting bolts to the specified torque and run the engine to check for any remaining leaks. It is recommended to have experienced professional technicians perform the operation.