Caterpillar 8J-4386 O Ring

Caterpillar 8J-4386 is an OEM Cat O-ring molded from nitrile (NBR) with a 90A hardness rating, designed for hydraulic sealing in Caterpillar tilt cylinders. The catalog lists the size as 5.33 mm cross-section by 199.39 mm inside diameter, providing a precise seal path to prevent leaks under typical Cat hydraulic pressures. Used in tilt cylinder assemblies, the 8J-4386 seal sits between the cylinder body and adjacent components to maintain fluid containment and reliable operation of the tilt mechanism. As a Cat part, it adheres to Cat sealing standards and is compatible with Cat hydraulic systems and the fluids specified for heavy equipment operation. The O-ring's nitrile formulation offers good resistance to mineral-based hydraulic fluids and suitable performance across the temperature ranges seen on construction sites. When replacing, ensure the groove width and seating surface match the 5.33 mm cross-section and inner diameter of 199.39 mm to maintain proper compression and seal integrity. The 8J-4386 O-ring is intended for use in Cat tilt cylinders as part of hydraulic service on Caterpillar machines, ensuring a properly sealed interface between the cylinder and its components.