CAT 5J-4991 OEM Piston Seal Assembly Kit Caterpillar 5J4991 165mm Bore

Prevent internal fluid bypass and sustain peak dynamic power within your heavy-duty cylinder configurations with this Genuine OEM Caterpillar (CAT) 5J-4991 Hydraulic Piston Seal Assembly Kit.

Engineered as a high-performance, 2-piece active system, this authentic kit consists of a premium Teflon-profile outermost piston ring paired with a specialized nitrile elastomeric expander. This structural layout provides dependable low-friction fluid separation between the rod and cap ends of high-pressure dynamic cylinders operating above 3,000 PSI.

Product Specifications:

• Part Number: 5J-4991 (Also referenced as 5J4991)
• Component Type: 2-Piece Piston Seal Assembly
• Kit Contents: Includes 1x 5J-4592 Face Seal Ring and 1x 5J-4593 Expander Ring
• Bore Diameter: 165.0 mm (6.50 in)
• Groove Diameter: 141.99 mm (5.59 in)
• Groove Width: 9.65 mm (0.38 in)

Compatible Heavy Equipment Configurations:

Extensively integrated into heavy machinery lines requiring high-pressure 165mm cylinder bores, including:

• CAT Crawler Dozers / Track-Type Tractors: D5B, D6D, D6H, D6R, D6T, D7G, D7H, D7R, D8N, D8R, D8T, D9N series tracking frameworks.
• CAT Wheel Loaders & Loaders: 966C, 966R, 980, 988, 951, 955, 963, 977K, and 977L.
• CAT Wheel Scrapers & Earthmoving Compactors: 631C, 631D, 631E, 631G, 633C, 633D, 637E, 637G, 666, 824C, and 836.
• System Groups: Compatible with select CAT Ripper assemblies, Winch controls, and 153/163 Hydraulic Controls.

Condition & Packaging Details:

• Condition: New Old Stock (NOS) surplus inventory. Brand new, uninstalled, and completely clean.
• Packaging Notes: Shipped in its original manufacturer packaging. Outer protective film, bags, or labeling may display minor cosmetic dust, warehouse markings, or shelf storage wear. Packs are intermittently inspected for catalog photography.
• What You Receive: The exact genuine Caterpillar component shown in our listing image array.

Shipping & Return Policies:

• Fitment Verification: Please ensure cross-reference check against your specific machine arrangement serial prefix or parts manual diagrams before checking out.
• Shipping: Safe, reliable logistics options are calculated instantly at checkout. Expedited delivery speeds are available for rapid repairs.
• Returns: Returns are accepted seamlessly. Buyer retains return shipping parameters unless a variation error occurs directly on our part.