Sierra Oil Seal 18-0579, Replaces Mercury 26-41131, White

The Sierra 18-0579 Oil Seal is a rubber powerhead seal engineered to seal rotating shafts against oil and water intrusion in marine outboard and sterndrive powerheads. It is built to meet or exceed the specifications of the original equipment part it replaces, making it a reliable direct-fit choice for engine rebuilds and routine seal replacement. The seal is molded in white rubber and sized to a 1.313 inch outer diameter, a 1.141 inch shaft size, and a 0.344 inch width, allowing it to seat correctly in the powerhead bore while maintaining a tight, low-friction fit against the shaft. As a wear item, this seal is commonly replaced during powerhead teardowns, gearcase service, or whenever oil seepage is found around the shaft. It cross-references directly to Mercury and Chrysler/Force/US Marine part number 26-41131, giving buyers a straightforward way to confirm fit against their original part number before ordering.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-0579
• Product Type: Oil Seal
• Material: Rubber
• Color: White
• Outer Diameter: 1.313 inches
• Shaft Size: 1.141 inches
• Width: 0.344 inches
• Weight: 0.04 pounds
• OEM Cross Reference: 26-41131

Fitment

Direct cross-reference to Mercury and Chrysler/Force/US Marine part number 26-41131; confirm against your original part number before ordering.

Replaces (OEM)

• 26-41131

Frequently Asked Questions

What does the Sierra 18-0579 Oil Seal replace? The Sierra 18-0579 Oil Seal is a direct cross-reference to Mercury and Chrysler/Force/US Marine part number 26-41131.

What are the dimensions of the 18-0579 seal? This seal measures 1.313 inches outer diameter, 1.141 inches shaft size, and 0.344 inches in width.

What material is the 18-0579 Oil Seal made from? It is molded from rubber for durable sealing against oil and water in marine powerheads.

What color is the Sierra 18-0579 seal? The 18-0579 seal is white.

How much does the Sierra 18-0579 Oil Seal weigh? This seal weighs 0.04 pounds.

Is the Sierra 18-0579 seal equivalent to the original equipment part? Yes, Sierra states this oil seal meets or exceeds the original equipment part it replaces, part number 26-41131.

Where is the 18-0579 seal typically installed? It is installed in the powerhead bore to seal a rotating shaft, and is commonly replaced during powerhead or gearcase service.

How many seals come in an order of 18-0579? The Sierra 18-0579 Oil Seal is supplied as a single unit.

Why would I need to replace this seal? Oil seepage or leakage around the shaft during a powerhead teardown is the typical reason to replace the 18-0579 seal.

Does the 18-0579 seal fit non-Mercury applications? It cross-references to Mercury and Chrysler/Force/US Marine 26-41131, so any application originally using 26-41131 is a match.