Sierra 18-2026 Oil Seal, Replaces OMC 321453, for Evinrude/OMC Outboard Prop and Driveshaft

The Sierra 18-2026 is a nitrile oil seal engineered for Evinrude and OMC outboard prop and driveshaft applications. It is built to maintain a reliable barrier against water intrusion and lubricant loss at the driveshaft and propeller shaft interface, helping protect the lower unit gearcase from corrosion and premature wear. The seal is molded from solid nitrile material in a white finish, sized to install as a direct replacement in the gearcase housing where the original equipment seal has hardened, cracked, or begun to leak. Nitrile construction offers good resistance to marine gear lubricants, saltwater, and the temperature swings typical of outboard lower unit service, making it a durable choice for routine gearcase maintenance and seal replacement work. This seal directly interchanges with OMC part number 321453 and cross-references to Mallory number 9-76203, giving installers a straightforward way to confirm fit when working from an OEM or Mallory part number instead of the Sierra number. It ships as a single seal, ready to be pressed into the gearcase during a standard lower unit service or seal kit replacement. Because gearcase seals are wear items that should be replaced any time the lower unit is opened up, keeping the correct Sierra 18-2026 on hand is a practical step for anyone maintaining an Evinrude or OMC outboard prop and driveshaft assembly.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2026
• Product Name: Oil Seal
• Material: Nitrile
• Item Form: Solid
• Color: White
• Item Dimensions: 5 x 4.02 x 0.98 inches
• Weight: 0.02 pounds
• UPC: 030999309723
• Application: Evinrude Outboard Prop and Driveshaft Seal
• OEM Cross Reference: OMC 321453; Mallory 9-76203

Fitment

Designed for Evinrude and OMC outboard prop and driveshaft seal applications.

Replaces (OEM)

• OMC 321453
• Mallory 9-76203

Frequently Asked Questions

What does the Sierra 18-2026 oil seal replace? The Sierra 18-2026 is a direct replacement for OMC part number 321453 and cross-references to Mallory number 9-76203, so it can be ordered using any of these part numbers.

What is the Sierra 18-2026 used for? It is an oil seal designed for Evinrude and OMC outboard prop and driveshaft applications, sealing the gearcase to keep water out and lubricant in.

What material is the 18-2026 seal made from? It is made from solid nitrile, a material chosen for its resistance to marine gear lubricants, saltwater exposure, and the temperature range seen in outboard lower units.

What color is the Sierra 18-2026 oil seal? The Sierra 18-2026 oil seal is white.

What are the dimensions of the Sierra 18-2026? The Sierra 18-2026 measures 5 x 4.02 x 0.98 inches.

How much does the Sierra 18-2026 oil seal weigh? This oil seal weighs 0.02 pounds.

Is the Sierra 18-2026 an OEM part or aftermarket? The 18-2026 is a Sierra-branded aftermarket seal manufactured to replace OMC 321453 and cross-reference to Mallory 9-76203, rather than an OEM OMC or Mallory part.

How many seals come in a package? The Sierra 18-2026 is sold as a single oil seal, one unit per package.

Can I use the Mallory 9-76203 number to find this part? Yes, Mallory number 9-76203 cross-references directly to the Sierra 18-2026 oil seal.

Will the 18-2026 seal fit my Evinrude or OMC outboard? The Sierra 18-2026 is designed for Evinrude and OMC outboard prop and driveshaft seal applications; confirm fit using the OMC 321453 or Mallory 9-76203 cross-reference numbers for your specific gearcase.

How is the 18-2026 oil seal installed? It presses into the gearcase housing at the prop shaft or driveshaft bore as part of a standard lower unit seal replacement, typically done whenever the gearcase is opened for service.

Why does this seal need to be replaced periodically? Gearcase seals like the Sierra 18-2026 wear and can harden or crack over time, which allows water intrusion or lubricant loss, so replacing them during routine lower unit service helps prevent gearcase damage.