Sierra 18-2022 Oil Seal - Replaces OMC 303345 for Evinrude Outboard Prop and Driveshaft

The Sierra 18-2022 Oil Seal is a direct-fit replacement seal engineered for Evinrude outboard prop and driveshaft applications. This small bolt-on component seals against water and lubricant loss around the driveshaft, protecting the gearcase from water intrusion and helping maintain proper lubrication at the seal interface. It is designed as a drop-in equivalent for the OMC 303345 seal, making it a straightforward swap during gearcase service, lower unit rebuilds, or routine seal replacement.

Installation is bolt-on and does not require special tools beyond standard seal installation practice. Because seals are wear items that harden and lose sealing ability over time, replacing the 18-2022 at the first sign of water intrusion or oil seepage helps prevent more costly gearcase damage. Each unit is sold individually and is intended for one seal position per the catalog listing quantity.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2022
• Product Name: Oil Seal
• Category: Evinrude Outboard Prop and Driveshaft Seals
• Weight: 0.02 pounds
• Item Dimensions: 0.39 x 0.39 x 0.39 inches
• Installation Type: Bolt-On
• Quantity per Package: 1
• UPC: 030999309686

Fitment

Fits Evinrude outboard prop and driveshaft applications that use the OMC 303345 oil seal.

Replaces (OEM)

• OMC 303345

Frequently Asked Questions

What does the Sierra 18-2022 oil seal fit? The Sierra 18-2022 is designed for Evinrude outboard prop and driveshaft applications that originally used the OMC 303345 oil seal.

Is the 18-2022 seal equivalent to an OMC part? Yes, the Sierra 18-2022 replaces OMC part number 303345 and is built as a direct functional equivalent for that position.

What are the dimensions of this oil seal? The Sierra 18-2022 oil seal measures 0.39 x 0.39 x 0.39 inches.

How much does the 18-2022 oil seal weigh? This seal weighs 0.02 pounds.

How is the 18-2022 oil seal installed? Installation is bolt-on, meaning the seal presses or bolts into place in the gearcase without requiring modification to surrounding components.

How many seals come in one package? One Sierra 18-2022 oil seal is included per package, matching a one-per-position replacement need.

When should I replace the 18-2022 oil seal? This seal should be replaced when water intrusion, oil seepage, or gearcase leaks are noticed, or during a scheduled lower unit or gearcase service.

What is the UPC for the Sierra 18-2022 oil seal? The UPC for the Sierra 18-2022 oil seal is 030999309686.

Is the Sierra 18-2022 a genuine OMC part or aftermarket? The Sierra 18-2022 is a Sierra-branded aftermarket seal manufactured to replace the OMC 303345 oil seal, not an OMC-branded original part.

What category of Evinrude parts does the 18-2022 belong to? It is listed under Evinrude outboard prop and driveshaft seals, reflecting its use at the driveshaft/prop seal position on Evinrude outboards.