Sierra Oil Seal 18-2028, Replaces OMC 321480, for Evinrude Outboard Prop and Driveshaft

The Sierra 18-2028 Oil Seal is a replacement oil seal engineered for Evinrude outboard prop and driveshaft applications. It is designed as a direct equivalent to OMC part number 321480, giving boat owners and technicians a reliable way to restore a proper seal without sourcing increasingly hard-to-find original equipment parts. The seal has a machined exterior finish for a precise, consistent fit against the mating surfaces it seals.

This is a compact, lightweight component at just 0.02 pounds, sized to fit into the prop and driveshaft seal area of the outboard lower unit. Keeping this seal in good condition helps prevent water intrusion and lubricant loss around the driveshaft and propeller shaft, both of which can lead to gear case damage if left unaddressed. Because it is a direct OEM cross-reference part, it installs the same way the original 321480 seal did, using standard hand tools and typical lower-unit service procedures.

The 18-2028 is intended for outboard owners performing routine lower unit maintenance, seal replacement during a gear case rebuild, or repair work after a water intrusion issue is diagnosed. It is manufactured in China and shipped as a single seal.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2028
• Product Type: Oil Seal
• OEM Cross Reference: 321480
• Finish: Machined
• Weight: 0.02 pounds
• Package Dimensions: 0.508 H x 4.572 L x 3.302 W (centimeters)
• Country of Origin: China
• Application: Evinrude outboard prop and driveshaft seal
• UPC: 030999309747

Fitment

• Evinrude outboard prop and driveshaft seal application

Replaces (OEM)

• OMC 321480

Frequently Asked Questions

What does the Sierra 18-2028 oil seal replace? The Sierra 18-2028 is a direct cross-reference to OMC part number 321480, so it can be used anywhere that original seal was specified.

What is the Sierra 18-2028 used for? It is an oil seal used in the prop and driveshaft area of Evinrude outboard lower units, sealing against water intrusion and lubricant loss.

How much does the 18-2028 oil seal weigh? It weighs 0.02 pounds, making it a small, lightweight lower-unit seal.

Is the 18-2028 a genuine Sierra part or aftermarket? The 18-2028 is a Sierra-branded replacement part manufactured to cross-reference OMC 321480, sold as a Sierra aftermarket equivalent rather than an OMC-branded original.

What finish does the 18-2028 seal have? This oil seal has a machined exterior finish for a precise fit at the sealing surface.

Where is the Sierra 18-2028 oil seal manufactured? The 18-2028 oil seal is manufactured in China.

Does the 18-2028 come as a single seal or a set? The Sierra 18-2028 is supplied as a single oil seal, not a multi-piece kit.

What are the package dimensions of the 18-2028 seal? The Sierra 18-2028 ships in packaging measuring 0.508 cm high by 4.572 cm long by 3.302 cm wide.

Will the 18-2028 fit any outboard other than Evinrude? The Sierra 18-2028 is listed under Evinrude outboard prop and driveshaft seal applications; fitment outside that application is not specified.

How do I know I need to replace this oil seal? Signs like water in the lower unit lubricant or lubricant leaking from the driveshaft or prop shaft area typically indicate the oil seal, such as the Sierra 18-2028, needs replacement.

Does the Sierra 18-2028 include installation hardware? No, the 18-2028 is the oil seal itself; no additional hardware is included in the package.