Sierra Oil Seal 18-2073, Replaces OMC 981268, Evinrude Outboard Prop and Driveshaft Seal

The Sierra 18-2073 is an oil seal engineered for Evinrude outboard prop and driveshaft applications. It is designed as a direct equivalent for OMC part number 981268, restoring a proper seal where the driveshaft or propeller shaft passes through the gearcase housing to keep gear lubricant in and water out. A compromised or worn seal in this location is a common cause of milky gear oil and water intrusion into the lower unit, so replacing this seal is a routine part of gearcase maintenance and rebuild work.

This seal measures 0.39 x 0.39 x 0.39 inches and weighs 0.07 pounds, with a machined exterior finish for a precise fit against the housing bore and shaft. Because oil seals are wear items exposed to constant shaft rotation, heat, and lubricant contact, they should be replaced any time a gearcase is opened up for service rather than reused. This part is sold individually; some gearcase applications call for multiple units of this seal, so confirm the quantity needed for your specific rebuild before ordering.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2073
• Product Name: Oil Seal
• Category: Evinrude Outboard Prop & Driveshaft Seals
• Dimensions: 0.39 x 0.39 x 0.39 inches
• Weight: 0.07 pounds
• Exterior Finish: Machined
• UPC: 030999310248
• OEM Cross-Reference: 981268

Fitment

Used in Evinrude outboard prop and driveshaft assemblies that call for OEM seal 981268.

Replaces (OEM)

• 981268

Frequently Asked Questions

What does the Sierra 18-2073 oil seal replace? It replaces OEM part number 981268, so it can be ordered as a direct equivalent for that seal in Evinrude outboard prop and driveshaft applications.

What are the dimensions of this oil seal? The Sierra 18-2073 measures 0.39 x 0.39 x 0.39 inches, sized to seat precisely in the gearcase bore against the shaft.

How much does the 18-2073 oil seal weigh? It weighs 0.07 pounds.

What is this seal used for? This seal is used in Evinrude outboard prop and driveshaft assemblies to keep gear lubricant contained and water out of the lower unit where the shaft passes through the housing.

Is the 18-2073 a genuine Evinrude/OMC part or an aftermarket replacement? The Sierra 18-2073 is an aftermarket seal manufactured by Sierra as an equivalent to OMC part 981268, not an OMC-branded original part.

What finish does the 18-2073 seal have? It has a machined exterior finish for a precise fit within the gearcase housing bore.

How many of these seals do I need for a gearcase rebuild? The Sierra 18-2073 is sold individually; check your specific gearcase parts breakdown, since some rebuilds call for more than one of this seal.

Should I reuse an old oil seal instead of replacing it? No, an oil seal like the 18-2073 is a wear item and should be replaced any time the gearcase is opened, since a worn seal allows water intrusion or lubricant loss.

What signs indicate this oil seal needs replacement? Milky or discolored gear lubricant and water found in the lower unit are common signs that the seal at this location, such as the Sierra 18-2073, has failed and needs replacement.

What is the part number to reference when ordering? Reference Sierra part number 18-2073, or its OEM equivalent 981268, when ordering this seal.