Sierra 18-2011 Oil Seal for MerCruiser 60/80/90 Gear Housing (1965-1972), Replaces Mercury Marine 26-90562

The Sierra 18-2011 is a lower gear housing oil seal built for MerCruiser 60/80/90 model stern drives produced from 1965 to 1972. It is a precision-machined replacement seal used during gear housing service, sealing the housing against water intrusion and lubricant loss at the shaft. The seal cross-references directly to Mercury Marine part number 26-90562, making it a straightforward drop-in replacement for boaters and marine technicians rebuilding or servicing the lower unit on this model line.

The 18-2011 measures 1.250 inches in outer diameter, has a shaft size of 0.750 inches, and a width of 0.312 inches, with a machined exterior finish. It is a compact, lightweight component at 0.02 pounds, sized to fit within the gear housing seal carrier alongside the other components (such as the O-ring and bearing carrier) used in MerCruiser 60/80/90 gear housing seal service.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2011
• Category: MerCruiser Lower Gear Housing Seal
• Outer Diameter: 1.250 inches
• Shaft Size: 0.750 inches
• Width: 0.312 inches
• Product Dimensions: 0.39 x 0.39 x 0.39 inches
• Weight: 0.02 pounds
• Exterior Finish: Machined
• UPC: 030999309570

Fitment

• MerCruiser 60 / 80 / 90 model gear housings, 1965-1972

Replaces (OEM)

• Mercury Marine 26-90562

Frequently Asked Questions

What does the Sierra 18-2011 oil seal fit? The 18-2011 is designed for MerCruiser 60/80/90 model lower gear housings built from 1965 to 1972.

Is the Sierra 18-2011 the same as Mercury Marine 26-90562? Yes, the 18-2011 cross-references directly to Mercury Marine part number 26-90562.

What are the dimensions of this seal? The 18-2011 measures 1.250 inches in outer diameter, 0.750 inch shaft size, and 0.312 inch width.

How much does the 18-2011 oil seal weigh? 0.02 pounds.

What is the exterior finish on this seal? The Sierra 18-2011 has a machined exterior finish.

Is this a genuine Mercury OEM part or an aftermarket replacement? The 18-2011 is manufactured by Sierra as an aftermarket seal engineered to the Mercury Marine 26-90562 specification, rather than a Mercury-branded part.

What is the UPC for the Sierra 18-2011? 030999309570.

Where does this seal fit within the gear housing? In the MerCruiser 60/80/90 gear housing seal chart, the 18-2011 is listed as the Seal component alongside the O-ring and bearing carrier used for that model and year range.

Does the 18-2011 fit later MerCruiser models like the Alpha One? No, the 18-2011 is listed specifically for the 60/80/90 model gear housings covering 1965-1972; later MerCruiser drive lines use different Sierra seal part numbers.

What size shaft does the 18-2011 seal accept? A 0.750 inch shaft, per the seal's listed shaft size.

What is included with this part? The 18-2011 is sold as a single oil seal, not a full gear housing seal kit.

Can the 18-2011 be cross-referenced by its Mercury Marine number? Yes, searching Mercury Marine 26-90562 will return the Sierra 18-2011 as its cross-referenced equivalent.