Sierra 18-2791 Lower Unit Seal Kit - Replaces OMC 3850597

The Sierra 18-2791 Lower Unit Seal Kit provides the seals needed to service and reseal a marine outboard or sterndrive lower unit, helping prevent gear lube leaks and water intrusion into the gearcase. It is supplied as a complete kit so the necessary seals are on hand in a single part number rather than sourcing individual pieces separately. The kit is packaged as a single unit (Number of Items: 1) and is sold per piece. Country of origin is Taiwan, and the kit carries a limited warranty from Sierra.

This kit is a direct cross-reference to OEM part 3850597, making it straightforward to identify as the correct replacement when servicing a lower unit originally fitted with that OEM seal. Buyers replacing worn or hardened lower unit seals during a gearcase rebuild, prop shaft seal replacement, or routine maintenance can use this kit to restore a proper seal without needing to locate discontinued or harder-to-find original equipment parts.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2791
• Replaces (OEM): 3850597
• UPC: 808282113049
• Weight: 0.27 pounds
• Package Dimensions: 10.88 x 8 x 1.75 inches
• Item Dimensions: 8 x 1.75 x 10.87 inches
• Color: White
• Country of Origin: Taiwan
• Number of Items: 1

Fitment

Designed as a lower unit seal kit for marine outboard/sterndrive applications originally using OEM seal 3850597.

Replaces (OEM)

• 3850597

Frequently Asked Questions

What does the Sierra 18-2791 Lower Unit Seal Kit include? The 18-2791 kit includes the seals needed to reseal a marine lower unit, packaged as a single kit (Number of Items: 1) rather than individual loose seals.

What OEM part number does the 18-2791 kit replace? Sierra 18-2791 replaces OEM part 3850597, so it can be ordered as a direct substitute wherever that original seal is called for.

Is the 18-2791 kit genuine Sierra or an aftermarket part? It is a genuine Sierra-branded part, sold under Sierra part number 18-2791, and functions as an aftermarket equivalent to the original OEM 3850597 seal.

How much does the 18-2791 Lower Unit Seal Kit weigh? The kit weighs 0.27 pounds.

What are the package dimensions of the 18-2791 seal kit? Packaged dimensions for the Sierra 18-2791 kit are 10.88 x 8 x 1.75 inches, with item dimensions of 8 x 1.75 x 10.87 inches.

Where is the Sierra 18-2791 seal kit manufactured? This kit's country of origin is Taiwan.

What color are the components in the 18-2791 kit? The kit is listed in white.

Does the 18-2791 kit come with a warranty? Yes, the Sierra 18-2791 Lower Unit Seal Kit is covered by a limited warranty.

How many seal kits come in one 18-2791 package? One 18-2791 kit contains a single unit (Number of Items: 1), and it is priced and sold per piece.

When would I need the 18-2791 Lower Unit Seal Kit? This kit is used when servicing or rebuilding a lower unit gearcase that originally used seal 3850597, such as during a reseal to stop gear lube leaks.

Is Sierra 18-2791 the correct part number to search for this seal kit? Yes, 18-2791 is the public Sierra part number for this Lower Unit Seal Kit and is the number to reference when ordering or cross-checking against OEM 3850597.