Sierra 18-2646-1 Lower Unit Seal Kit for Alpha One Gen II Sterndrives

The Sierra 18-2646-1 Lower Unit Seal Kit is a complete, single-package seal kit engineered for Alpha One Gen II sterndrives, including the Alpha One Gen II (CR) variant. It is built to reseal the lower unit during a gearcase rebuild or when addressing gear lube leaks, restoring a proper seal against water intrusion and lubricant loss. The kit ships as one count per package, so the full set of lower unit seals needed for the job is included together rather than sold as loose individual seals. Components in the kit are round in shape with a white finish. Sierra backs this kit, like all Sierra parts, with its customer satisfaction warranty.

This kit is specific to the Alpha One Gen II family and covers a broad span of production serial numbers, from early 1991-1995 units through 1998-2010 units. It is not the correct kit for the earlier Alpha One SS or for Bravo I/Bravo II sterndrives, which use different Sierra kit numbers.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2646-1
• Product Type: Lower Unit Seal Kit
• Fitment: Alpha One Gen II and Alpha One Gen II (CR) sterndrives
• Unit Count: 1 kit per package
• Color: White
• Shape: Round
• Weight: 0.23 pounds
• UPC: 808282258016

Fitment

• Alpha One Gen II, 1991-1995, serial number D469859 through F679999
• Alpha One Gen II (CR), 1991-1995, serial number D469859 through F679999
• Alpha One Gen II, 1996-1997, serial number F680000 through K999999
• Alpha One Gen II (CR), 1996-2010, serial number F680000 and up
• Alpha One Gen II, 1998-2010, serial number L100040 and up

Frequently Asked Questions

What does the Sierra 18-2646-1 Lower Unit Seal Kit include? The Sierra 18-2646-1 is packaged as a single complete lower unit seal kit, one kit per package, rather than as individual loose seals.

Which sterndrives does Sierra 18-2646-1 fit? Sierra 18-2646-1 fits Alpha One Gen II and Alpha One Gen II (CR) sterndrives, covering serial ranges from D469859 through L100040 and up.

Does 18-2646-1 fit the Alpha One SS? No. The Alpha One SS (1986-1989) uses a different Sierra seal kit, 18-2652, so the Sierra 18-2646-1 kit is not the correct part for that drive.

Will 18-2646-1 fit a Bravo I or Bravo II sterndrive? No, Bravo I and Bravo II sterndrives use a different Sierra kit, 18-2645, not the 18-2646-1 kit which is built specifically for Alpha One Gen II drives.

What serial number range does 18-2646-1 cover on early Alpha One Gen II units? For 1991-1995 Alpha One Gen II and Alpha One Gen II (CR) drives, the Sierra 18-2646-1 kit covers serial number D469859 through F679999.

Is a different kit needed for later Alpha One Gen II sterndrives? No, the same Sierra 18-2646-1 kit also covers 1996-1997 units (serial F680000 through K999999), 1996-2010 CR units (serial F680000 and up), and 1998-2010 units (serial L100040 and up).

How much does the Sierra 18-2646-1 seal kit weigh? The Sierra 18-2646-1 Lower Unit Seal Kit weighs 0.23 pounds.

Is Sierra 18-2646-1 a genuine Sierra part with a warranty? Yes, the 18-2646-1 kit is a genuine Sierra part and, like all Sierra parts, is covered under Sierra's customer satisfaction warranty.

What color and shape are the components in kit 18-2646-1? The seal components in the Sierra 18-2646-1 kit are round and finished in white.

How many of these kits come in a package? Sierra 18-2646-1 ships as a single unit, one complete seal kit per package.

Does 18-2646-1 cover both the standard and CR versions of the Alpha One Gen II? Yes, the Sierra 18-2646-1 kit is listed for both the standard Alpha One Gen II and the Alpha One Gen II (CR) across the covered serial ranges.