Sierra 18-2673 Upper Unit Seal Kit, Replaces 984459 986364 987603, for All Cobra (1986-89) OMC Sterndrive

The Sierra 18-2673 Upper Unit Seal Kit is a seal set engineered for the upper gearcase unit on All Cobra (1986-89) OMC sterndrive applications. It is built to replace the OEM upper unit seals that wear out over time from heat, vibration, and constant exposure to water and gear lubricant, restoring a proper seal against water intrusion and lubricant loss in the upper drive unit. This kit is a direct cross-reference for OMC OEM part numbers 984459, 986364, and 987603, so it installs as a like-for-like replacement without modification to the drive unit.

This is a seal kit specifically for the upper unit of the sterndrive, distinct from the companion 18-2674 Transom Mount Seal Kit, which is a separate part number covering a different section of the drive. Ordering the correct kit for the section of the drive being serviced ensures the right seals are on hand for the job. The kit weighs 0.24 pounds as packaged.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2673
• Product Name: Upper Unit Seal Kit
• Category: OMC Bellows and Transom Seal
• Weight: 0.24 pounds
• UPC: 808282258023
• Replaces (OEM): 984459, 986364, 987603
• Fitment: All Cobra (1986-89)

Fitment

• All Cobra (1986-89) OMC Sterndrive

Replaces (OEM)

• 984459
• 986364
• 987603

Frequently Asked Questions

What does the Sierra 18-2673 Upper Unit Seal Kit fit? The Sierra 18-2673 Upper Unit Seal Kit fits All Cobra (1986-89) OMC sterndrive applications.

Which OEM part numbers does the 18-2673 replace? Sierra 18-2673 replaces OMC OEM part numbers 984459, 986364, and 987603.

How much does the 18-2673 seal kit weigh? The Sierra 18-2673 Upper Unit Seal Kit weighs 0.24 pounds.

Is the 18-2673 kit the same as the 18-2674 kit? No, 18-2673 is the Upper Unit Seal Kit while 18-2674 is the Transom Mount Seal Kit, a separate part number for a different section of the same Cobra sterndrive application.

Will this kit work on any OMC sterndrive? The 18-2673 kit is designated for All Cobra (1986-89) applications; it is not listed as fitting other OMC sterndrive models.

Is Sierra 18-2673 a genuine OEM part or aftermarket? Sierra 18-2673 is a Sierra-branded replacement part manufactured as a cross-reference equivalent to OMC OEM numbers 984459, 986364, and 987603.

What section of the drive does the 18-2673 kit service? The 18-2673 kit contains seals for the upper unit (upper gearcase) of the Cobra sterndrive, as opposed to the transom mount section covered by 18-2674.

Why would I need to replace these seals? Upper unit seals in the Cobra sterndrive wear from heat, vibration, and constant exposure to water and gear lubricant, and the 18-2673 kit provides the replacement seals needed to restore a proper seal.

Can I order 18-2673 by its UPC code? Yes, the Sierra 18-2673 Upper Unit Seal Kit carries UPC 808282258023.

Does the 18-2673 kit include installation instructions? The dossier for the 18-2673 Upper Unit Seal Kit does not specify included instructions; it is sold as the seal kit itself.