Sierra Lower Unit Seal Kit 18-2672, Replaces OMC 439967/984458/985613, for V6/V8 Cobra Stern Drive (1986-1991)

The Sierra 18-2672 Lower Unit Seal Kit is a complete set of replacement seals for the lower unit of OMC V6/V8 Cobra stern drives from the 1986-1991 model years. It is built to restore the watertight, oil-tight seal between the lower unit housing and internal shift components, a common maintenance point when a drive shows signs of gear lube seepage, water intrusion, or shift linkage wear at the lower unit interface. The kit is a direct cross-reference for OMC part numbers 439967, 984458, and 985613, so it fits in place of the original equipment components without modification.

Inside the kit you get a shift cover gasket, two grommets, and a wiper, each matched to its corresponding OMC original equipment number so a technician or DIY boater can complete a full lower unit reseal in one job rather than sourcing individual seals separately. The kit is compatible with OMC Cobra stern drive models SF-20, SF-25, SF-30, SF-35, SF-42, SF-20F, SF-25F, SF-30F, SF-35F, and SF-42F. At 0.19 pounds, it ships as a compact small-parts kit intended for use during routine lower unit service or gear lube changes on applicable Cobra stern drives.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2672
• Product Name: Lower Unit Seal Kit
• Fitment: All V6/V8 Cobra (1986-1991)
• Compatible Models: SF-20, SF-25, SF-30, SF-35, SF-42, SF-20F, SF-25F, SF-30F, SF-35F, SF-42F
• Kit Contents: Shift Cover Gasket (OEM 911878, Qty 1), Grommet (OEM 911705, Qty 2), Wiper (OEM 912157, Qty 1)
• Weight: 0.19 pounds
• Color: White
• UPC: 030999312839

Fitment

• All V6/V8 Cobra (1986-1991)

Replaces (OEM)

• 439967
• 984458
• 985613

Frequently Asked Questions

What does the Sierra 18-2672 lower unit seal kit fit? The 18-2672 kit is built for all V6/V8 Cobra stern drives from the 1986-1991 model years, including the SF-20, SF-25, SF-30, SF-35, SF-42, SF-20F, SF-25F, SF-30F, SF-35F, and SF-42F models.

Which OEM part numbers does 18-2672 replace? Sierra 18-2672 cross-references to OMC part numbers 439967, 984458, and 985613, so it installs in place of any of those original equipment numbers.

What is included in the 18-2672 seal kit? The kit contains one shift cover gasket (OEM 911878), two grommets (OEM 911705), and one wiper (OEM 912157), covering the seal points typically serviced together on a Cobra lower unit.

How much does the 18-2672 lower unit seal kit weigh? The Sierra 18-2672 kit weighs 0.19 pounds.

What color are the components in the 18-2672 kit? The seal kit components in Sierra 18-2672 are white.

Is Sierra 18-2672 a genuine OMC part or an aftermarket replacement? 18-2672 is a Sierra-manufactured replacement kit, not an original OMC part, but it is a direct equivalent to OMC 439967, 984458, and 985613 and is designed to fit the same applications.

Does 18-2672 fit 4-cylinder Cobra drives? No, the 18-2672 kit is designated for V6/V8 Cobra stern drives (1986-1991); a 4-cylinder Cobra seal kit is a separate part number.

Can I use 18-2672 to fix gear lube leaks at the lower unit? Yes, the shift cover gasket, grommets, and wiper in the Sierra 18-2672 kit are the seal points commonly responsible for gear lube seepage at the lower unit on applicable V6/V8 Cobra drives.

How many grommets come in the Sierra 18-2672 kit? Two grommets (OEM 911705) are included in the 18-2672 lower unit seal kit.

Is professional installation required for the 18-2672 seal kit? The kit supplies the gasket, grommets, and wiper for a lower unit reseal on V6/V8 Cobra stern drives; installation follows standard lower unit disassembly and is commonly performed by a marine technician or an experienced DIY boater.