Seal Kit Upper Unit – Fits OMC Stringer Unit (Replaces OMC 981799)

Product Details

This Seal Kit Upper Unit – Fits OMC Stringer Unit (Replaces OMC 981799) is engineered for OMC Stringer sterndrives, specifically models 100-245 produced between 1968 and 1972 that feature pressed-on ball gears. It provides the essential seals and o-rings for upper unit maintenance.

It serves as a direct replacement for Sierra 18-2666 and GLM 87651, offering a reliable alternative to the original OMC part 981799.

• Installs in the upper unit of the sterndrive.
• Designed exclusively for units with pressed-on ball gears.
• Will not fit units where ball gears are secured by nuts.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

This kit is designed for a wide range of vintage OMC Stern Drive models.

Technical Specs

Product Type

Seal Kit

Installation

Upper Unit

Dimensions

11.0" H x 13.0" W x 4.0" L

Weight

0.36 kg (0.8 lbs)

Other Technical Attributes

For units with pressed-on ball gears; will not fit units with ball gears held on by nuts.

What’s in the Box

• Upper Gearcase Gasket (18-0939/315189)
• Oil Seal (18-2073/981268)
• Rubber Seal (18-3111/907774)
• Washer (18-4248/311598)
• O-Ring (18-7103/308624)
• O-Ring (18-7107/313175)
• O-Ring (18-7121/308621)
• O-Ring (18-7134/303059)
• O-Ring (18-7146/554545)
• O-Ring (18-7158/310585/310967)
• O-Ring (18-7172/553126)
• O-Ring (18-7173/910582)
• O-Ring (18-7198/308626)

Installation Notes

1. Disconnect the battery cables and ensure the engine is switched off and cool to the touch.
2. Position a drain pan under the sterndrive and remove the upper and lower drain/fill plugs to drain the gearcase lubricant.
3. Carefully disassemble the upper unit components to gain access to the seals and o-rings that need replacement.
4. Remove the old seals, gaskets, and o-rings. Pay close attention to avoid scratching or damaging the housing or mating surfaces.
5. Thoroughly clean all sealing surfaces to remove any old sealant, corrosion, or debris. A clean surface is crucial for a proper seal.
6. Lightly lubricate the new seals and o-rings with marine grease before installation to ensure smooth seating and prevent damage.
7. Carefully install the new components from the kit, ensuring each part is seated correctly in its designated groove or position.
8. Reassemble the upper unit, torquing all fasteners to the manufacturer's specifications.
9. Refill the gearcase with the recommended type and amount of sterndrive lubricant.
10. After refilling, check for any signs of leaks around the seals before launching the boat.

Troubleshooting & FAQ

Safety & Important Info

• Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
• This is an aftermarket replacement, not an OEM component.
• Professional installation is recommended for safety and performance.

About Sea Sierra

• Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
• Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
• Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.