Gearcase Seal Kit – Fits Johnson/Evinrude/OMC Outboards (Replaces 985612)

$35.74

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Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This Gearcase Seal Kit is designed for Johnson/Evinrude/OMC outboards, specifically for various stern drive models equipped with the 2.5L 4-cylinder engines from 1986. It provides the necessary components to service and reseal the lower gearcase unit, preventing water intrusion and oil leaks.

It serves as a direct replacement for Johnson/Evinrude part number 985612 / 0985612, OMC 984457 / 0984457, and Sierra aftermarket part 18-2671.

Installation Method: Direct replacement
Application Area: Lower gearcase
Contents: Includes essential seals and O-rings for service

Part Number Matrix

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

Brand	Part Number	Notes
Johnson/Evinrude	985612 / 0985612
OMC	984457 / 0984457	Superseded by 985612
Sierra	18-2671	Aftermarket cross-reference

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For OMC applications, this kit is specified for the 1986 2.5L stern drive models.

Brand	Model	Rated HP	Years	OEM Part No.	Notes
OMC	Stern Drive 2.5L	252APKWB	1986	985612	Replaces 0984457

Technical Specs

Product Type: Gearcase Seal Kit
Installation: Direct replacement
Dimensions: 18.0" L x 12.0" W x 2.5" H
Other Technical Attributes: Used in lower gearcase

What’s in the Box

Multiple seals for gearcase service
Assorted O-rings for a complete fit

Installation Notes

Safely secure the outboard and drain the gearcase lubricant completely into a suitable container.
Remove the propeller, followed by the gearcase housing bolts, and carefully detach the lower unit.
Systematically remove the old seals, O-rings, and gaskets, paying close attention to their original orientation.
Thoroughly clean all mating surfaces and seal cavities, ensuring they are free of old sealant, corrosion, and debris.
Lightly lubricate the new seals and O-rings with marine grease before carefully pressing them into place.
Reassemble the gearcase, ensuring all components are aligned correctly, and torque bolts to manufacturer specifications.
Refill the gearcase with the recommended type and amount of fresh lubricant before returning to service.

Troubleshooting & FAQ

How do I confirm this kit fits my specific engine model?

This kit is specifically listed for the 1986 OMC Stern Drive 2.5L engine (model 252APKWB). Always cross-reference the OEM part number (985612) with your engine's service manual or parts diagram to ensure an exact match before ordering.

What are the signs of a failing gearcase seal?

The most common indicators of a failed seal are milky, water-contaminated gear lube upon draining, visible oil slicks on the water around your lower unit, or oil leaking from the propeller shaft area. Any of these signs suggest it's time for a reseal.

Is this a complete kit for the entire lower unit?

This kit includes the primary seals and O-rings required for a standard lower gearcase service as referenced by the OEM part number. However, depending on the condition of your unit, other specific gaskets or bearings may be needed. Always inspect your components during disassembly.

How does this aftermarket kit compare to the original OMC part?

Our kit is engineered to meet or exceed original equipment manufacturer (OEM) specifications for fit, material durability, and sealing performance. It provides a reliable, long-lasting repair at a more accessible price point.

What is the recommended replacement interval for gearcase seals?

There is no fixed interval, but seals should be inspected annually when you change your gear lube. It is good practice to replace them if you notice any signs of leakage, if the engine has overheated, or every 3-5 years as preventative maintenance, especially in saltwater environments.

Can I install this kit myself?

While DIY installation is possible for those with mechanical experience and the correct tools, we recommend professional installation to ensure all seals are seated correctly without damage, preventing premature failure and ensuring optimal performance.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

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.

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