Gearcase Seal Kit – Fits Johnson/Evinrude 20-35 HP (Replaces 396351, 18-2658)

Gearcase Seal Kit – Fits Johnson/Evinrude 20-35 HP (Replaces 396351, 18-2658)

This gearcase seal kit is designed for Johnson/Evinrude 2-Stroke outboard motors from 20 HP to 35 HP, covering models manufactured between 1977 and 2005. It provides the essential components needed to rebuild your lower unit and prevent water from entering the gearcase.

This kit is a direct replacement for multiple OEM and aftermarket part numbers, ensuring wide compatibility. It is engineered to meet or exceed original equipment specifications for a reliable, long-lasting seal.

• Complete Kit: Includes all necessary oil seals, O-rings, gaskets, and washers for a full lower unit service.
• Function: Effectively prevents water intrusion and maintains gear oil inside the gearcase, protecting vital components from corrosion and wear.
• Materials: Constructed from high-quality, corrosion-resistant rubber and plastic materials suitable for harsh marine environments.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Johnson/Evinrude owners, here’s a guide to help you identify your engine’s serial/model: Johnson/Evinrude Serial Number Guide.

Technical Specifications

Package Contents

• 1 x Impeller Plate Gasket
• 1 x Set of Oil Seals
• 1 x Rubber Seal
• 1 x Washer
• 1 x Set of O-Rings

Installation Guide

This gearcase seal kit is intended for owners with mechanical experience. It should be used when rebuilding or servicing the lower unit of your outboard.

1. Inspect Your Gear Oil: The primary sign that your seals have failed is milky or cloudy gear oil. This indicates water has contaminated the oil, and the seals must be replaced.
2. Prepare for Service: Safely secure the outboard motor and drain the old gear oil completely from the lower unit.
3. Disassemble Lower Unit: Carefully disassemble the gearcase according to your manufacturer's service manual to access the old seals.
4. Install New Seals: Remove the old seals, gaskets, and O-rings. Clean the housing surfaces thoroughly and install the new components from the kit.
5. Reassemble and Refill: Reassemble the gearcase, ensuring all parts are correctly seated. Refill with fresh, high-quality marine gear oil to the proper level.

Troubleshooting & FAQ

Q: How do I know if this seal kit will fit my engine?

A: This kit fits most Johnson/Evinrude 2-stroke outboards from 20 to 35 HP manufactured between 1977 and 2005. To ensure a perfect match, please check your engine model and year against the "Compatible Engine Models" table on this page. We strongly recommend cross-referencing your existing part number with the provided list (OEM 396351, Sierra 18-2658, etc.).

Q: What are the signs that my gearcase seals need to be replaced?

A: The most common sign of a failed gearcase seal is finding milky, white, or cloudy gear oil when you check or drain it. This indicates that water has breached the seals and is mixing with the oil. Continuing to run the engine in this condition can cause severe damage to the gears and bearings.

Q: Is this kit difficult to install?

A: Installation requires disassembling the lower unit (gearcase). While it is a straightforward process for those with mechanical experience and the right tools, we recommend professional installation if you are not familiar with outboard motor repair. Always refer to a service manual for your specific engine model.

Q: OEM vs. Aftermarket?

A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?

A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?

A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.