396351 Gearcase Seal Kit for Evinrude Johnson | JLM Marine

Gearcase Seal Kit for Evinrude Johnson Outboards – OEM 396351 Replacement

This aftermarket gearcase seal kit is engineered to fit Evinrude and Johnson 2-stroke outboards ranging from 20 HP to 35 HP, covering model years 1976 through 2005. It provides a complete seal replacement solution for lower unit maintenance and repair, ensuring reliable protection against water intrusion and gear oil leaks.

This kit directly replaces OEM part numbers 396351, 0396351, and aftermarket equivalents including 18-2658 and 18-8387. It is designed to meet OEM specifications for form, fit, and function, offering dependable performance for your lower unit service needs.

• Complete seal kit for lower unit gearcase applications
• Fits multiple horsepower ratings across two decades of production
• Aftermarket replacement manufactured to OEM standards

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 Serial Number Guide.

Technical Specifications

Package Contents

This gearcase seal kit includes:

• 1 × Complete Gearcase Seal Kit

The package contains all the seals and components shown in the product images.

Installation Guide

1. Disconnect the spark plug wire and place the outboard in a stable, upright position. Drain all gear oil from the lower unit into an appropriate container.
2. Remove the propeller, then disconnect the shift linkage at the lower unit. Unbolt and separate the lower unit from the midsection.
3. Disassemble the lower unit housing to access the drive shaft, propeller shaft, and bearings. Remove old seals carefully to avoid damaging seal surfaces.
4. Clean all seal surfaces, bearing races, and housing bores thoroughly with a suitable solvent. Inspect for wear, corrosion, or damage; replace bearings if necessary.
5. Lubricate new seals lightly with gear oil. Install seals using the correct drivers or installation tools, ensuring they are seated squarely and to the proper depth.
6. Reassemble the lower unit components in reverse order, ensuring all snap rings, washers, and shims are correctly positioned. Apply marine-grade sealant to mating surfaces as specified.
7. Reattach the lower unit to the midsection and torque all fasteners to manufacturer specifications. Reconnect the shift linkage and verify smooth operation through all gears.
8. Refill the lower unit with the recommended type and quantity of gear oil. Check for leaks and proper oil level at both fill and vent screws.
9. Reinstall the propeller and torque the propeller nut to specification. Reconnect the spark plug wire and perform a water test to confirm proper sealing and operation.

Troubleshooting & FAQ

Q: How do I confirm this seal kit fits my engine?
A: Cross-reference your outboard's horsepower, model year, and OEM part number with the compatibility table above. If your engine falls within the listed HP ranges (20–35 HP, 2-stroke) and years (1976–2005), this kit should fit. Always compare the seal kit contents with your exploded parts diagram to verify.

Q: How often should I replace the gearcase seals?
A: Replace gearcase seals whenever you notice milky or contaminated gear oil, evidence of water intrusion, or during lower unit overhaul. Many technicians recommend inspecting seals every 2–3 years or 200–300 operating hours, and replacing them proactively during bearing or impeller service.

Q: What are the signs of failing lower unit seals?
A: Common symptoms include milky or frothy gear oil (indicating water intrusion), oil leaking from the lower unit, unusual noise or vibration from the gearcase, or difficulty shifting. Any of these signs warrant immediate inspection and seal replacement.

Q: Can I reuse the old seals if they look okay?
A: No. Seals are designed for single use; removing them typically distorts the sealing lip. Always install new seals during any lower unit service to ensure reliable performance and prevent costly water damage or gear failure.

Q: Is this an OEM or aftermarket part?
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.