Gearcase Seal Kit – Fits Johnson/Evinrude 20-35 HP Outboards (Replaces 396351, 777559)
Gearcase Seal Kit – Fits Johnson/Evinrude 20-35 HP Outboards (Replaces 396351, 777559) is backordered and will ship as soon as it is back in stock.
Couldn't load pickup availability
Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Gearcase Seal Kit – Fits Johnson/Evinrude 20-35 HP Outboards (Repla...
Product Details
This Gearcase Seal Kit – Fits Johnson/Evinrude 20-35 HP Outboards (Replaces 396351, 777559) is an essential aftermarket component for servicing the lower unit of 2-stroke outboard motors, specifically designed for Johnson/Evinrude 20–25 HP (1985–2005) and 30–35 HP (1977–2005) models. It provides the necessary seals to prevent water intrusion and lubricant leaks, ensuring gearcase longevity.
This kit serves as a direct interchange for Johnson/Evinrude part numbers 0396351, 396351, 0777559, and 777559, as well as aftermarket references Sierra 18-2658, GLM 87680, and Mallory 9-74101.
- Includes a comprehensive set of seals, o-rings, and hardware for a complete gearcase rebuild.
- Engineered from high-quality, corrosion-resistant materials for durability in harsh marine environments.
- Designed for manual installation in the gearcase/lower unit by a qualified marine mechanic.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Johnson/Evinrude | 0396351 |
| Johnson/Evinrude | 396351 |
| Johnson/Evinrude | 0777559 |
| Johnson/Evinrude | 777559 |
| Sierra | 18-2658 |
| GLM | 87680 |
| Mallory | 9-74101 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Johnson/Evinrude | Outboards | 20–25 | 2-Stroke | 1985–2005 | 396351, 777559 |
| Johnson/Evinrude | Outboards | 30–35 | 2-Stroke | 1977–2005 | 396351, 777559 |
Technical Specs
- Product Type
- Lower Unit Gearcase Seal Kit
- Installation
- Manual installation in gearcase/lower unit
- Fuel Type
- Compatible with gasoline engines
- Housing Material
- Metal, plastic, rubber components
- Dimensions
- 12.0″ L × 10.0″ W × 4.0″ H (305 × 254 × 102 mm)
- Weight
- 0.139 kg (4.9 ounces)
- Other Technical Attributes
- Made of high-quality materials for durability in harsh marine environments
- Warranty
- 30-day return policy (varies by retailer)
What’s in the Box
- 1 x Gearcase Seal Kit (396351) containing:
- Ball Detent (0316506)
- Reverse Gear Bushing (0319635)
- Retaining Ring (0319747)
- Cotter Pin (0303049)
- Clutch Dog Cradle (0328311)
- Propeller Shaft Assembly (0439143)
- Pinion Thrust Bearing Assembly (0388027)
- Pin & Washer Pivot (0308376)
- Roller Bearing Assembly (0386186)
- Reverse Gear (0327655)
- Thrust Washer (0327716)
- O-Ring (0338518)
- Forward Gear & Bushing Assembly (0392475)
- Pin (0302504)
- Pinion Gear, Driveshaft (0351147)
- Thrust Washer (0319684)
- Clutch dog Shifter (0337020)
- Shift Lever (0337019)
- Housing Retaining Plate (0319746)
- Fill & Drain Plug Screw (0307551)
- Lower Thrust Washer (0330441)
- Propeller Screw (0319743)
- Washer (0332584)
- Yoke & Connector (0390023)
- Detent (0327070)
Installation Notes
- Drain the gearcase lubricant completely into an approved container.
- Following the manufacturer's service manual, carefully disassemble the lower unit.
- Remove all old seals, gaskets, and O-rings, paying close attention to their orientation.
- Thoroughly clean all sealing surfaces of debris and residue. Inspect housings for cracks or corrosion.
- Lightly lubricate new seals and O-rings with marine grease to ensure smooth installation.
- Install the new components from the kit in the reverse order of disassembly.
- Confirm all parts are seated correctly and retaining rings or clips are secure.
- Reassemble the gearcase and torque all fasteners to the manufacturer-specified values.
- Refill the gearcase with fresh, recommended lower unit lubricant.
- Before operating the engine under load, check for any signs of lubricant leakage.
Troubleshooting & FAQ
How do I know if this seal kit fits my outboard?
This kit is designed for Johnson/Evinrude 20-35 HP outboards. Specifically, it fits 20–25 HP models from 1985–2005 and 30–35 HP models from 1977–2005. Always cross-reference your engine's OEM part number with 396351 or 777559 to ensure a perfect match.
What are the signs of a failing gearcase seal?
Common indicators include milky or water-contaminated gear lube, visible oil leaks around the propeller shaft or driveshaft, or a metallic sheen in the drained lubricant, which can indicate water intrusion and subsequent bearing wear.
Is any special tool required for installation?
While many components can be replaced with standard mechanic's tools, a seal puller and a bearing driver set are highly recommended for removing old seals and correctly pressing in new ones without causing damage. Always consult your service manual for tool recommendations.
How often should gearcase seals be replaced?
There is no fixed replacement interval, but it is best practice to inspect for leaks annually when changing the gear lube. Seals should be replaced whenever the lower unit is disassembled for other service or immediately if you detect water intrusion.
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.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
