Gearcase Lower Unit Seal Kit – Fits Johnson/Evinrude 8–15 HP Outboard Boat Motors (Replaces 0396350, 0777568, 18-2656)

$35.00

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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 Lower Unit Seal Kit is designed for Johnson and Evinrude 8 HP to 15 HP outboard boat motors, covering a wide range of models from 1974 to 2007. It provides a complete solution for rebuilding the lower unit, preventing water intrusion and oil leaks to maintain peak performance.

This kit serves as a direct replacement for multiple OEM and aftermarket part numbers, including Johnson/Evinrude 0396350 and 0777568, Sierra 18-2656, and GLM 87602.

Engineered for durability in harsh freshwater and saltwater environments.
Made with high-quality materials to meet or exceed original equipment specifications.
Contains all necessary seals, o-rings, and washers for a comprehensive service.

Part Number Matrix

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

Brand	Part Number
Johnson/Evinrude (OEM)	0396350, 0777568
QuickMarine	396350
SeaSierra	0396350, 0777568
Sierra	18-2656
GLM	87602
Mallory	9-74100
SEI Marine	95-361-11K

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Johnson/Evinrude Models: This kit covers extensive 2-stroke and 4-stroke models. Note the slight variations in year ranges from different sources and verify against your specific engine serial number if unsure.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.
Johnson/Evinrude	Multiple	8	4-Stroke	1995–2004	0396350, 0777568
Johnson/Evinrude	Multiple	9.9	2-Stroke	1974–2007	0396350, 0777568
Johnson/Evinrude	Multiple	9.9	4-Stroke	1995–2004	0396350, 0777568
Johnson/Evinrude	Multiple	10	2-Stroke	1974–2007	0396350, 0777568
Johnson/Evinrude	Multiple	15	2-Stroke	1974–2007	0396350, 0777568
Johnson/Evinrude	Multiple	15	4-Stroke	1995–2004	0396350, 0777568

Technical Specs

Product Type: Gearcase Lower Unit Seal Kit
Material: Made of high-quality materials, durable and long-lasting even in harsh marine environments.
Weight: 4.9 ounces (0.14 kg)
Product Dimensions: 12" L x 10" W x 3" H
Warranty: 1-Year Manufacturer Warranty

What’s in the Box

Oil Seal (Replaces 318972/318971, 18-2025)
Oil Seal (Replaces 321480, 18-2028)
Oil Seal (Replaces 321481, 18-2029)
Oil Seal (Replaces 342247)
Drain/Fill Plug Washer (Replaces 311598, 18-4248)
O-Ring (Replaces 301877, 18-7100)
O-Ring (Replaces 380627/308627, 18-7104)
O-Ring (Replaces 307853/322598, 18-7120)
O-Ring (Replaces 319085, 18-7139)
O-Ring (Replaces 333572, 18-7145)
Screw and Washer - Oil Drain/Fill (Replaces 307551)
Seal - Pivot Pin (Replaces 307853)
Washer - Shift Rod Bushing (Replaces 321738)
Washer - Pivot Pin to Gearcase (Replaces 332584)

Installation Notes

Professional installation is recommended. The following are generic steps and may not match your specific model. Always consult a service manual for your engine.

Disconnect the battery and remove the propeller.
Place a drain pan under the lower unit and remove the drain/fill screws to empty the gear oil.
Remove the bolts securing the gearcase (lower unit) to the engine midsection and carefully lower it.
Disassemble the gearcase as required to access the propeller shaft, driveshaft, and shift rod seals.
Carefully remove old seals, o-rings, and gaskets, taking care not to scratch any metal surfaces.
Thoroughly clean all mating surfaces and seal cavities.
Lightly lubricate new seals and o-rings with marine grease before installation.
Install the new seals using an appropriate seal driver or socket to ensure they are seated evenly.
Reassemble all gearcase components in reverse order, torquing bolts to manufacturer specifications.
Reinstall the lower unit, install new drain/fill plug washers, and refill with fresh gearcase oil.

Troubleshooting & FAQ

How do I confirm this kit fits my specific Evinrude/Johnson motor?

The best way is to match your engine's model and year to our compatibility table. The year ranges provided (e.g., 1974–2007) are comprehensive, but always double-check with the OEM part number (0396350 or 0777568) listed in your service manual.

What are the signs that my gearcase seals are failing?

Common signs include milky or creamy-looking gear oil (indicating water intrusion), visible oil leaks around the propeller shaft or drain plugs, or metal shavings in the oil. You may also hear unusual grinding noises from the lower unit.

How often should lower unit seals be replaced?

It's good practice to inspect your gear oil for water at every oil change (annually or every 100 hours). Seals should be replaced preventatively every 3-5 years in saltwater or commercial use, or immediately if you find evidence of leaks or water contamination.

Is this aftermarket kit as reliable as OEM parts?

Yes. This is an aftermarket replacement part, not OEM. It is manufactured in an ISO 9001 certified facility and made from high-quality materials designed to meet or exceed the performance and longevity of the original parts.

Do I need special tools to install this seal kit?

While basic hand tools are required, you may also need a seal puller, a seal driver set (or appropriately sized sockets), and a torque wrench. A pressure/vacuum tester is also highly recommended to test the seals before and after installation.

What is the most common cause of premature seal failure?

Fishing line or other debris wrapped around the propeller shaft is a primary cause. It can cut into the prop shaft seal, allowing water to enter and oil to leak out. Regular inspection of this area can prevent major damage.

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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