Gearcase Seal Kit – Fits Johnson Evinrude 40–75 HP (Replaces 396355, 777562, 9-74102, 87603, 18-2659)

$49.99

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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 complete Gearcase Seal Kit is designed to restore the lower unit on Johnson and Evinrude 40–75 HP, 2-Cylinder and 3-Cylinder outboards manufactured between 1976 and 1988. It provides all necessary seals, gaskets, and O-rings to address leaks and perform a full reseal of the gearcase, preventing water intrusion and oil loss.

This kit directly replaces Johnson/Evinrude OEM part 396355 and serves as an interchange for Sierra 18-2659, Mallory 9-74102, GLM 87603, and SEI 95-365-11K.

Installs in the lower unit gearcase.
Features a machined exterior for precise fitment.
Includes all required gaskets, O-rings, and oil seals for a comprehensive overhaul.

Part Number Matrix

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

Brand	Part Number
Johnson / Evinrude	396355 / 0396355
Johnson / Evinrude	777562
UanofCn	396355
Sierra Marine	18-2659
Mallory Marine	9-74102
GLM	87603
SEI Marine	95-365-11K

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Johnson/Evinrude models, this kit is designed for a wide range of 2-stroke outboards from 1976 to 1988. Please verify your specific horsepower and model details against the table.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Johnson/Evinrude	All	40	2-Stroke	1976–1988	0396355 / 396355
Johnson/Evinrude	All	48	2-Stroke	1976–1988	0396355 / 396355
Johnson/Evinrude	All	50	2-Stroke	1976–1988	0396355 / 396355
Johnson/Evinrude	All	55	2-Stroke	1976–1988	0396355 / 396355
Johnson/Evinrude	All	60	2-Stroke	1976–1988	0396355 / 396355	2-cylinder models
Johnson/Evinrude	Small Gearcase	75	2-Stroke	1976–1988	0396355 / 396355

Technical Specs

Product Type: Lower Unit Seal Kit
Installation: Lower unit gearcase
Housing Material: N/A
Dimensions: 6.0 x 7.13 x 1.5 inches (152.4 x 181.1 x 38.1 mm)
Weight: 2.82 ounces (0.08 kg)
Other Technical Attributes: Machined exterior
Warranty: Comprehensive customer satisfaction warranty covering parts and labor.

What’s in the Box

1 x Impeller Housing Gasket (319586)
1 x Oil Seal (321466)
2 x Oil Seal (321467)
1 x Oil Seal (332205)
1 x Foam Seal (305762)
1 x Rubber Seal (324937)
1 x Gasket, Shift Housing Cover (314082)
2 x Washer (311598)
1 x O-Ring (302588)
1 x O-Ring (307853)
1 x O-Ring (318372)
1 x O-Ring (320303)
2 x O-Ring (333572)
3 x Quad Ring (332584)

Installation Notes

Place a drain pan under the lower unit and remove the drain/fill screws to empty the gearcase oil.
Disconnect the shift linkage and remove the bolts securing the lower unit to the engine's midsection.
Carefully lower and remove the gearcase assembly from the outboard.
Disassemble the propeller shaft bearing carrier and driveshaft components to access the old seals.
Thoroughly clean all sealing surfaces, removing any old gasket material, sealant, or corrosion.
Carefully install the new O-rings, gaskets, and oil seals from the kit, ensuring correct orientation.
Lubricate new seals and O-rings with marine grease to prevent damage during assembly.
Reassemble the gearcase components, ensuring proper alignment.
Reinstall the lower unit onto the midsection, reconnect the shift linkage, and torque all bolts to manufacturer specifications.
Refill the gearcase with the correct type and amount of new lower unit lubricant, using new washers on the drain/fill screws.

Troubleshooting & FAQ

How do I know if this seal kit fits my engine?

This kit is specifically for Johnson and Evinrude 40-75 HP outboards from 1976–1988. The most reliable method is to cross-reference your engine's original part number with those listed in our Part Number Matrix, such as OEM #396355 or Sierra #18-2659.

What are the signs of a failing gearcase seal?

Common signs include milky or creamy-looking gear lube (indicating water intrusion), a visible oil leak around the propeller shaft or driveshaft, or metal shavings in the oil, which can result from water-induced corrosion and wear.

How often should gearcase seals be replaced?

It's good practice to inspect for leaks every season. We recommend replacing the seals every 5-7 years as preventative maintenance, or immediately if you notice any signs of leaks or water contamination in the gear oil.

Is this kit the same as the original Johnson/Evinrude part?

This is an aftermarket kit engineered to meet or exceed OEM specifications. It contains all the necessary components for a complete gearcase reseal, similar to the OEM kit, but at a more competitive price.

Can I replace just one leaking seal instead of the whole kit?

While it's possible, it is not recommended. If one seal has failed due to age or wear, others are likely to fail soon. This comprehensive kit ensures all potential failure points are addressed at once, saving you from future repairs and potential gearcase damage.

What tools are needed for this installation?

You will need a standard set of mechanic's tools, including socket/ratchet sets, screwdrivers, a drain pan, and potentially a seal puller and driver set. A torque wrench is essential for reassembly to ensure bolts are tightened to the correct specifications.

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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