Lower Unit Seal Kit – Fits Johnson/Evinrude 40-75 HP (Replaces 5000309, 0396349, 0777558)
Lower Unit Seal Kit – Fits Johnson/Evinrude 40-75 HP (Replaces 5000309, 0396349, 0777558) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
Lower Unit Seal Kit – Fits Johnson/Evinrude 40-75 HP (Replaces 5000...
Lower Unit Seal Kit – Fits Johnson/Evinrude 40-75 HP (Replaces 5000309, 0396349, 0777558) is backordered and will ship as soon as it is back in stock.
Product Details
This Lower Unit Seal Kit – Fits Johnson/Evinrude 40-75 HP (Replaces 5000309, 0396349, 0777558) is a comprehensive gearcase seal kit designed for Johnson/Evinrude 2-stroke 40-75 HP outboards (1975–2001) and Evinrude E-TEC 40-60 HP models (2004–2008). It includes all necessary seals, O-rings, gaskets, and hardware for a complete lower unit service.
It serves as a direct replacement for Johnson/Evinrude part numbers 5000309, 0396349, and 0777558, and provides an interchange for aftermarket equivalents including Sierra 18-8383, GLM 87601, and Mallory 9-74103.
- Direct replacement installation
- Designed for 2-stroke gasoline outboard engines
- Includes all essential seals, O-rings, gaskets, and screws for service
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Superseded By | Notes |
|---|---|---|---|
| Johnson/Evinrude | 0396349 | 5000309 | |
| Johnson/Evinrude | 0777558 | 5000309 | |
| Johnson/Evinrude | 5000309 | Current | |
| Sierra | 18-8383 | Aftermarket Cross-Reference | |
| GLM | 87601 | Aftermarket Cross-Reference | |
| Mallory | 9-74103 | Aftermarket Cross-Reference |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Johnson/Evinrude outboard motors, please verify your specific model, horsepower, and year range against the chart to ensure correct fitment.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Evinrude | E-TEC | 40 | 2-Stroke | 2004–2008 | 5000309 | Large Housing |
| Evinrude | E-TEC | 50 | 2-Stroke | 2004–2008 | 5000309 | Large Housing |
| Evinrude | E-TEC | 60 | 2-Stroke | 2004–2008 | 5000309 | Large Housing |
| Johnson/Evinrude | 3-Cylinder | 50 | 2-Stroke | 1995–2001 | 5000309 | |
| Johnson/Evinrude | 3-Cylinder | 60 | 2-Stroke | 1975–2001 | 5000309 | |
| Johnson/Evinrude | 3-Cylinder | 65 | 2-Stroke | 1975–2001 | 5000309 | |
| Johnson/Evinrude | 3-Cylinder | 70 | 2-Stroke | 1975–2001 | 5000309 | |
| Johnson/Evinrude | 3-Cylinder | 75 | 2-Stroke | 1975–1987 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.187 Bore | 40 | 2-Stroke | 1997–2001 | 5000309 | Large Housing |
| Johnson/Evinrude | 2-Cyl 3.187 Bore | 45 | 2-Stroke | 1997 | 5000309 | Large Housing |
| Johnson/Evinrude | 2-Cyl 3.187 Bore | 50 | 2-Stroke | 1995–1998 | 5000309 | Large Housing |
| Johnson/Evinrude | 2-Cyl 3.187 Bore | 55 | 2-Stroke | 1997–2001 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.600 Bore E-TEC | 40 | 2-Stroke | 2004–2008 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.600 Bore E-TEC | 50 | 2-Stroke | 2004–2008 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.600 Bore E-TEC | 55 | 2-Stroke | 2003–2005 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.600 Bore E-TEC | 60 | 2-Stroke | 2004–2008 | 5000309 | |
| Johnson/Evinrude | 3-Cyl 3.000 Bore | 60 | 2-Stroke | 1988 | 5000309 | |
| Johnson/Evinrude | 3-Cyl 3.000 Bore | 65 | 2-Stroke | 1985–1986 | 5000309 |
Technical Specs
- Product Type
- Gearcase/Lower Unit Seal Kit
- Installation
- Direct replacement
- Fuel Type
- Gasoline
- Engine Type
- 2-Stroke
- Housing Material
- Metal, Plastic, Rubber
- Dimensions
- Height: 152.4 mm (6.0 in); Width: 181.1 mm (7.13 in); Length: 38.1 mm (1.5 in)
- Weight
- 198.4 g (7 oz)
- Mounting Type
- Transom Mount
What’s in the Box
- 4 x Washer (0332584/18-7475)
- 4 x Screw Bearing Housing (0320041/0316564/0777794/18-2379)
- 2 x Fill & Drain Screw Seal (0311598/3852105/0777517/18-4248)
- 2 x Fill & Drain Plug Screw (0307551/0027283/0912625/0982851/0777602/18-2387)
- 2 x Upper & lower Seal (0330137/0310600/0321463/0321668/0317761/0313398/0777519/18-2001)
- 1 x Oil Seal (0342786/0769517/18-8325)
- 1 x Driveshaft Oil Retainer (Lower) (0321466/0313337/0318223/0777531/18-2059)
- 1 x Upper Driveshaft Oil Retainer (0332205/0777942/18-2064)
- 1 x Seal (0324937/0313656/0777908/18-2537)
- 1 x Gasket (0336530/0777867/18-2709)
- 1 x Impeller Housing Seal (0324981/0777871/18-7481)
- 1 x Solenoid to Gearcase Gasket (0314082/0320312/0777545/18-2855)
- 1 x O-Ring (0313446/0765593/18-7127)
- 1 x Driveshaft Bearing O-Ring (0313754/0310580/0313734/0777903/18-7128)
- 1 x Crankshaft to driveshaft O-Ring (0326649/0122678/0553127/0777902/18-7174)
- 1 x O-Ring (0318372/0777526/18-7137)
- 1 x Seal (0307853/0765640/18-7120)
- 1 x O-Ring (310967)
Installation Notes
- Disconnect the battery and shift linkage before starting. Drain the old gearcase oil completely.
- Unbolt and carefully remove the lower unit from the outboard's midsection.
- Disassemble the gearcase as required to access the propeller shaft, driveshaft, and shift shaft seals. Keep components organized.
- Carefully remove all old seals, O-rings, and gaskets. Thoroughly clean all mating surfaces and seal bores, removing any old sealant or corrosion.
- Lightly lubricate the new seals and O-rings with marine grease before installation to prevent damage.
- Press the new seals into place using an appropriate driver, ensuring they are seated squarely and to the correct depth.
- Reassemble all components in reverse order, following manufacturer torque specifications for all fasteners.
- Re-install the lower unit, reconnect all linkages, and refill the gearcase with the recommended new gear lube.
- Before operating the engine on the water, check for any signs of water or oil leaks.
Troubleshooting & FAQ
Will this kit fit my engine if it's in the listed year range?
While this kit is designed for the specified models and years, manufacturing variations can exist. We strongly recommend comparing the parts in the product images to your engine's original seals before ordering to guarantee a perfect match. Some customer reviews indicate potential fitment issues with certain engines in the compatibility range, so visual verification is the best policy.
What are the signs my lower unit seals are failing?
The most common signs of seal failure are milky, cloudy, or grey gear lube, which indicates water intrusion. You may also notice visible oil leaks around the propeller shaft or under the water pump housing, or find that you need to frequently top off the gearcase oil.
How often should I replace my lower unit seals?
It is best practice to inspect your lower unit seals every time you service your water pump impeller (typically every 1-2 years or 100-200 hours of use). To prevent catastrophic gear failure, you should replace the seals proactively if you see any signs of wear, cracking, brittleness, or leakage.
Are these seals different from the original OEM parts?
Our aftermarket seals are engineered to meet or exceed OEM specifications for fit, material quality, and durability. While they may have minor cosmetic differences, they are made from high-quality materials designed for the demands of the marine environment and provide a reliable, cost-effective alternative to OEM parts.
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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