Gearcase Seal Kit – Fits Johnson/Evinrude 40-75 HP (Replaces 5000309, 0396349, 0777558)
Gearcase 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
Free standard shipping on all orders under 1 KG
Gearcase Seal Kit – Fits Johnson/Evinrude 40-75 HP (Replaces 500030...
Product Details
This Gearcase Seal Kit is designed for a wide range of Johnson/Evinrude 40-75 HP, 3-cylinder engines (1975–2001) and specific E-TEC models (2004-2008). It provides a complete solution for servicing and resealing the lower unit to prevent water intrusion and oil leaks, ensuring the longevity and performance of your outboard motor.
The kit serves as a direct replacement for OEM part numbers OMC 5000309 and 0396349, BRP 0777558, and aftermarket equivalent Sierra 18-8383.
- Engineered for direct-replacement installation.
- Contains all essential seals, gaskets, and O-rings for a full gearcase service.
- Restores sealing integrity to prevent water contamination in the lower unit.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| OMC | 5000309 |
| OMC | 0396349 |
| BRP | 0777558 |
| Sierra | 18-8383 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit is verified for the following Johnson/Evinrude engines.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Evinrude | E-TEC | 40 | 2-Stroke | 2004–2008 | 5000309 | |
| Evinrude | E-TEC | 50 | 2-Stroke | 2004–2008 | 5000309 | |
| Evinrude | E-TEC | 60 | 2-Stroke | 2004–2008 | 5000309 | |
| Evinrude | E-TEC | 65 | 2-Stroke | 2008–2010 | 5000309 | Based on 2-Cyl 3.600 Bore data |
| 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 | 1975–2001 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.187 Bore Looper | 40 | 2-Stroke | 1999–2001 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.187 Bore Looper | 45 | 2-Stroke | 1997 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.187 Bore Looper | 50 | 2-Stroke | 1995–1998 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.187 Bore Looper | 55 | 2-Stroke | 1999–2001 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.600 Bore E-TEC | 40 | 2-Stroke | 2004–2010 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.600 Bore E-TEC | 50 | 2-Stroke | 2004–2010 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.600 Bore E-TEC | 55 | 2-Stroke | 2008–2010 | 5000309 | |
| Johnson/Evinrude | 2-Cyl 3.600 Bore E-TEC | 60 | 2-Stroke | 2005–2010 | 5000309 | |
| Johnson/Evinrude | 2-Cyl | 55 | 2-Stroke | 2003–2005 | 5000309 | |
| Johnson/Evinrude | 3-Cyl 3.000 Bore Looper | 60 | 2-Stroke | 1988 | 5000309 | |
| Johnson/Evinrude | 3-Cyl 3.000 Bore Looper | 65 | 2-Stroke | 1985–1986 | 5000309 |
Technical Specs
- Product Type
- Gearcase/Lower Unit Seal Kit
- Installation
- Direct replacement
- Weight
- 198.4 g (7 ounces)
- Dimensions
- Height: 6.0 in; Width: 7.13 in; Length: 1.5 in;
- Warranty
- 1 Year (based on aftermarket offerings)
- Other Technical Attributes
- Complete kit for lower unit sealing
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
- Drain the gearcase oil completely by removing the drain and vent plugs.
- Remove the propeller assembly from the propeller shaft.
- Unbolt and carefully lower the gearcase (lower unit) from the outboard's midsection.
- Disassemble the gearcase as required to access the driveshaft and propeller shaft seals. This typically involves removing the bearing carrier.
- Carefully extract all old seals, O-rings, and gaskets using appropriate tools, paying close attention to their orientation and location.
- Thoroughly clean all sealing surfaces and component bores, ensuring they are free of old sealant, corrosion, and debris.
- Lightly lubricate the new seals with marine grease and install them using a seal driver or appropriately sized socket to ensure they are seated evenly and without damage.
- Reassemble all components in reverse order, ensuring all O-rings and gaskets are correctly placed.
- Torque all bolts to the manufacturer’s specified values.
- Reinstall the gearcase, refill with fresh gear lubricant using new drain screw seals, and reinstall the propeller.
Troubleshooting & FAQ
How do I know if this kit fits my specific engine?
Review the detailed compatibility table, which lists applicable Johnson/Evinrude models, horsepower ratings, and year ranges. This kit is designed for 40-75 HP 3-cylinder and select E-TEC engines. For 100% certainty, it is always best practice to cross-reference the OEM part number (e.g., 5000309) with your engine's service manual or parts diagram.
What are the signs of a failing gearcase seal?
The most common symptom is milky, grey, or cloudy gear oil, which indicates water intrusion. Other signs include visible oil leaks around the propeller shaft or under the water pump housing, a consistent need to top off gear lubricant, or metallic shavings in the oil, suggesting internal component wear due to poor lubrication.
Is this a complete kit for a lower unit reseal?
Yes, this is a comprehensive aftermarket kit that includes the essential seals, O-rings, gaskets, and washers needed to perform a standard reseal of the gearcase lower unit. The "What’s in the Box" section provides a complete list of included components and their corresponding part numbers.
How often should gearcase seals be replaced?
It is recommended to inspect gearcase seals and oil during every annual service or every 100 hours of operation. Seals should be replaced immediately if any leaks are detected. It is also standard practice to replace all seals and gaskets whenever the gearcase is disassembled for any other repair or service.
What is the difference between OEM and this aftermarket kit?
This listing is an aftermarket replacement, not an OEM component. It is engineered to meet or exceed original equipment manufacturer (OEM) specifications using comparable, high-quality materials. Our parts are produced in an ISO 9002 certified facility and are batch-inspected to ensure consistent quality and fitment.
How fast do you ship and what does it cost?
We ship worldwide quickly, with typical transit times of 5–15 days for most regions. Standard shipping is free. If expedited shipping options are available for your location, they will be presented at checkout for an additional fee.
What is the warranty and return policy?
This product is covered by a 1-year warranty against manufacturing defects under normal marine use. If you encounter an issue, please contact our support team with your order details for assistance. Returns are accepted within our standard window, provided the item is unused and in its original packaging. Please see our full 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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