Lower Unit Gearcase Seal Kit – Fits Johnson/Evinrude 40HP, 48HP & 50HP 2-Stroke Outboards (Replaces 433550, 0777551)
Lower Unit Gearcase Seal Kit – Fits Johnson/Evinrude 40HP, 48HP & 50HP 2-Stroke Outboards (Replaces 433550, 0777551) is backordered and will ship as soon as it is back in stock.
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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.
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Lower Unit Gearcase Seal Kit – Fits Johnson/Evinrude 40HP, 48HP &am...
Lower Unit Gearcase Seal Kit – Fits Johnson/Evinrude 40HP, 48HP & 50HP 2-Stroke Outboards (Replaces 433550, 0777551) is backordered and will ship as soon as it is back in stock.
Product Details
This Lower Unit Gearcase Seal Kit is designed to service the gearcases of Johnson and Evinrude 40HP, 48HP, and 50HP 2-stroke outboard engines manufactured from 1989 to 2005. It provides all necessary seals and gaskets to restore watertight integrity and prevent leaks.
The kit serves as a direct interchange for several OEM and aftermarket part numbers, including Sierra 18-2694, GLM 87614, and Mallory 9-74104.
- Installs as a direct OEM-equivalent replacement.
- Includes a complete set of seals, O-rings, and gaskets for a full service.
- Built from durable rubber and metal components to withstand the marine environment.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Johnson/Evinrude (OEM) | 433550 | Primary interchange |
| Johnson/Evinrude (OEM) | 0777551 | |
| Sierra | 18-2694 | |
| GLM | 87614 | |
| Mallory | 9-74104 | |
| SeaSierra | 433550 | |
| JUWEVAZU | 433550 | |
| GHmarine | 433550 | |
| Red Rhino | JE-270 | |
| EMP | 26-07400 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Johnson/Evinrude owners, this kit covers a wide range of 2-stroke models. Pay close attention to horsepower, year, and specific notes to ensure a correct match.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Johnson/Evinrude | Various | 25 | 2-Stroke | 1990–1995 | 433550 | D suffix only |
| Johnson/Evinrude | Various | 40 | 2-Stroke | 1989 & Up | 433550 | |
| Johnson/Evinrude | Various | 48 | 2-Stroke | 1989–1996 | 433550 | |
| Johnson/Evinrude | Various | 50 | 2-Stroke | 1989 & Up | 433550 | Includes 1987 50HP gearbox applications |
Technical Specs
- Product Type
- Lower Unit Gearcase Seal Kit
- Installation
- Direct OEM Replacement
- Housing Material
- Rubber, Metal
- Housing Color
- Black
- Warranty
- 1 Year (GHmarine)
- Other Technical Attributes
- Complete kit containing all necessary seals, O-rings, and gaskets for lower unit service
What’s in the Box
- 1 x Gearcase Seal Kit (contains approximately 20 pieces)
- 1 x Installation Instructions
Installation Notes
- Position a drain pan under the lower unit and remove the upper and lower gear lube drain screws to empty the old oil.
- Remove the propeller and shift the outboard into neutral.
- Unbolt and carefully detach the lower unit (gearcase) from the outboard's midsection.
- Disassemble the gearcase components, including the water pump, driveshaft, and propeller shaft, taking photos to remember the order.
- Carefully pry out all old seals, O-rings, and gaskets from the housing and shafts. Avoid scratching the metal surfaces.
- Thoroughly clean all sealing surfaces with a suitable solvent to remove any old sealant, corrosion, or debris.
- Lightly lubricate the new seals and O-rings with 2-4-C marine grease before installation.
- Using appropriate seal drivers or sockets, press the new seals into place until they are fully seated.
- Reassemble all components in reverse order of disassembly, ensuring correct alignment.
- Reinstall the lower unit onto the outboard, tightening bolts to manufacturer torque specifications.
- Refill the gearcase with fresh, high-quality marine gear lubricant until it flows from the upper vent hole.
- Reinstall the vent and drain screws with new washers/seals from the kit, and check for leaks after a short period.
Troubleshooting & FAQ
How do I know this seal kit will fit my engine?
This kit is specifically for Johnson/Evinrude 40HP, 48HP, and 50HP 2-stroke outboards (1989–2005). The most reliable way to confirm fitment is to match your original part number to one listed in our Part Number Matrix. If uncertain, please contact us with your engine's model and serial number before purchasing.
What are the signs of a failing gearcase seal?
The most common symptom is milky, grey, or creamy-looking gear lube, which indicates water contamination. Other signs include visible oil leaks around the propeller shaft, driveshaft, or drain screws, and in severe cases, a burning smell or grinding noises from the lower unit.
How often should I replace my lower unit seals?
It is recommended to inspect lower unit seals annually during routine maintenance (like a water pump service). Proactive replacement is advised every 3-5 years, or immediately if you find evidence of water intrusion or oil leakage.
Are the components in this kit identical to the OEM version?
This kit is engineered to be a direct functional replacement and includes all the necessary seals, O-rings, and gaskets for a standard lower unit reseal on the specified models. While component materials and manufacturing processes are comparable to OEM standards, the exact contents may differ slightly from a factory kit, but all critical parts for the application are included.
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
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