Lower Unit Seal Kit – Fits Johnson/Evinrude 25-50 HP 2-Stroke (Replaces 433550, 18-2694)
Lower Unit Seal Kit – Fits Johnson/Evinrude 25-50 HP 2-Stroke (Replaces 433550, 18-2694) 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 Seal Kit – Fits Johnson/Evinrude 25-50 HP 2-Stroke (Repl...
Lower Unit Seal Kit – Fits Johnson/Evinrude 25-50 HP 2-Stroke (Replaces 433550, 18-2694) is backordered and will ship as soon as it is back in stock.
Product Details
This complete Lower Unit Seal Kit – Fits Johnson/Evinrude 25-50 HP 2-Stroke (Replaces 433550, 18-2694) contains all necessary seals, gaskets, and O-rings to rebuild the gearcase on compatible Johnson/Evinrude outboard engines. It is designed for 2-stroke models including 25 HP (1990–1995, D suffix only), 40 HP (1989 & Up), 48 HP (1989–1996), and 50 HP (1989 & Up).
This kit provides a direct replacement for Johnson/Evinrude OEM parts 433550, 0433550, and 777551, as well as aftermarket equivalents Sierra 18-2694, GLM 87614, and Mallory 9-74104.
- Designed for direct OEM-replacement installation.
- Comprehensive kit for a full gearcase reseal.
- Constructed from durable rubber, metal, and synthetic materials to withstand the marine environment.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Johnson/Evinrude | 433550 / 0433550 / 777551 |
| Sierra | 18-2694 |
| GLM | 87614 |
| Mallory | 9-74104 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Johnson/Evinrude | Outboard | 25 | 2-Stroke | 1990–1995 | 433550 | D suffix only |
| Johnson/Evinrude | Outboard | 40 | 2-Stroke | 1989 & Up | 433550 | |
| Johnson/Evinrude | Outboard | 48 | 2-Stroke | 1989–1996 | 433550 | |
| Johnson/Evinrude | Outboard | 50 | 2-Stroke | 1989 & Up | 433550 |
Technical Specs
- Product Type
- Gearcase/Lower Unit Seal Kit
- Installation
- OEM Replacement
- Connection
- Lower Unit/Gearcase
- Housing Material
- Various (Rubber, Metal, Synthetic)
- Warranty
- Varies by manufacturer: 1 Year (Aftermarket)
- Other Technical Attributes
- Complete seal kit for rebuilding lower unit
What’s in the Box
- 1 x O-Ring (305270)
- 1 x O-Ring (338522)
- 1 x Wear plate gasket (336530)
- 1 x O-Ring (310327/910582)
- 1 x O-Ring (317178)
- 1 x O-Ring (553126)
- 1 x O-Ring (318372)
- 1 x Seal (333758)
- 1 x Oil seal (321466)
- 1 x Oil seal (332205)
- 1 x Oil seal (342786)
- 1 x Oil seal (342887)
- 1 x Seal (315748/341732)
- 1 x Gasket (311598)
- 1 x Drain plug Screw (318544)
- 1 x Housing Seal ring (324981)
- 1 x Drain plug (309243)
- 1 x O-Ring (336982)
- 1 x Retaining screw (324852)
- 1 x Washer seal ring (332584)
Installation Notes
- Place a drain pan under the lower unit and remove the upper and lower gear oil drain screws to empty the old oil.
- Disconnect the shift linkage and remove the bolts securing the lower unit to the midsection. Carefully lower the unit.
- Disassemble the gearcase housing, propeller shaft assembly, and driveshaft components, noting the order of removal.
- Carefully remove all old seals, o-rings, and gaskets from the housing, bearing carriers, and shafts.
- Clean all sealing surfaces thoroughly, ensuring they are free of old adhesive, corrosion, or debris.
- Install the new seals, gaskets, and o-rings from the kit, using appropriate sealants where specified by the service manual.
- Reassemble the lower unit components in reverse order of disassembly, torquing fasteners to manufacturer specifications.
- Reinstall the lower unit onto the engine and reconnect the shift linkage.
- Fill the gearcase with new, recommended marine gear lubricant from the bottom drain hole until it seeps from the top hole. Re-install both drain screws with new gaskets.
Troubleshooting & FAQ
How do I know if my lower unit seals are failing?
Common signs include milky or water-contaminated gear lube (indicating water intrusion), visible oil leaks around the propeller shaft or driveshaft, or a metallic sheen in the drained oil, which can point to internal wear caused by water damage.
Is this kit compatible with a 25 HP engine from 1989?
No. This kit is specifically listed for 25 HP models manufactured from 1990–1995 that have a "D" suffix. It is not compatible with earlier models. Please verify your engine details before ordering.
What is the recommended replacement interval for gearcase seals?
As a best practice, lower unit seals should be inspected during every annual service. We recommend a full replacement every 3-5 years or anytime the lower unit is serviced for other work, like a water pump replacement, to ensure long-term reliability.
Do I need special tools for installation?
While standard hand tools can complete most of the job, specialized tools like a bearing carrier puller, a propeller shaft puller, and seal installation drivers are highly recommended. Using the correct tools prevents damage to the components and ensures the new seals are seated correctly.
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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