Lower Unit Seal Kit for Johnson/Evinrude 25–50 HP 2-Stroke Outboards — Replaces 433550 and Sierra 18-2694
Lower Unit Seal Kit for Johnson/Evinrude 25–50 HP 2-Stroke Outboards — Replaces 433550 and Sierra 18-2694 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Lower Unit Seal Kit for Johnson/Evinrude 25–50 HP 2-Stroke Outboard...
Lower Unit Seal Kit for Johnson/Evinrude 25–50 HP 2-Stroke Outboards — Replaces 433550 and Sierra 18-2694 is backordered and will ship as soon as it is back in stock.
Product Details
This complete lower unit seal kit is intended to reseal the gearcase on compatible Johnson/Evinrude 2-stroke outboard engines. The listed applications include 25 HP models from 1990–1995 with the D suffix, 40 HP models from 1989 and later, 48 HP models from 1989–1996, and 50 HP models from 1989 and later.
The kit is listed as a replacement for Johnson/Evinrude references 433550, 0433550, and 777551, as well as aftermarket references Sierra 18-2694, GLM 87614, and Mallory 9-74104. Always compare your engine model, year, suffix, original part, and component layout before ordering.
- Complete seal and gasket kit for a compatible gearcase or lower-unit reseal.
- Includes seals, O-rings, gaskets, a drain plug, and related sealing hardware.
- Designed as an aftermarket replacement for the listed applications and reference numbers.
Part Number Matrix
Use the following references to compare the listed OEM and aftermarket numbers with the part being replaced.
| Brand | Part Number |
|---|---|
| Johnson/Evinrude | 433550 / 0433550 / 777551 |
| Sierra | 18-2694 |
| GLM | 87614 |
| Mallory | 9-74104 |
Engine & Model Compatibility
The applications below reflect the listed fitment range. Confirm the complete model designation, year, suffix, and serial information against your engine before installation.
| 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 and later | 433550 | Verify the complete model designation |
| Johnson/Evinrude | Outboard | 48 | 2-Stroke | 1989–1996 | 433550 | Verify the complete model designation |
| Johnson/Evinrude | Outboard | 50 | 2-Stroke | 1989 and later | 433550 | Verify the complete model designation |
Technical Specifications
- Product Type
- Gearcase/lower-unit seal kit
- Application
- Compatible Johnson/Evinrude 2-stroke outboard gearcases
- Installation
- Aftermarket replacement
- Connection
- Lower unit/gearcase
- Included Materials
- Seals, O-rings, gaskets, and related sealing hardware
- Use
- Lower-unit or gearcase resealing
What’s in the Box
- 1 × O-ring (305270)
- 1 × O-ring (338522)
- 1 × Wear plate gasket (336530)
- 1 × O-ring (310327/910582)
- 1 × O-ring (317178)
- 1 × O-ring (553126)
- 1 × O-ring (318372)
- 1 × Seal (333758)
- 1 × Oil seal (321466)
- 1 × Oil seal (332205)
- 1 × Oil seal (342786)
- 1 × Oil seal (342887)
- 1 × Seal (315748/341732)
- 1 × Gasket (311598)
- 1 × Drain-plug screw (318544)
- 1 × Housing seal ring (324981)
- 1 × Drain plug (309243)
- 1 × O-ring (336982)
- 1 × Retaining screw (324852)
- 1 × 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 drain the old lubricant.
- 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, recording the order and orientation of removed parts.
- Remove the old seals, O-rings, and gaskets from the housing, bearing carriers, shafts, and other sealing surfaces.
- Clean the sealing surfaces thoroughly and remove old adhesive, corrosion, and debris.
- Install the replacement seals, gaskets, and O-rings from the kit. Use sealants only where specified by the applicable service manual.
- Reassemble the lower-unit components in the correct order and torque fasteners according to the manufacturer’s service specifications.
- Reinstall the lower unit onto the engine and reconnect the shift linkage.
- Fill the gearcase with the recommended marine gear lubricant through the lower drain opening until lubricant reaches the upper opening. Reinstall both drain screws with their replacement sealing components.
Troubleshooting & FAQ
How do I know if my lower-unit seals are failing?
Common signs include milky or water-contaminated gear lubricant, visible oil leaks around the propeller shaft or driveshaft, or a metallic sheen in the drained lubricant. These symptoms can also indicate internal wear or other gearcase problems, so inspect the unit before replacing seals.
Is this kit compatible with a 25 HP engine from 1989?
The listed 25 HP application begins with 1990 models and specifies the D suffix. A 1989 25 HP engine is outside that listed range. Verify the exact model designation, suffix, serial information, and original seal-kit reference before ordering.
When should lower-unit seals be inspected?
Inspect the gearcase seals during routine annual service and whenever the lower unit is opened for related repairs. Replace damaged, hardened, or leaking seals and renew sealing components whenever required by the service procedure.
Do I need special tools for installation?
Standard hand tools may be sufficient for some steps, but a bearing-carrier puller, propeller-shaft puller, and suitable seal-installation drivers are recommended where required by the gearcase design. Using the correct tools helps prevent damage and ensures that seals are seated correctly.
Is this an OEM kit?
No. This listing is for an aftermarket replacement kit. The OEM and aftermarket numbers shown above are reference numbers used to help confirm application and interchange.
What are the shipping and return terms?
Shipping availability, delivery estimates, warranty coverage, and return eligibility are determined by the applicable order and store policies. Review the current checkout and policy information before placing an order.
Safety & Important Information
- Confirm the engine brand, horsepower, stroke, year, suffix, serial information, and original part references before purchase.
- Compare the kit contents and component dimensions with the parts being replaced. Do not install a component that does not match the service-manual requirements.
- This is an aftermarket replacement kit, not an OEM component.
- Professional installation is recommended because lower-unit disassembly and sealing affect gearcase lubrication and water protection.
- Follow the applicable manufacturer service manual for seal orientation, sealant use, fastener torque, lubricant type, and testing.
About Sea Sierra
- Marine Replacement Parts — We supply aftermarket marine components for repair and maintenance applications.
- Application-Focused Listings — Product references and fitment details are provided to help customers compare replacement parts.
- Value-Oriented Service — We aim to provide practical replacement solutions for marine maintenance needs.
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