Lower Unit Gearcase Seal Kit – Fits Mercruiser Alpha I Gen II (Replaces 26-816575A3, 26-816575A1, GLM 87511, 9-74206, 18-2646-1)
Lower Unit Gearcase Seal Kit – Fits Mercruiser Alpha I Gen II (Replaces 26-816575A3, 26-816575A1, GLM 87511, 9-74206, 18-2646-1) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Lower Unit Gearcase Seal Kit – Fits Mercruiser Alpha I Gen II (Repl...
Product Details
This Lower Unit Gearcase Seal Kit is designed to fit MerCruiser Alpha One Gen 2 sterndrive models manufactured from 1991 to the present. It provides a reliable solution for maintaining and repairing your lower unit to prevent leaks and protect internal components.
This kit serves as a direct interchange for several part numbers, including Mercury-Mercruiser 26-816575A3 and 26-816575A1, GLM 87511, Sierra 18-2646-1, and EMP 18-2646-1.
- Effectively prevents lubricant leakage and protects internal metal parts from rust and corrosion.
- Constructed from high-quality rubber materials for durability and a reliable seal against the elements.
- Engineered to provide excellent resistance against dust and water intrusion, extending the life of your gearcase.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Mercury-Mercruiser | 26-816575A3 |
| Mercury-Mercruiser | 26-816575A1 |
| SAIL MARINE | 26-816575A3 |
| Qnbes | 26-816575A3 |
| GLM | 87511 |
| Sierra | 18-2646-1 |
| Sierra | 9-74206 |
| Sierra | 47-26461 |
| EMP | 18-2646-1/26-00834 |
Engine & Model Compatibility
Confirm your engine model and year in the table below to ensure accurate fitment.
| Brand | Model | Years | OEM Part No. | Notes |
|---|---|---|---|---|
| MerCruiser | Alpha One Gen II | 1991–Present | 26-816575A3 | Replaces 26-816575A1 |
Technical Specs
- Product Type
- Lower Unit Gearcase Seal Kit
- Material
- High-quality rubber materials
- Dimensions
- 16.0 x 13.5 x 2.5 cm
- Weight
- 0.218 kg (0.48 lb)
What’s in the Box
- 1 x Lower Unit Gearcase Seal Kit
Installation Notes
- Drain the gear lube from the lower unit completely.
- Carefully remove the lower unit from the sterndrive assembly.
- Disassemble the necessary components to access the old seals, noting their order and orientation.
- Thoroughly clean all sealing surfaces, ensuring they are free of old sealant, oil, and debris.
- Install the new seals using appropriate drivers to ensure they are seated correctly without damage.
- Lubricate the new seals and shafts with marine-grade grease before reassembly.
- Reassemble the lower unit components in the reverse order of disassembly.
- Reinstall the lower unit to the sterndrive, ensuring proper alignment and torque specifications.
- Refill the gearcase with the manufacturer-specified lower unit lubricant to the correct level.
- After a short run time, check for any signs of leaks before returning to full operation.
Troubleshooting & FAQ
How do I know if this seal kit will fit my sterndrive?
This kit is specifically designed for MerCruiser Alpha One Gen II models from 1991 to the present. Please verify your sterndrive model and year before purchasing. You can also compare your old part numbers to those listed in our Part Number Matrix to confirm compatibility.
What are the signs my gearcase seals are failing?
Common signs of a failing seal include milky or discolored gear lube (indicating water intrusion), visible oil leaks around the propeller shaft or lower unit housing, or a persistent need to top off the gear lube.
How often should lower unit seals be replaced?
There is no fixed replacement interval, but it's good practice to inspect for leaks annually or during regular maintenance. Seals are typically replaced whenever the lower unit is disassembled for other service, or immediately if any signs of leakage are detected.
Does this kit include all the necessary seals for a complete rebuild?
This is a comprehensive lower unit gearcase seal kit containing the primary seals for the application. However, as contents may vary, we recommend comparing the product images to the specific seals you need to replace on your sterndrive to ensure it meets the requirements of your job.
Is this a genuine Mercury-Mercruiser (OEM) part?
This is a high-quality aftermarket replacement part, not an OEM component. It is engineered to meet or exceed OEM specifications and is manufactured in an ISO 9001 certified facility to ensure performance and reliability.
How fast is shipping?
We offer fast worldwide shipping, with typical transit times of 5–15 days for standard delivery. Standard shipping is free to most regions, and expedited options may be available at checkout.
What is the warranty on this part?
This part 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 for unused items in their original packaging are accepted within our standard return period.
Safety & Important Info
- Verify images and specifications against your original part before ordering. If anything differs—even if your model appears on a compatibility list—do not purchase.
- This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.
- Professional installation is strongly recommended to ensure safety and optimal performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
- Fast Global Fulfillment — We offer free standard delivery to most regions, with parts typically arriving in 5–15 days.
- Manufacturer-Direct Value — Our model provides fair pricing without compromising on materials or quality control.
Payment & Security
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