Upper Gearcase Seal Kit – Fits MerCruiser Bravo I, II, III, X, XR, XZ & Blackhawk (Replaces 26-16709A1, 26-16709A2)
Upper Gearcase Seal Kit – Fits MerCruiser Bravo I, II, III, X, XR, XZ & Blackhawk (Replaces 26-16709A1, 26-16709A2) is backordered and will ship as soon as it is back in stock.
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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.).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Upper Gearcase Seal Kit – Fits MerCruiser Bravo I, II, III, X, XR, ...
Product Details
This aftermarket Upper Gearcase Seal Kit – Fits MerCruiser Bravo I, II, III, X, XR, XZ & Blackhawk Stern Drives (Replaces 26-16709A1, 26-16709A2) contains all necessary components to reseal the upper gearcase on most MerCruiser Bravo stern drives from 1988 and newer. It is compatible with Bravo I, II, III, X, XR, XZ, and Blackhawk (1994–1995) models.
This kit serves as a direct interchange for MerCruiser 26-16709A1 and 26-16709A2, Sierra 18-2643, GLM 87480, and Mallory 9-74301.
- Engineered for installation to OEM specifications.
- Includes a comprehensive set of O-rings, seals, and gaskets for a complete service.
- Designed for use in marine stern drive systems.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| MerCruiser | 26-16709A1 |
| MerCruiser | 26-16709A2 |
| Sierra | 18-2643 |
| GLM | 87480 |
| Mallory | 9-74301 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Years | OEM Part No. |
|---|---|---|---|
| MerCruiser | Bravo I | 1988 and Up | 26-16709A1/26-16709A2 |
| MerCruiser | Bravo II | 1988 and Up | 26-16709A1/26-16709A2 |
| MerCruiser | Bravo III | 1988 and Up | 26-16709A1/26-16709A2 |
| MerCruiser | Blackhawk | 1994–1995 | 26-16709A1/26-16709A2 |
Technical Specs
- Product Type
- Upper Gearcase Seal Kit
- Installation
- OEM Specification
- Housing Material
- Various (O-rings, seals, washers)
- Compatible Systems
- Bravo I, II, III, X, XR, XZ, Blackhawk
- Application
- Upper Gearcase
What’s in the Box
- 1 x O-Ring 25-45710
- 1 x O-Ring 25-48171
- 2 x O-Ring 25-62705
- 1 x O-Ring 25-35027
- 1 x Seal 16755Q1
- 2 x Outdrive Seal 12-19183
- 1 x Gear Housing Drain Screw Gasket 12708
- 1 x Spring Kit 24-17997A1
- 1 x Oil Seal 12709
- 1 x Oil Seal 26-807006
- 4 x Keeper 97351
- 1 x O-Ring 25-97387
- 2 x O-Ring 29845
- 1 x O-Ring 861844
- 1 x O-Ring 25-70937
- 1 x O-Ring 20826
- 1 x O-Ring 69201
Installation Notes
- Place the drive in the full-down position and drain the gear lube completely.
- Remove the upper gearcase unit from the lower unit according to your service manual.
- Carefully disassemble the driveshaft housing, keeping all components in order.
- Remove all old O-rings, seals, and gaskets from the housing and associated parts.
- Thoroughly clean all mating surfaces, ensuring they are free of old adhesive, corrosion, and debris.
- Lightly lubricate the new seals and O-rings with 2-4-C marine grease or gear oil before installation.
- Using appropriate seal drivers, press the new seals into place squarely without damaging them.
- Reassemble the unit, ensuring all components are installed in the correct order and orientation.
- Torque all fasteners to the manufacturer's specified values.
- Once reassembled, pressure test the housing to check for leaks before reinstalling on the boat.
- Refill the drive with fresh, high-quality marine gear lubricant.
Troubleshooting & FAQ
How do I know if my upper gearcase needs resealing?
Common signs of seal failure include milky, water-contaminated gear lube (check the reservoir), visible oil leaks on the drive or in the water, or a frequent need to top off the gear lube.
Is this kit compatible with all MerCruiser Bravo drives?
It fits the vast majority of Bravo I, II, and III models from 1988 and newer, plus Bravo X, XR, XZ, and the 1994-1995 Blackhawk. However, always verify compatibility by checking your drive model and serial number against the provided lists. When in doubt, consult your service manual or a professional.
What causes upper gearcase seals to fail?
The primary causes are age-related wear and tear, damage from fishing line or debris wrapping around the prop shaft, improper installation (nicked or unseated seals), and operating with low or contaminated gear lube.
Are special tools required for installation?
Yes, professional installation requires specialized tools such as a bearing carrier tool, seal drivers, and a calibrated torque wrench. Attempting the job without these tools can lead to damage to the new seals or the gearcase housing itself.
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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