26-33144A2 18-2652 Lower Unit Gear Case Housing Seal Kit for MerCruiser Alpha One | JLM Marine

Lower Unit Gear Case Housing Seal Kit – Fits MerCruiser Alpha One (1964-1989)

This Lower Unit Gear Housing Seal Kit is designed for MerCruiser Alpha One Gen 1 sterndrives from 1964 to 1989, covering IA, IB, IC, EZ Shift, R, MR, and Alpha 1 models. It provides a complete seal solution for driveshaft and gear housing assemblies, ensuring reliable protection against water intrusion and gear oil leaks.

This kit directly replaces MerCruiser OEM part numbers 26-33144A2, 26-33144A1, and 26-89238A1, as well as aftermarket numbers 18-2652, 87510, and 9-74304. It fits a wide range of MerCruiser sterndrive outdrive and transom assemblies, including models 120, 140, 165, 228, 250, 260, 470, 485, 898, R-MR, Alpha One, and Alpha One SS series.

• Complete seal kit for lower unit gear housing on MerCruiser Alpha One outdrives
• Replaces multiple OEM and aftermarket part numbers for broad compatibility
• Suitable for both standard and counter-rotation configurations

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here's a guide to help you identify your engine's serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

This kit includes:

• 1 × Lower Unit Gear Housing Seal Kit

Note: The package contains all the parts shown in the product image.

Installation Guide

1. Disconnect the battery and remove the sterndrive unit from the boat following manufacturer procedures.
2. Drain all gear oil from the lower unit into an appropriate container. Inspect for metal shavings or water contamination.
3. Separate the lower gear housing from the upper driveshaft housing by removing the retaining bolts.
4. Remove the old seals from the driveshaft and propeller shaft areas using seal removal tools. Clean all sealing surfaces thoroughly.
5. Inspect the gear housing bore and shaft surfaces for scoring, corrosion, or damage; repair or replace components as needed.
6. Lubricate the new seals with gear oil or assembly grease. Install each seal in the correct orientation using a seal driver or appropriately sized socket.
7. Reassemble the lower unit to the driveshaft housing, ensuring proper alignment of the water tube and shift components.
8. Torque all fasteners to MerCruiser specifications in a crossing pattern to ensure even clamping.
9. Refill the lower unit with the manufacturer-recommended gear oil through the fill plug until it reaches the vent hole.
10. Install and torque the vent and fill plugs. Wipe away excess oil.
11. Reinstall the sterndrive unit on the boat and reconnect all cables and hoses.
12. Run the engine in a test tank or on-water to verify proper operation and check for leaks around all seals.

Troubleshooting & FAQ

Q: How do I confirm this seal kit fits my MerCruiser outdrive?
A: Check your sterndrive model and year against the compatibility table above. This kit fits Alpha One Gen 1 units from 1964–1989 (IA, IB, IC, EZ Shift, R, MR, Alpha 1). Cross-reference your existing part number (26-33144A2, 26-33144A1, 26-89238A1, or aftermarket 18-2652, 87510, 9-74304) to ensure a match.

Q: What are the signs that my lower unit seals need replacement?
A: Common symptoms include gear oil leaking from the lower unit, water in the gear oil (milky appearance), difficulty shifting gears, or unusual noise during operation. If you notice any of these, inspect and replace the seals promptly to prevent further damage.

Q: How often should I replace the lower unit seals?
A: Replace seals whenever you disassemble the lower unit for service, if you observe leaks, or as part of routine maintenance every 2–3 years depending on usage. Boats in saltwater or heavy-use environments may require more frequent inspection and replacement.

Q: Can I install this seal kit myself, or do I need a professional?
A: Installation requires mechanical knowledge, specialized tools (seal drivers, torque wrench), and familiarity with MerCruiser sterndrive service procedures. While experienced DIYers can perform this work, professional installation is recommended to ensure proper alignment, torque specifications, and seal integrity.

Q: Is this an OEM or aftermarket seal kit?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.