Lower Unit Seal Kit – Fits Honda BF75/BF90 Outboard Motors (Replaces 18-8366, 91251-ZW1-003, 91252-ZW1-003, 91253-ZW1-003, 91254-ZW1-003, 91255-ZW1-003)

Lower Unit Seal Kit – Fits Honda BF75/BF90 Outboard Motors

This lower unit seal kit is designed for Honda 75-90 HP 4-stroke outboard motors, covering models from 1997-1998 and later. It provides the essential seals needed to service the gearcase and prevent water intrusion or oil leaks.

This kit serves as a direct replacement for Sierra Marine part number 18-8366 and contains individual seals that replace Honda OEM parts 91251-ZW1-003, 91252-ZW1-003, 91253-ZW1-003, 91254-ZW1-003, and 91255-ZW1-003.

• Complete Seal Replacement: Includes all necessary seals for a standard lower unit service on compatible Honda models.
• Direct Fit: Engineered to match OEM specifications for a reliable, leak-free installation.
• Prevents Contamination: Restores the integrity of your gearcase, protecting internal components from damaging water intrusion.

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.

Technical Specifications

Package Contents

• 1 x Driveshaft Seal (Replaces 91251-ZW1-003)
• 1 x Propeller Shaft Seal, Inner (Replaces 91252-ZW1-003)
• 1 x Shift Shaft Seal (Replaces 91253-ZW1-003)
• 1 x Driveshaft Oil Seal (Replaces 91254-ZW1-003)
• 1 x Propeller Shaft Seal, Outer (Replaces 91255-ZW1-003)

Installation Guide

1. Begin by draining the gearcase oil into a suitable container.
2. Remove the lower unit assembly from the outboard motor's driveshaft housing.
3. Carefully extract the old seals from the driveshaft, propeller shaft, and shift shaft cavities. Pay close attention to their original orientation.
4. Thoroughly clean the seal seating surfaces inside the gearcase, removing any old sealant or debris.
5. Lightly lubricate the new seals with marine-grade grease before installation.
6. Using a socket or a professional seal driver, press the new seals into place until they are fully and evenly seated. Ensure the seal orientation is correct.
7. Reassemble the lower unit components and re-install the unit onto the motor.
8. Refill the gearcase with new lower unit lubricant to the level specified by the manufacturer.
9. Before returning to service, check for any signs of oil leakage around the newly installed seals.

Troubleshooting & FAQ

Q: How do I confirm this seal kit fits my Honda engine?
A: This kit is specifically designed for Honda BF75 (75 HP) and BF90 (90 HP) 4-stroke models manufactured in 1997-1998 and later. To guarantee fitment, please cross-reference your engine's model and year with the compatibility chart. You can also verify by matching the OEM part numbers on your old seals to those listed in our cross-reference table, such as Sierra 18-8366 or the individual Honda numbers (e.g., 91251-ZW1-003).

Q: What are the common signs that my lower unit seals are failing?
A: The most common indicator of a failed seal is finding milky or creamy-colored gear lube when you drain it, which signals water has mixed with the oil. You might also notice visible oil leaking from around the propeller shaft or the driveshaft area. Regular inspection of your gear lube is the best way to catch a bad seal early.

Q: How often should I replace my lower unit seals?
A: It is recommended to inspect lower unit seals annually during routine maintenance. As a preventative measure, it's good practice to replace them every couple of boating seasons or immediately if you detect any signs of leakage or water contamination in the gear lube.

Q: Is this an OEM part or an aftermarket one?
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.