Lower Unit Seal Kit – Fits Mercury/Mariner Outboard 30-125 HP (Replaces 26-43035A4)

Lower Unit Seal Kit – Fits Mercury/Mariner Outboard 30-125 HP (Replaces 26-43035A4)

This lower unit seal kit is designed for a wide range of Mercury/Mariner 30-125 HP 2-stroke and 4-stroke outboards (1991-2010). It is compatible with lower units featuring either a 3-jaw or 6-jaw reverse clutch. This kit fits USA serial numbers 0B209468 and newer, and Belgium serial numbers 9523034 and newer.

This kit directly replaces Mercury OEM part numbers 26-43035A4, 26-43035A3, 26-43035A2, and 26-43035A1. It also serves as an aftermarket replacement for Sierra 18-2626, GLM 87590, and Mallory 9-74200.

• Installation: Designed for direct replacement of the original seals.
• Compatibility: Fits lower units with either 3-jaw or 6-jaw reverse clutches.
• Complete Kit: Includes all necessary seals and gaskets for a lower unit rebuild.

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

• 1 x Lower Unit Seal Kit (Replaces 26-43035A4), including all necessary seals and gaskets for service.

Installation Guide

1. Drain the gearcase oil completely into a suitable container.
2. Remove the propeller and then unbolt and detach the lower unit from the outboard's driveshaft housing.
3. Carefully disassemble the gearcase, removing the bearing carrier and old seals. Take photos to remember the assembly order.
4. Thoroughly clean all components and mating surfaces, removing any old sealant or gasket residue.
5. Lubricate the new seals with marine grease and install them into their respective bores, ensuring they are seated properly and facing the correct direction.
6. Install the new gaskets and reassemble the lower unit components.
7. Torque all bolts to the manufacturer's specified values.
8. Reinstall the lower unit onto the outboard and attach the propeller.
9. Refill the gearcase with the correct type and amount of fresh gear lube before operation.

Troubleshooting & FAQ

Q: How do I confirm this seal kit fits my specific Mercury outboard?

A: Check your engine's serial number. This kit is confirmed to fit USA models 0B209468 and newer and Belgium models 9523034 and newer. It is designed for the wide range of 30-125 HP 2-stroke and 4-stroke models listed in our compatibility table.

Q: What are the signs that my lower unit seals are failing?

A: Common signs of seal failure include milky or watery gear oil, which indicates water intrusion. You may also notice visible oil leaks around the propeller shaft or driveshaft, or find a metallic sheen in the drained oil, suggesting wear from poor lubrication.

Q: Is this kit compatible with both 3-jaw and 6-jaw clutches?

A: Yes. This kit is specifically designed to work for lower units equipped with either the 3-jaw or 6-jaw reverse clutch, making it a versatile replacement for the specified HP and year range.

Q: OEM vs. Aftermarket?

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.