Gearcase Seal Kit – Fits Mercury 65-115 HP Outboard Engines (Replaces 8M0088081)

Gearcase Seal Kit – Fits Mercury 65-115 HP Outboard Engines (Replaces 8M0088081)

This gearcase seal kit is designed for Mercury 65-115 HP 4-Stroke outboard engines, including both standard and Command Thrust models. It provides a reliable solution for maintaining and repairing your lower unit to prevent water intrusion and oil leaks.

This kit is a direct replacement for Mercury Marine part numbers 8M0088081 and 46-8M0088081, ensuring compatibility and performance equivalent to the original equipment.

• Installation Method: Direct replacement design for a straightforward installation.
• Rotational Compatibility: Fully compatible with both right-hand and left-hand rotation gearcases.
• Core Components: Includes all necessary seals for a complete lower unit service.

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 Gearcase Seal Kit (Replaces 8M0088081)

Note: Gearcase lubricant capacity varies by specific model.
• Standard gearcase: 800 ml (27.1 fl oz)
• Command Thrust Right-hand rotation: 810 ml (27.4 fl oz)
• Command Thrust Left-hand rotation: 790 ml (26.7 fl oz)

Installation Guide

1. Position the outboard securely in a vertical position and place a drain pan under the gearcase.
2. Remove the upper and lower gear lubricant drain screws and drain the lubricant completely.
3. Remove the propeller assembly.
4. Remove the bolts securing the gearcase to the driveshaft housing and carefully separate the two assemblies.
5. Following your service manual, disassemble the gearcase to access the driveshaft, prop shaft, and shift shaft seals.
6. Carefully remove the old seals, taking note of their orientation. Clean the seal seating surfaces meticulously.
7. Install the new seals from the kit using appropriate seal drivers to ensure they are seated correctly and without damage.
8. Lubricate the new seals with marine grease before reassembling the shafts and carriers.
9. Reassemble all gearcase components in the reverse order of disassembly, torquing all fasteners to manufacturer specifications.
10. Reattach the gearcase to the engine, ensuring the water tube and shift shaft are properly aligned.
11. Refill the gearcase with the correct amount and type of fresh marine gear lubricant.
12. Install new gaskets on the drain screws and tighten them securely. Check for any leaks before reinstalling the propeller.

Troubleshooting & FAQ

Q: How do I know if this seal kit will fit my Mercury engine?

A: This kit is designed for Mercury 65-115 HP 4-Stroke outboards, including standard and Command Thrust models. Please check the "Compatible Engine Models" table and cross-reference your OEM part number (8M0088081 or 46-8M0088081) to ensure a perfect fit.

Q: What are the common signs that my gearcase seals are failing?

A: Common signs include milky or water-contaminated gear lube, visible oil leaks around the propeller shaft or driveshaft, or an unexplained loss of gear lubricant.

Q: Is there a difference in installation for standard and Command Thrust models?

A: The seal installation process is the same, but the gearcase lubricant capacity differs. Standard models require 800 ml, while Command Thrust models require 810 ml (right-hand rotation) or 790 ml (left-hand rotation). Always verify the correct capacity for your specific gearcase.

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.