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.
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Installation Method: Direct replacement design for a straightforward installation.
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Rotational Compatibility: Fully compatible with both right-hand and left-hand rotation gearcases.
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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.
Brand |
Part Number |
Mercury |
8M0088081 |
Mercury |
46-8M0088081 |
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.
Brand |
Model |
Rated HP |
Stroke |
OEM Part No. |
Notes |
Mercury |
Standard |
65 |
4-Stroke |
8M0088081 |
|
Mercury |
Standard |
75 |
4-Stroke |
8M0088081 |
|
Mercury |
Standard |
80 |
4-Stroke |
8M0088081 |
International model |
Mercury |
Standard |
90 |
4-Stroke |
8M0088081 |
|
Mercury |
Standard |
100 |
4-Stroke |
8M0088081 |
International model |
Mercury |
Standard |
115 |
4-Stroke |
8M0088081 |
|
Mercury |
115 Pro XS |
115 |
4-Stroke |
8M0088081 |
|
Mercury |
SeaPro |
75 |
4-Stroke |
8M0088081 |
Command Thrust model |
Mercury |
SeaPro |
90 |
4-Stroke |
8M0088081 |
Command Thrust model |
Mercury |
SeaPro |
115 |
4-Stroke |
8M0088081 |
Command Thrust model |
Mercury |
Command Thrust |
65-115 |
4-Stroke |
8M0088081 |
Different gearcase lubricant capacity |
Technical Specifications
Specification |
Value |
Product Type |
Gearcase Seal Kit |
Installation |
Direct replacement |
Other Technical Attributes |
Compatible with both right-hand and left-hand rotation gearcases |
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
- Position the outboard securely in a vertical position and place a drain pan under the gearcase.
- Remove the upper and lower gear lubricant drain screws and drain the lubricant completely.
- Remove the propeller assembly.
- Remove the bolts securing the gearcase to the driveshaft housing and carefully separate the two assemblies.
- Following your service manual, disassemble the gearcase to access the driveshaft, prop shaft, and shift shaft seals.
- Carefully remove the old seals, taking note of their orientation. Clean the seal seating surfaces meticulously.
- Install the new seals from the kit using appropriate seal drivers to ensure they are seated correctly and without damage.
- Lubricate the new seals with marine grease before reassembling the shafts and carriers.
- Reassemble all gearcase components in the reverse order of disassembly, torquing all fasteners to manufacturer specifications.
- Reattach the gearcase to the engine, ensuring the water tube and shift shaft are properly aligned.
- Refill the gearcase with the correct amount and type of fresh marine gear lubricant.
- 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?
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Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
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Fast Global Shipping: Free delivery worldwide in 5–15 days.
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Direct from Manufacturer: Competitive pricing without compromising quality.