Mercury Gearcase Seal Kit – Fits Mercury 65-115 HP Outboards (Replaces 8M0088080)

Mercury Gearcase Seal Kit – Fits Mercury 65-115 HP Outboards (Replaces 8M0088080)

This gearcase seal kit is designed for Mercury FourStroke and Pro XS 65-115 HP outboard engines (2004–present). It provides the essential components needed to service and reseal the lower unit, preventing water intrusion and oil leaks.

It serves as a direct replacement for Mercury OEM part number 8M0088080.

• Installation: Designed for a direct OEM replacement fit.
• Function: Restores gearcase integrity by replacing worn or damaged seals.
• Compatibility: Engineered for a wide range of Mercury 65, 75, 80, 90, 100, and 115 HP 4-Stroke models.

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 8M0088080)

Installation Guide

1. Ensure the engine is off and securely positioned. Turn off the battery switch or disconnect the battery.
2. Place a drain pan under the gearcase. Remove the lower drain/fill plug and the upper vent plug to drain the gear lube completely.
3. Remove the propeller, thrust washer, and any related hardware. Inspect for fishing line, which can damage seals.
4. Unbolt the gearcase from the outboard's driveshaft housing and carefully lower it.
5. Disassemble the gearcase as necessary to access the propeller shaft and driveshaft seals.
6. Carefully pry out the old seals and O-rings using a seal puller, being cautious not to damage the housing surfaces.
7. Thoroughly clean all sealing surfaces and component bores to remove any old adhesive or debris.
8. Lubricate the new seals with a light coat of 2-4-C grease and press them into place using a suitable driver until they are properly seated.
9. Reassemble all components in the reverse order of disassembly, ensuring correct alignment.
10. Torque all bolts and nuts to the manufacturer's recommended specifications.
11. Refill the gearcase with new, high-quality marine gear lubricant until it flows from the upper vent hole, then reinstall both plugs.
12. After a short period, check for any signs of oil leaks around the seals.

Troubleshooting & FAQ

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

A: This kit is designed for Mercury 65-115 HP FourStroke and Pro XS models from 2004 to the present. Please check the "Compatible Engine Models" table and cross-reference your engine's model and year. Verifying that your current part number is 8M0088080 is also a reliable method.

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

A: The most common sign is milky, gray, or water-contaminated gear lube when you drain it. Other indicators include visible oil leaks around the propeller shaft housing or a persistent smell of gear oil from the lower unit. Failure to address this can lead to catastrophic gear failure.

Q: Is everything I need for the job included in this kit?

A: This kit contains the primary seals, gaskets, and O-rings needed for a standard gearcase reseal. It does not include gear lubricant, sealant/adhesive, or specialized tools (like a seal puller or press) which may be required for the installation.

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.