Gearcase Seal Kit – Fits Mercury/Mariner 150 HP EFI FourStroke Outboards (Replaces 8M0057716)

Gearcase Seal Kit – Fits Mercury/Mariner 150 HP EFI FourStroke Outboards (Replaces 8M0057716)

This gearcase seal kit is designed for Mercury/Mariner 150 HP EFI FourStroke outboard engines from 2007 and newer (serial number 1B905505 and up). It provides all the necessary seals and gaskets to service the lower unit and prevent water intrusion.

This kit is a direct replacement for Mercury OEM part number 8M0057716, GLM Marine 87527, and Recmar REC8M0057716, ensuring proper fit and function.

• Installation Location: Gaskets and seals for the gearcase/lower unit.
• Durable Construction: Made from high-quality, corrosion-resistant materials for a long service life.
• Watertight Protection: Creates a reliable, watertight seal to protect internal gearcase components from water damage.

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

• SEAL (830749)
• SEAL, Oil (89238)
• O-RING, (2.175 x .103) (896523)
• O-RING, (.987 x .103) (45258)
• O-RING, (.796 x .139) (21836)
• SEAL, Oil (816464 1)

Installation Guide

1. Drain Oil: Drain the gearcase oil completely by removing the drain and vent screws.
2. Remove Lower Unit: Remove the propeller and unbolt the lower unit from the outboard engine.
3. Disassemble: Carefully disassemble the gearcase, including the bearing carrier and driveshaft components, noting the orientation of each part.
4. Remove Old Seals: Using appropriate tools, remove all old seals, gaskets, and O-rings that are being replaced by the new kit.
5. Clean Surfaces: Thoroughly clean all mating surfaces, ensuring they are free of old sealant, corrosion, and debris.
6. Install New Seals: Lightly lubricate the new seals and O-rings with marine grease and carefully press them into place.
7. Reassemble Gearcase: Reassemble the gearcase components in the reverse order of disassembly.
8. Reinstall Lower Unit: Reattach the lower unit to the outboard and install the propeller.
9. Refill with Oil: Refill the gearcase with manufacturer-recommended gear lube to the correct level.
10. Check for Leaks: Before operating the boat, check for any signs of oil leaks around the seals.

Troubleshooting & FAQ

Q: How do I confirm this fits my engine?

A: This kit is designed for Mercury/Mariner 150 HP EFI FourStroke models from 2007 and newer (serial number 1B905505 and up). Please check the "Compatible Engine Models" table and use the linked serial number guide to verify your exact model before purchasing.

Q: What are the signs I need to replace my gearcase seals?

A: The most common sign is milky or water-contaminated gear lube when you drain it. Other signs include visible oil leaks around the propeller shaft or driveshaft, or if you notice a loss of gearcase pressure during a pressure test.

Q: How often should I replace gearcase seals?

A: It is good practice to inspect seals during regular lower unit service (e.g., water pump replacement). We recommend replacing them every 2-3 years as preventative maintenance or anytime the lower unit is disassembled for service to ensure a reliable seal.

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.