8M0057716 Gearcase Seal Kit for Mercury 135HP 150HP EFI | JLM Marine

8M0057716 Gearcase Seal Kit for Mercury 135HP 150HP EFI | JLM Marine

This gearcase seal kit is engineered to fit Mercury 135HP and 150HP EFI outboard engines, providing comprehensive sealing components for the gear housing and driveshaft assembly. Designed for both standard and counter rotation applications, this kit ensures reliable performance across multiple Mercury models and serial number ranges.

This aftermarket replacement directly cross-references to OEM part number 8M0057716, offering a cost-effective solution for maintaining your lower unit's integrity and preventing water intrusion.

• Complete seal kit for Mercury EFI gearcase assemblies
• Fits both standard and counter rotation configurations
• Suitable for gear housing and driveshaft maintenance

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

This gearcase seal kit includes all necessary sealing components required for servicing the gear housing and driveshaft assembly on compatible Mercury EFI outboards.

Installation Guide

1. Preparation: Disconnect the battery and remove the lower unit from the outboard motor following your service manual's instructions.
2. Disassembly: Drain the gear oil completely and remove the propeller shaft assembly. Carefully extract the driveshaft and note the orientation of all components.
3. Seal Removal: Remove all old seals, O-rings, and gaskets from the gear housing and driveshaft using appropriate seal removal tools. Clean all sealing surfaces thoroughly with solvent and inspect for damage.
4. Surface Preparation: Ensure all mating surfaces are free of debris, corrosion, and old seal material. Use a plastic scraper to avoid damaging aluminum surfaces.
5. New Seal Installation: Lubricate new seals with marine-grade grease before installation. Install seals carefully using the appropriate driver or socket to avoid cocking or damage.
6. Reassembly: Reinstall the driveshaft, propeller shaft, and all components in reverse order. Torque all fasteners to manufacturer specifications.
7. Refill & Test: Refill the lower unit with the correct grade and quantity of gear oil. Reinstall the lower unit, check for leaks, and perform a water test to verify proper operation.

Troubleshooting & FAQ

Q: How do I confirm this seal kit fits my Mercury outboard?
A: Verify your engine's serial number against the compatibility table above. Mercury 135HP and 150HP EFI models with serial numbers 2B131942 & up (135HP), 1B905505 & up (150HP), and 2B139139 & up (150HP Sea Pro) are compatible. Cross-check with your parts diagram to ensure the component matches.

Q: How often should I replace the gearcase seals?
A: Replace gearcase seals whenever the lower unit is disassembled for service, or immediately if you notice milky gear oil (indicating water intrusion), oil leaks around the propeller shaft, or loss of gear oil level. Regular inspection during seasonal maintenance is recommended.

Q: What tools do I need to install this seal kit?
A: You'll need seal drivers or appropriately sized sockets, a seal puller or pick set, torque wrench, gear oil pump, marine-grade grease, and basic hand tools. A service manual for your specific model is highly recommended for torque specifications and assembly sequences.

Q: Can I use this kit on both standard and counter rotation lower units?
A: Yes, this seal kit is designed for both standard and counter rotation configurations on the compatible Mercury EFI models listed. The sealing components are identical for both rotation types.

Q: What are signs of failing gearcase seals?
A: Common symptoms include milky or contaminated gear oil, visible oil leaks near the propeller or driveshaft, loss of gear oil between services, overheating of the lower unit, or unusual noise during operation. Address these issues immediately to prevent bearing and gear damage.

Q: Is this an OEM part or 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.