26-816575A5 Seal Kit Gearcase for Mercury 225-300XS DFI EFI 3.0L 2.5L XS SportMaster | JLM Marine

26-816575A5 Seal Kit Gearcase for Mercury 225-300XS DFI EFI 3.0L 2.5L XS SportMaster

This premium gearcase seal kit is engineered for Mercury 225-300XS DFI EFI 3.0L and 2.5L XS SportMaster outboard motors. Designed to restore lower unit integrity and prevent fluid leaks, this complete seal kit ensures reliable performance and extended service life for high-performance Mercury engines.

This aftermarket replacement directly crosses to Mercury Marine 26-816575A5, Sierra 18-2642, GLM 87513, and Mallory 9-74209. Each component is meticulously selected to meet OE specifications, guaranteeing a seamless fit and dependable operation.

• Complete lower unit seal kit with all necessary seals and gaskets
• Precision-engineered for Mercury high-performance outboards
• Direct OEM-equivalent replacement for multiple part numbers

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

Your kit includes:

• 1 × Lower Unit Seal Kit (all seals and gaskets as shown in product images)

Installation Guide

1. Disconnect the battery and remove the propeller for safe access to the lower unit.
2. Drain all gear oil from the lower unit into an appropriate container.
3. Remove the lower unit from the engine by loosening the mounting bolts and carefully separating it from the midsection.
4. Disassemble the lower unit housing, noting the position and orientation of all components for reassembly.
5. Remove all old seals, gaskets, and O-rings from the housing and shafts. Clean all mating surfaces thoroughly with a suitable solvent to remove residue and old sealant.
6. Inspect all gears, bearings, and shafts for wear or damage; replace any worn components as necessary.
7. Install the new seals and gaskets from the kit, ensuring proper orientation and seating. Lubricate seals lightly with gear oil to prevent damage during assembly.
8. Reassemble the lower unit housing, carefully aligning all shafts and components according to your service manual.
9. Reattach the lower unit to the midsection, torquing all mounting bolts to the manufacturer's specifications.
10. Refill the lower unit with the correct type and quantity of gear oil through the fill port, monitoring the vent until oil appears.
11. Reinstall the propeller and reconnect the battery.
12. Test the engine in water, checking for leaks and smooth operation before returning to full service.

Troubleshooting & FAQ

Q: How do I confirm this seal kit fits my Mercury outboard?
A: Check the compatibility table above for your engine model. Verify your OEM part number matches 26-816575A5, Sierra 18-2642, GLM 87513, or Mallory 9-74209. If uncertain, consult your engine's parts diagram or contact us with your serial number.

Q: How often should I replace the lower unit seals?
A: Replace seals whenever you perform lower unit service, rebuild the gearcase, or notice gear oil leaks or milky appearance (indicating water intrusion). Typical service intervals are every 100 hours or annually, whichever comes first.

Q: What are the signs that my gearcase seals are failing?
A: Common symptoms include gear oil leaking from the lower unit, milky or discolored gear oil, difficulty shifting gears, or unusual noises from the lower unit during operation.

Q: Can I reuse the old seals if they look okay?
A: No. Seals are designed for one-time use and lose their sealing ability once removed. Always install fresh seals during any lower unit service to prevent leaks and ensure proper protection.

Q: Do I need any special tools to install this seal kit?
A: Basic hand tools are sufficient for disassembly and reassembly. A seal driver set and torque wrench are recommended for proper installation and to meet factory specifications.

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.