Lower Unit Seal Kit – Fits Johnson/Evinrude 18-25 HP (Replaces 18-2684, 87606, 9-74105)

Lower Unit Seal Kit – Fits Johnson/Evinrude 18-25 HP (Replaces 18-2684, 87606, 9-74105)

This lower unit seal kit is designed for Johnson/Evinrude 18 HP, 20 HP, and 25 HP 2-stroke outboard motors manufactured between 1958 and 1978. It provides all the necessary seals and gaskets to rebuild and reseal your lower unit gearcase, preventing water intrusion and oil leaks.

This kit serves as a direct replacement for several aftermarket part numbers, including Sierra 18-2684, GLM 87606, Mallory 9-74105, QuickMarine 18-2684, JSProxam 18-2684, Boatpartstore 18-2684, and EMP/Wholesale Marine 26-01728.

• Installation Type: Complete repair and replacement of lower unit seals.
• Function: Restores gearcase integrity by replacing all critical seals and gaskets.
• Warranty: This kit is backed by a 90-day warranty (JSProxam).

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 Johnson/Evinrude owners, here’s a guide to help you identify your engine’s serial/model: Johnson/Evinrude Serial Number Guide.

Technical Specifications

Package Contents

• 1 x Shift Rod Gasket (18-0882)
• 1 x Oil Seal (18-2031)
• 1 x Oil Seal (18-2032)
• 1 x Seal Kits (18-2534)
• 2 x Drain/Fill Plug Washer (18-4248)
• 1 x O-Ring (18-7100)
• 1 x O-Ring (18-7120)

Installation Guide

1. Preparation: Drain the gearcase lubricant completely. Secure the outboard motor in a stable, upright position.
2. Lower Unit Removal: Unbolt and carefully detach the lower unit (gearcase) from the engine's midsection. You may need to disconnect the shift linkage.
3. Bearing Carrier Disassembly: Remove the propeller shaft bearing carrier. This often requires a special puller tool.
4. Old Seal Removal: Identify and carefully pry out the old oil seals, gaskets, and O-rings from the housing and driveshaft areas. Avoid scratching the metal surfaces.
5. Cleaning and Inspection: Thoroughly clean all sealing surfaces, removing any old adhesive, corrosion, or debris. Inspect components for excessive wear or damage.
6. New Seal Installation: Lubricate the new seals and O-rings with marine grease. Press them into place evenly, ensuring they are fully seated and square in their bores.
7. Reassembly: Reassemble the components in the reverse order of disassembly. Ensure correct alignment of all parts.
8. Lower Unit Reinstallation: Reattach the lower unit to the motor, making sure the driveshaft spline, water tube, and shift rod are correctly aligned.
9. Refill with Lubricant: Fill the gearcase with the manufacturer-recommended lower unit lubricant through the bottom fill hole until it flows out the upper vent hole.
10. Leak Check: Install both drain/vent plug screws with new washers. Check for any signs of leakage around the seals before operating the engine.

Troubleshooting & FAQ

Q: How can I be sure this seal kit fits my specific Johnson/Evinrude motor?
A: This kit is designed for the 18, 20, and 25 HP models listed in the compatibility table for years 1958-1978. Always verify your engine's horsepower and year range before ordering. You can also use the cross-reference table to match your existing part number if you are replacing another aftermarket kit.

Q: What are common signs that my lower unit seals are failing?
A: The most common indicator is milky or creamy-looking gear lube when you drain it, which signals water intrusion. Other signs include visible oil leaks around the propeller shaft or driveshaft, or a recurring need to top off the gear oil.

Q: How often should lower unit seals be replaced?
A: We recommend replacing lower unit seals as part of regular preventative maintenance every 2-3 seasons or 200-300 hours of use. You should replace them immediately if you discover any signs of water intrusion or oil leakage.

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.