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 18-25 HP 2-Stroke outboard motors (1958–1978). It provides all the necessary seals and gaskets to rebuild your gearcase and prevent water intrusion or oil leaks, restoring the reliability of your engine.

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 Method: Comprehensive repair and replacement of lower unit seals.
• Core Components: Includes all essential seals, gaskets, and O-rings for the gearcase.
• Warranty: This JSProxam kit comes with a 90-day warranty.

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

This kit contains the following components:

• 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

A typical installation involves the following steps. Professional installation is recommended.

1. Drain Gear Lube: Position a drain pan under the lower unit. Remove the upper and lower gearcase drain/fill screws and let the old lubricant drain completely.
2. Remove Lower Unit: Disconnect the shift linkage (if applicable) and unbolt the lower unit from the engine's mid-section.
3. Disassemble Housing: Remove the propeller, followed by the propeller shaft bearing carrier housing, to access the primary seals.
4. Replace Prop Shaft Seals: Carefully extract the old seals and O-rings from the bearing carrier. Thoroughly clean the housing surfaces before pressing in the new seals.
5. Replace Driveshaft Seals: Remove the water pump assembly to access and replace the upper driveshaft seals and O-rings.
6. Reassemble: Reinstall the bearing carrier and water pump assemblies, ensuring all components are correctly seated and torqued.
7. Reattach Lower Unit: Mount the lower unit back onto the engine mid-section, reconnect the shift linkage, and tighten all bolts to the manufacturer's specified torque.
8. Refill with Lube: Using a gear lube pump, fill the gearcase from the bottom drain hole until fresh lubricant emerges from the upper vent hole. Install the new washers and screws.

Troubleshooting & FAQ

How can I be sure this seal kit fits my Johnson/Evinrude engine?
First, verify your engine's horsepower and year fall within the specified range (18-25 HP, 1958-1978). Next, compare your existing part numbers to the cross-reference list, which includes Sierra 18-2684 and GLM 87606. Using the compatibility table and part numbers is the most reliable way to ensure a correct fit.

What are the common signs that my lower unit seals are failing?
The most common sign is milky or creamy-looking gear lube, which indicates water has mixed with the oil. You may also notice gear oil leaking from the propeller shaft area or from behind the water pump housing. Failure to address this can lead to catastrophic gear failure.

How often should I replace lower unit seals?
It is best practice to inspect your gear lube annually. We recommend replacing the lower unit seals every 3-5 years as preventative maintenance, or immediately if you discover any signs of water intrusion or oil leaks.

OEM vs. Aftermarket?
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.

How fast do you ship and how much does it cost?
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.

What is your warranty and return policy?
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.