18-2691 Lower Unit Gearcase Seal Kit for Evinrude Johnson | JLM Marine

Lower Unit Gearcase Seal Kit for Evinrude Johnson 2-Stroke Outboards – 18-2691

This lower unit gearcase seal kit is designed for Evinrude Johnson 2-stroke outboards with 85 HP, 100 HP, and 125 HP ratings (large prop shaft models) manufactured between 1971–1972. It provides a complete seal replacement solution for routine maintenance or gearcase overhaul.

This kit directly replaces OEM part number 18-2691, ensuring proper fitment and reliable performance for compatible lower units.

• Contains all essential seals, gaskets, O-rings, and washers for lower gearcase assembly
• Fits select large prop shaft models only – verify your engine configuration before ordering
• Includes both oil seals and multiple O-rings for complete lower unit service

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 lower unit seal kit includes the following components:

• 18-2874 – Solenoid Cover Gasket (OEM 314876) – Qty: 1
• 18-4248 – Washer (OEM 311598) – Qty: 2
• 18-7109 – O-Ring (OEM 317178) – Qty: 4
• 18-7127 – O-Ring (OEM 313446) – Qty: 1
• 18-7130 – O-Ring (OEM 314728) – Qty: 1
• 18-2001 – Oil Seal (OEM 330137) – Qty: 2
• 18-2059 – Oil Seal (OEM 321466) – Qty: 2

Note: The package contains all the parts shown in the product images.

Installation Guide

1. Disconnect the fuel line and remove the lower unit from the outboard following your service manual instructions. Drain all gear oil completely.
2. Remove the propeller, prop shaft, and associated hardware. Clean all mating surfaces thoroughly to remove old gasket material and debris.
3. Inspect the prop shaft and gearcase housing for wear, scoring, or damage that may compromise seal performance.
4. Remove old oil seals, O-rings, gaskets, and washers from the gearcase. Note the orientation and position of each component.
5. Install new oil seals (18-2001 and 18-2059) using a seal driver or appropriate socket to seat them evenly without cocking.
6. Lubricate all new O-rings (18-7109, 18-7127, 18-7130) with gear oil and install in their respective grooves.
7. Place new washers (18-4248) in their designated locations on the prop shaft assembly.
8. Install the solenoid cover gasket (18-2874) ensuring proper alignment with bolt holes.
9. Reassemble the prop shaft into the gearcase, taking care not to damage newly installed seals.
10. Reinstall the lower unit onto the outboard and torque all fasteners to manufacturer specifications.
11. Refill the gearcase with the correct type and quantity of gear oil per your service manual. Check for proper oil level at both drain and vent plugs.
12. Run the engine and inspect for leaks around all seal areas before returning to regular operation.

Troubleshooting & FAQ

Q: How do I confirm this seal kit fits my specific outboard?
A: This kit fits only 1971–1972 Evinrude/Johnson 85, 100, and 125 HP 2-stroke models with a large prop shaft. Verify your engine year, HP rating, and prop shaft diameter against your service manual or measure your existing shaft before ordering.

Q: Does this kit include everything needed for a complete lower unit seal replacement?
A: Yes, this kit contains all seals, O-rings, gaskets, and washers required for lower gearcase service as listed in the package contents. You will need gear oil separately to refill the unit after installation.

Q: How often should I replace lower unit seals?
A: Replace seals whenever you notice gear oil leaks, milky oil (water intrusion), or during major lower unit service. Many mechanics recommend inspection every 100 hours of operation or annually, whichever comes first.

Q: What are the signs that my lower unit seals are failing?
A: Common symptoms include visible gear oil leaks around the prop shaft, water mixed with gear oil (appearing milky), difficulty shifting, or unusual noise from the gearcase. Address seal failure promptly to prevent internal damage.

Q: Can I reuse old seals and O-rings if they look okay?
A: No. Seals and O-rings lose elasticity and sealing capability once removed, even if they appear intact. Always install new components during gearcase service to ensure reliable sealing.

Q: Is this an OEM part or aftermarket replacement?
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.