Lower Unit Seal Kit – Fits Johnson Evinrude 85-125 HP
This lower unit gearcase seal kit is designed for Johnson/Evinrude 85, 100, and 125 HP outboard models (1971–1972) equipped with a large prop shaft. It provides the necessary components to restore seal integrity and prevent water intrusion or oil leaks in the gearcase.
This kit is a direct replacement for several OEM and aftermarket part numbers, including Sierra 18-2691, GLM 87611, and Mallory 9-74114.
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Complete Kit: Includes all necessary oil seals, O-rings, and gaskets for a lower unit overhaul.
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Direct Replacement: Engineered to match OEM specifications for a precise fit and reliable function.
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Application: Specifically designed for select 1971–1972 Johnson/Evinrude outboard motors.
Part Number Cross-Reference
Use this table to confirm equivalent part numbers across OEM and aftermarket brands.
| Brand |
Part Number |
| Sierra |
18-2691 |
| GLM |
87611 |
| Mallory |
9-74114 |
| QuickMarine |
18-2691 |
| UanofCn |
18-2691 |
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.
| Brand |
Model |
Rated HP |
Prop Shaft |
Years |
OEM Part No. |
| Johnson/Evinrude |
Johnson/Evinrude |
85 |
Large Prop Shaft |
1971-1972 |
18-2691 |
| Johnson/Evinrude |
Johnson/Evinrude |
100 |
Large Prop Shaft |
1971-1972 |
18-2691 |
| Johnson/Evinrude |
Johnson/Evinrude |
125 |
Large Prop Shaft |
1971-1972 |
18-2691 |
Technical Specifications
| Specification |
Value |
| Product Type |
Lower Unit Gearcase Seal Kit |
| Installation |
Direct replacement |
| Package Contents |
Oil seals, O-rings, Gaskets |
| Dimensions |
150 × 100 × 30 mm (5.91 × 3.94 × 1.18 inches) [package dimensions] |
| Weight |
0.08 kg (2.82 ounces) |
| Position |
Lower unit |
| Application |
Marine outboard motors |
| Warranty |
Manufacturer warranty (details vary by brand) |
Package Contents
- Oil Seals (Various sizes)
- O-rings (Various sizes)
- Gaskets (Various types)
Installation Guide
- Ensure the engine is off and securely positioned in a stand or on the vessel.
- Drain the gearcase oil completely by removing the drain and vent plugs.
- Remove the propeller assembly from the propshaft.
- Unbolt and carefully separate the entire gearcase (lower unit) from the outboard's midsection.
- Disassemble the lower unit to access the propeller shaft bearing housing, driveshaft, and shift shaft seals. Keep parts organized.
- Carefully remove all old seals, O-rings, and gaskets. Clean the component surfaces of any sealant, corrosion, or debris.
- Compare the new seals from the kit to the old parts to confirm correct sizing and placement.
- Lightly lubricate the new seals with marine grease before carefully pressing them into place. Ensure they are seated correctly.
- Install the new gaskets and O-rings during reassembly.
- Reassemble the lower unit, torquing all bolts to the manufacturer's specified values.
- Refill the gearcase with the correct grade and amount of fresh marine gear lube.
- Check for any leaks around the drain plugs, shafts, and seams before operating the engine under load.
Troubleshooting & FAQ
Q: How do I confirm this seal kit fits my Johnson/Evinrude engine?
A: This kit is specifically for 85-125 HP models from 1971-1972 with a large prop shaft. The best way to confirm fitment is to cross-reference your original part number with the ones listed, such as Sierra 18-2691, GLM 87611, or Mallory 9-74114.
Q: What are the signs that my lower unit seals are failing?
A: The most common symptoms are milky or water-contaminated gear oil (which looks like coffee with cream), visible oil leaks from the propeller shaft area, or a distinct burning smell coming from the gearcase after operation.
Q: How often should I replace the lower unit seals?
A: There is no fixed replacement interval. Seals should be replaced whenever the lower unit is serviced, if you notice any signs of leaks or water intrusion, or as a part of preventative maintenance on older engines.
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?
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Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
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Fast Global Shipping: Free delivery worldwide in 5–15 days.
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Direct from Manufacturer: Competitive pricing without compromising quality.