Lower Unit Seal Kit – Fits Johnson/Evinrude 85-125 HP (Replaces 18-2691, GLM 87611, Mallory 9-74114)
Lower Unit Seal Kit – Fits Johnson/Evinrude 85-125 HP (Replaces 18-2691, GLM 87611, Mallory 9-74114) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
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Lower Unit Seal Kit – Fits Johnson/Evinrude 85-125 HP (Replaces 18-...
Lower Unit Seal Kit – Fits Johnson/Evinrude 85-125 HP (Replaces 18-2691, GLM 87611, Mallory 9-74114) is backordered and will ship as soon as it is back in stock.
Product Details
This Lower Unit Seal Kit provides the necessary components to restore the gearcase on Johnson and Evinrude 85-125 HP outboard motors with a large prop shaft manufactured between 1971–1972. It is engineered to stop leaks and protect internal gears from water intrusion.
The kit serves as a direct replacement for several part numbers, including Sierra 18-2691, GLM 87611, and Mallory 9-74114, ensuring broad compatibility for the specified engine models.
- Installation: Designed for a direct replacement fit.
- Application: Suitable for marine outboard motor lower units.
- Contents: Includes essential oil seals, O-rings, and gaskets required for a typical reseal job.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Sierra | 18-2691 |
| GLM | 87611 |
| Mallory | 9-74114 |
| QuickMarine | 18-2691 |
| UanofCn | 18-2691 |
Engine & Model Compatibility
Confirm your engine model and year in the table below to ensure accurate fitment.
| Brand | Rated HP | Prop Shaft | Years | OEM Part No. |
|---|---|---|---|---|
| Johnson/Evinrude | 85 HP | Large Prop Shaft | 1971–1972 | 18-2691 |
| Johnson/Evinrude | 100 HP | Large Prop Shaft | 1971–1972 | 18-2691 |
| Johnson/Evinrude | 125 HP | Large Prop Shaft | 1971–1972 | 18-2691 |
Technical Specs
- Product Type
- Lower Unit Gearcase Seal Kit
- Installation
- Direct replacement
- Position
- Lower unit
- Application
- Marine outboard motors
- Package Contents
- Oil seals, O-rings, Gaskets
- Package Dimensions
- 150 × 100 × 30 mm (5.91 × 3.94 × 1.18 inches)
- Weight
- 0.08 kg (2.82 ounces)
- Warranty
- Manufacturer warranty (details vary by brand)
What’s in the Box
- Oil Seals (Various sizes)
- O-rings (Various sizes)
- Gaskets (Various types)
Installation Notes
- Drain the lower unit by removing the upper and lower gear oil drain screws.
- Remove the propeller assembly from the prop shaft.
- Unbolt and carefully remove the gearcase bearing carrier housing.
- Take note of the orientation and position of all old seals and O-rings before removing them.
- Thoroughly clean all component surfaces and seal grooves, ensuring they are free of old sealant, dirt, and corrosion.
- Lightly lubricate the new seals and O-rings with marine grease before installation to ensure a smooth fit and proper sealing.
- Carefully press the new seals into place, ensuring they are seated evenly and correctly.
- Reassemble all components in reverse order of disassembly.
- Refill the lower unit with the manufacturer-specified gear lube.
- For best results, perform a vacuum and pressure test on the gearcase to confirm there are no leaks before operating the outboard.
Troubleshooting & FAQ
How do I know if this kit fits my specific engine model?
This kit is designed for Johnson and Evinrude 85, 100, and 125 HP outboards with a large prop shaft made in 1971 and 1972. Cross-reference your existing part number with those listed in the Part Number Matrix (e.g., Sierra 18-2691, GLM 87611) to ensure compatibility.
What are the common signs of a failing lower unit seal?
The most common symptom is milky or creamy-looking gear lube, which indicates water intrusion. You may also notice gear oil leaking from the prop shaft area or around the drain/fill screw seals.
How often should lower unit seals be replaced?
There is no fixed replacement interval, but it's good practice to inspect the gear lube for water at every oil change. Seals should be replaced immediately if a leak is detected, or as preventative maintenance on older engines, especially those used in saltwater.
Does this kit include all the seals for the entire lower unit?
This kit contains the primary seals, gaskets, and O-rings for the lower unit gearcase area, including the prop shaft and bearing carrier. However, it may not include every possible seal, such as those for the water pump or shift shaft, which are often sold in separate kits.
Is professional installation necessary?
While DIY installation is possible for mechanically inclined individuals with the correct tools (like a bearing carrier puller), we recommend professional installation to ensure all seals are seated correctly and a pressure test can be performed to guarantee a leak-free repair.
What's the difference between aftermarket and OEM parts?
This listing is for an aftermarket replacement, not an original equipment manufacturer (OEM) part. It is engineered to meet or exceed OEM specifications using comparable materials and is manufactured in modern, quality-controlled facilities. It offers a cost-effective alternative without sacrificing performance.
What are your shipping speed and cost?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free to most locations, with expedited options available at checkout where applicable.
What is the warranty and return policy?
This product is covered by a 1-year warranty against manufacturing defects under normal marine use. If you encounter an issue, please contact our support team with your order details. Returns are accepted within our standard window for unused items in their original condition. See our policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part before purchase. If anything differs—even if your model appears compatible—do not install.
- This is an aftermarket replacement component, not an OEM part.
- Professional installation is recommended for safety and to ensure optimal performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions, typically arriving in 5–15 days.
- Manufacturer-Direct Value — We offer fair pricing by eliminating middlemen, without compromising on materials or quality control.
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