Lower Unit Gearcase Seal Kit – Fits Volvo Penta SX & OMC Cobra SX 3.0-8.2L (Replaces 3855275)

Lower Unit Gearcase Seal Kit – Fits Volvo Penta SX & OMC Cobra SX 3.0-8.2L (Replaces 3855275)

This seal kit provides the necessary components to service the lower unit gearcase on Volvo Penta SX sterndrives (1994–2006) and OMC Cobra SX sterndrives (1994–1998). It is designed for engines ranging from 3.0L to 8.2L.

This kit is a direct replacement for Volvo Penta 3855275, OMC 3855275, Sierra 18-2598, GLM 87750, and EMP 26-08532.

• Includes all necessary seals and O-rings for a lower gearcase service.
• Made in the USA by JLM Marine to meet or exceed OEM specifications.
• Professional installation is recommended for this part.

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.

Volvo Penta Applications

OMC Applications

Technical Specifications

Package Contents

• 1 x Lower Gear Case Seal Kit (Replaces 3855275)
• 1 x O-Ring (Replaces 18-7145-9)
• 1 x O-Ring (Replaces 18-7160-9)
• 1 x Water Supply Tube Seal (Replaces 18-32882/3852315)
• 1 x Water Seal Tube (Replaces 3854595)
• 2 x O-Rings (Replaces 3852866/3852959)

Installation Guide

1. Drain the gearcase oil completely by removing the drain and vent screws.
2. Remove the lower unit assembly from the sterndrive housing.
3. Carefully disassemble the lower unit to access the propeller shaft, driveshaft, and shift shaft seals.
4. Remove all old seals, gaskets, and O-rings, taking care not to scratch the housing surfaces.
5. Thoroughly clean all sealing surfaces and component bores to remove any old sealant or corrosion.
6. Lightly grease the new seals and O-rings before installation to prevent damage.
7. Install the new seals into their respective bores using an appropriate seal driver, ensuring they are seated correctly.
8. Reassemble the lower unit components in the reverse order of disassembly.
9. Reinstall the lower unit onto the sterndrive, ensuring the water tube and shift shaft are properly aligned.
10. Refill the gearcase with fresh, high-quality marine gear lubricant according to the manufacturer's specification.
11. Install the vent and drain screws with new gaskets, and check for any leaks before operating.

Troubleshooting & FAQ

Q: How do I know if this seal kit fits my sterndrive?

A: This kit is specifically designed for Volvo Penta SX sterndrives made between 1994 and 2006, and OMC Cobra SX sterndrives made between 1994 and 1998. It serves as a direct replacement for OEM part number 3855275. To ensure a perfect match, please verify your sterndrive model and year against our compatibility chart and cross-reference your existing part number.

Q: What are the common signs that my lower unit seals are failing?

A: The most common indicator of a failed seal is milky, grey, or water-contaminated gear oil, which you can see when you drain the lubricant. Other signs include visible oil leaks around the propeller shaft or lower unit housing, or a persistent burning smell from the gearcase due to lubrication failure and friction.

Q: How often should the lower unit seals be replaced?

A: It is best practice to inspect your lower unit seals annually, typically during your end-of-season service when you change the gear oil. Seals should be replaced immediately if there are any signs of wear, cracking, damage, or leakage. Proactively replacing the seals every few years or whenever the lower unit is disassembled for other service can prevent catastrophic gear failure.

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.