Lower Unit Gearcase Seal Kit – Fits Volvo Penta SX & OMC Cobra SX 3.0-8.2L V6/V8 (Replaces 3855275)

Lower Unit Gearcase Seal Kit – Fits Volvo Penta SX & OMC Cobra SX 3.0-8.2L V6/V8 (Replaces 3855275)

This lower unit gearcase seal kit provides the necessary components to service sterndrives on specific Volvo Penta and OMC models. It is designed to fit Volvo Penta SX sterndrives from 1994–2006 and OMC Cobra SX sterndrives from 1994–1998, covering V4, V6, and V8 engines ranging from 3.0L to 8.2L.

This assembly is a direct replacement for OEM part numbers Volvo Penta 3855275, OMC 3855275, Sierra 18-2598, GLM 87750, and EMP 26-08532, ensuring compatibility and fitment.

• Includes a comprehensive set of seals and O-rings for a complete lower gearcase service.
• Engineered to meet or exceed OEM specifications for reliable, leak-free performance.
• Professional installation is recommended to ensure proper seating and function.

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.

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 lubricant completely from the lower unit.
2. Carefully remove the propeller assembly and then unbolt and detach the lower unit from the sterndrive.
3. Disassemble the gearcase to access the propeller shaft and driveshaft bearing carriers. Note the position and orientation of old seals.
4. Using appropriate tools, carefully extract all old seals and O-rings, taking care not to scratch or damage the housing surfaces.
5. Thoroughly clean all sealing surfaces and component bores of any old adhesive or sealant residue.
6. Lightly coat the new seals and O-rings with marine grease before installation.
7. Use a suitable seal driver or socket to press the new seals evenly into place until they are fully seated.
8. Reassemble all components in the reverse order of disassembly, ensuring correct alignment.
9. Install the new water supply tube seal and related O-rings carefully.
10. Reattach the lower unit to the sterndrive, torquing bolts to the manufacturer's specification.
11. Refill the gearcase with the correct type and amount of new marine gear lubricant.
12. Before operating the boat, inspect for any signs of oil or water leaks around the newly sealed areas.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my sterndrive?

A: This kit is specifically designed for Volvo Penta SX (1994–2006) and OMC Cobra SX (1994–1998) sterndrives. The most reliable method is to cross-reference your existing part number with the OEM number 3855275. Please consult the detailed compatibility tables on this page to verify your specific model and year.

Q: What are the signs my gearcase seals are failing?

A: Common symptoms include finding water in your gear lube (it will appear milky or creamy), visible oil leaks from the propeller shaft area, or a persistent need to top off the gear lube. Replacing seals is critical to prevent catastrophic gear damage.

Q: Is this kit all I need for the replacement?

A: This kit contains all the required seals and O-rings for the job as listed in the "Package Contents." You will also need your own tools, marine-grade grease for lubrication, and fresh gear lubricant for the refill.

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.