Lower Unit O-Ring Seal Kit – Fits Volvo Penta SX/DPS Series (Replaces 3852045, 3855081)

Lower Unit O-Ring Seal Kit – Fits Volvo Penta SX/DPS Series (Replaces 3852045, 3855081)

This lower unit o-ring seal kit is designed for Volvo Penta SX-M, SX-A, DPS-A, and DPS-B series inboard/outboard engines, covering various ratio models. It provides the essential seals for the oil drainage and ventilation system, ensuring a reliable, leak-free seal.

It serves as a direct replacement for Volvo Penta part numbers 3852045 (dipstick) and 3855081 (vent/drain), as well as aftermarket equivalents including Sierra 18-7116/18-7145, GLM 81100, and Johnson/Evinrude 303067/329381/332584.

• Direct Fit Installation: Engineered to match OEM specifications for a secure, hassle-free replacement.
• Essential Sealing: Includes three critical O-rings for the dipstick, vent, and drain screw plugs to prevent water intrusion and oil leaks.
• Durable Construction: Made from high-quality rubber designed to withstand the harsh marine environment and resist degradation from gear oil.

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 Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

For Johnson/Evinrude owners, here’s a guide to help you identify your engine’s serial/model: Johnson/Evinrude Serial Number Guide.

Volvo Penta Models

Mercury/OMC/Johnson/Evinrude Models

Technical Specifications

Package Contents

This kit includes three replacement o-ring seals:

• 1 x Dipstick O-Ring (Replaces OEM Part Number 3852045)
• 1 x Vent O-Ring (Replaces OEM Part Number 3855081)
• 1 x Drain O-Ring (Replaces OEM Part Number 3855081)

Explosion Diagram

Installation Guide

1. Ensure the engine is off and the sterndrive is trimmed up for safe access.
2. Place an oil pan or suitable container underneath the drain plug on the lower gear unit.
3. Locate and remove the drain/fill screw, vent screw, and dipstick.
4. Allow all the old gear lube to drain completely from the unit.
5. Carefully remove the old, worn o-rings from each of the three plugs using a small pick. Avoid scratching the plug or gearcase surfaces.
6. Thoroughly clean the plugs and their sealing surfaces on the gear case.
7. Lightly coat the new o-rings with fresh marine gear lube before installation.
8. Install the new o-rings onto the corresponding plugs, ensuring they are seated correctly in their grooves.
9. Reinstall the drain plug and begin filling the lower unit with manufacturer-recommended gear lube through the drain hole until lube flows out of the vent hole.
10. Install the vent plug, then remove the fill tube and quickly install the drain plug.
11. Tighten all plugs to the torque specified in your service manual. Clean any excess oil and check for leaks.

Troubleshooting & FAQ

Q: How do I know if this o-ring kit will fit my sterndrive?

A: This kit is specifically designed for Volvo Penta SX, and DPS series sterndrives. To confirm compatibility, check your engine or drive model against the "Compatible Engine Models" table and verify that your existing part numbers match 3852045 or 3855081. It also cross-references with parts from OMC, Johnson/Evinrude, and Mercury.

Q: What are the signs that my old o-rings have failed?

A: Common signs of failure include visible gear oil leaking from the drain, vent, or dipstick plugs, or finding that your gear lube is milky and contaminated with water during a routine check. Either indicates a compromised seal that needs immediate attention.

Q: How often should I replace my lower unit o-rings?

A: It is highly recommended to replace these o-rings every time you change your lower unit's gear lube. This is typically done at the end of each boating season or according to the service interval specified by your engine's manufacturer.

Q: Is it difficult to install these o-rings myself?

A: The installation is straightforward for those familiar with basic marine maintenance. It simply involves removing the plugs, swapping the old o-rings for the new ones, and reinstalling. However, if you are unsure, we recommend consulting a professional marine mechanic.

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.