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, DPS, and related sterndrive series, providing essential seals for the dipstick, vent, and drain plugs. The kit contains three o-rings that prevent gear oil leakage and water intrusion in the lower unit.

This kit directly replaces parts for a wide range of brands, including Volvo Penta, Sierra, GLM, Johnson/Evinrude, Mercury, and OMC.

• Installation: Direct fit replacement for drain, vent, and dipstick plugs.
• Material: High-grade rubber designed to resist gear oil and marine environments.
• Compatibility: Fits various sterndrive models from Volvo Penta, Mercury, Johnson/Evinrude, and OMC.

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

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.

Volvo Penta Models

Mercury/OMC/Johnson/Evinrude Models

Technical Specifications

Package Contents

• 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)

Installation Guide

1. Position a drain pan under the lower unit of your sterndrive.
2. Carefully remove the upper vent screw and the lower drain/fill screw. Allow all the old gear oil to drain completely.
3. Inspect and remove the old o-ring seals from the dipstick, vent, and drain plugs.
4. Clean the plug threads and the sealing surfaces on the lower unit to ensure they are free of old sealant, dirt, and debris.
5. Install the new o-rings onto the corresponding plugs, ensuring they are seated correctly.
6. Begin filling the lower unit with the manufacturer-recommended gear oil through the bottom drain hole.
7. Continue filling until oil begins to seep out of the upper vent hole, which indicates the drive is full.
8. Reinstall the top vent screw first, then quickly remove the fill nozzle and reinstall the bottom drain screw.
9. Tighten both screws to the manufacturer’s specified torque with a new gasket. Do not overtighten, as this can damage the seals or casing.
10. Clean off any excess oil and monitor the plugs for any signs of leakage.

Troubleshooting & FAQ

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

A: This kit is designed for Volvo Penta SX, DPS, and related series, as well as select models from Mercury, Johnson/Evinrude, and OMC. Please review the "Part Number Cross-Reference" and "Compatible Engine Models" tables on this page to confirm a match with your engine's part number and model.

Q: What are the signs that my lower unit o-rings need replacing?

A: The most common signs of failing seals are gear oil leaking from the drain or vent plugs, or a milky, gray appearance in your gear oil, which indicates water intrusion. We recommend inspecting the seals during every gear oil change.

Q: How often should I replace these seals?

A: It is best practice to replace the drain, vent, and dipstick o-rings every time you change your lower unit's gear oil, which is typically done annually or according to your engine manufacturer's service schedule.

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.