Outdrive Mounting Gasket Set – Fits OMC Cobra & Volvo Penta SX Drives (Replaces 508105, 915840)

Outdrive Mounting Gasket Set – Fits OMC Cobra & Volvo Penta SX Drives

This high-quality aftermarket mounting gasket set is designed for OMC Cobra Sterndrives (1986–1993) and various Volvo Penta SX-series drives, including SX-S, SX-C, SX-R, SX-M, and DP-S models. It provides a reliable seal where the sterndrive assembly attaches to the transom.

This kit serves as a direct replacement for OMC part numbers 508105, 915840, 0915840, 0508105, and 0911836, and Volvo Penta numbers 3852560, 3852565, 911823, and 911851.

• Installation Type: Direct replacement for a seamless fit.
• Complete Kit: Includes the main mounting gasket, seal, and O-rings required for the job.
• Durable Construction: Made from OEM-specification materials to ensure a long-lasting seal against water intrusion.

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.

OMC Applications

Volvo Penta Applications

Technical Specifications

Package Contents

• 1 x Outdrive Mounting Gasket (Replaces OMC 508105/915840)
• 1 x Outdrive Seal
• 2 x O-rings

Installation Guide

1. Safety First: Ensure the engine is off and disconnect the battery before starting work.
2. Position Drive: Trim the sterndrive to a position that allows for safe and easy access to the mounting bolts.
3. Separate Drive: Carefully unbolt and separate the sterndrive from the gimbal housing/transom assembly.
4. Clean Surfaces: Remove the old gasket, seal, and any debris or old sealant from the mating surfaces. Ensure both surfaces are clean and dry.
5. Install New Gasket: Place the new gasket, seal, and O-rings in their correct locations on the transom assembly.
6. Reattach Drive: Carefully align and reattach the sterndrive to the transom assembly.
7. Torque Bolts: Tighten the mounting bolts to the manufacturer's specified torque sequence and values.
8. Final Checks: Reconnect the battery. After launching, run the engine and check thoroughly for any water leaks around the transom assembly.

Troubleshooting & FAQ

How do I confirm this gasket set fits my sterndrive?
Verify your sterndrive model and year falls within the compatibility list (OMC Cobra 1986–1993 or Volvo Penta SX Series). The most reliable method is to cross-reference your old part number with the numbers listed in our cross-reference table.

Where is this gasket installed?
This gasket set is used to create the main seal where the outdrive unit attaches to the boat's transom shield or gimbal housing.

What are the signs that my mounting gasket is failing?
The most common sign of a failed mounting gasket is water leaking into the bilge area from around the transom assembly. You may also notice corrosion or physical degradation of the gasket material during inspection.

OEM vs. Aftermarket?
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.

How fast do you ship and how much does it cost?
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.

What is your warranty and return policy?
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.