Outdrive Mounting Gasket Kit – Fits Volvo Penta, OMC Cobra (Replaces 508105, 915840)

$15.00

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Outdrive Mounting Gasket Kit – Fits Volvo Penta, OMC Cobra (Replaces 508105, 915840) is backordered and will ship as soon as it is back in stock.

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Product Details

This Outdrive Mounting Gasket Kit – Fits Volvo Penta SX/DP Drives & OMC Cobra Sterndrives (Replaces 508105, 915840) provides a reliable, watertight seal where the sterndrive assembly attaches to the transom shield. It is designed for OMC Cobra Sterndrives manufactured between 1986 and 1993, as well as a range of Volvo Penta SX-series and DP drives.

This kit serves as a direct replacement for multiple OEM and aftermarket part numbers, including OMC 508105/915840, Volvo Penta 3852560, Sierra 18-2613, GLM 39630, and Mallory 9-62605, ensuring a precise fit and function.

Engineered for direct replacement installation.
Made from OEM-specification rubber and composite materials for durability.
Includes all necessary gaskets, seals, and O-rings for a complete installation.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
OMC	508105
OMC	915840
OMC	0508105
OMC	0915840
OMC	0911836
Volvo Penta	3852560
Volvo Penta	3852565
Volvo Penta	911823
Volvo Penta	911851
Sierra	18-2613
GLM	39630
Mallory	9-62605

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For OMC applications, this kit is compatible with Cobra Sterndrives on 4-cylinder, V6, and V8 engines from 1986–1993.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
OMC	Cobra Sterndrives	85-130	4-Stroke	1986–1993	508105	2.3-3.0L 4-cylinder engines
OMC	Cobra Sterndrives	160-165	4-Stroke	1986–1993	508105	4.3L V6 engines
OMC	Cobra Sterndrives	185-240	4-Stroke	1986–1993	508105	5.0-5.7L V8 engines

For Volvo Penta applications, this kit fits various SX and DP-S series drives commonly used at the transom assembly from approximately 1994–2008.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Volvo Penta	SX Drives	Various	4-Stroke	1994–2008	3852560	SX-S, SX-C, SX-R, SX-M variants
Volvo Penta	DP-S Drives	Various	4-Stroke	1994–2008	3852560	Used at transom assembly

Technical Specs

Product Type: Outdrive/Sterndrive Mounting Gasket Kit
Installation: Direct replacement
Housing Material: OEM-specification rubber/composite materials
Weight: Approximately 0.06 kg (0.14 lbs)
Other Technical Attributes: Includes mounting gasket, seal, and O-rings

What’s in the Box

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

Installation Notes

Disconnect the battery and ensure the engine is off and cool.
Position the outdrive in the full tilt-up position and secure it safely.
Remove the trim-tilt rams and shift cable from the drive.
Unfasten the six mounting nuts and carefully remove the sterndrive assembly from the transom shield.
Remove the old gasket, seals, and O-rings. Thoroughly clean all mating surfaces, removing any old sealant or corrosion.
Apply a thin layer of appropriate marine-grade sealant to the new gasket.
Install the new gasket, seal, and O-rings in their correct positions.
Carefully guide the sterndrive back onto the transom shield, ensuring the drive shaft aligns with the engine coupler.
Tighten the six mounting nuts to the manufacturer's specified torque.
Re-attach the trim-tilt rams and shift cable.
Lower the drive, check fluid levels, and test for proper operation and leaks.

Troubleshooting & FAQ

How can I confirm this gasket kit fits my specific model?

The best way is to cross-reference your existing part number with those in the Part Number Matrix. If you cannot find a part number, compare our product photos and the models listed in the Engine & Model Compatibility tables with your application.

What are the signs of a failed outdrive mounting gasket?

Common signs include water leaking into the bilge from the transom area, visible corrosion around the sterndrive mounting flange, or a loose-feeling drive assembly. You may also notice performance issues related to water ingress.

Is any special sealant required for installation?

Yes, it is highly recommended to use a high-quality marine-grade sealant (such as Permatex Aviation Form-A-Gasket or equivalent) on the gasket surfaces to ensure a durable, waterproof seal.

How often should this gasket be replaced?

There is no fixed replacement interval. This gasket should be replaced any time the sterndrive is removed from the transom for service or if signs of a leak are detected.

Can I install this gasket myself?

While DIY installation is possible for experienced marine mechanics, we recommend professional installation. Incorrect installation can lead to catastrophic water leaks and damage to your vessel.

Is this kit for saltwater and freshwater use?

Yes, the materials are designed to resist corrosion and degradation in both saltwater and freshwater environments.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

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