Lower Gear Case Seal Kit for Volvo Penta SX & OMC Cobra SX Sterndrives – Replaces 3855275
Lower Gear Case Seal Kit for Volvo Penta SX & OMC Cobra SX Sterndrives – Replaces 3855275 is backordered and will ship as soon as it is back in stock.
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Lower Gear Case Seal Kit for Volvo Penta SX & OMC Cobra SX Ster...
Lower Gear Case Seal Kit for Volvo Penta SX & OMC Cobra SX Sterndrives – Replaces 3855275 is backordered and will ship as soon as it is back in stock.
Product Details
This lower gear case seal kit is intended for resealing compatible Volvo Penta SX and OMC Cobra SX sterndrive gear housings. It is a replacement seal kit for the lower unit and is suitable for service work where the original gearcase seals require replacement.
Catalog references identify this application as a replacement for Volvo Penta OEM part number 3855275. The corresponding aftermarket references include Sierra 18-2598 and GLM 87750.
- Lower unit and gear housing seal kit.
- For compatible single-propeller Volvo Penta SX and OMC Cobra SX sterndrives.
- Designed to replace worn or leaking lower gearcase sealing components.
- Verify the sterndrive model and original part number before ordering.
Part Number Matrix
The following references are listed for identification and cross-reference purposes. They do not replace verification against the exact sterndrive configuration.
| Brand | Part Number | Reference |
|---|---|---|
| Volvo Penta | 3855275 | OEM replacement reference |
| Sierra | 18-2598 | Lower unit seal kit reference |
| GLM | 87750 | Gear housing seal kit reference |
Compatibility
Available catalog references associate this seal kit with the following sterndrive families. Confirm the model designation and original part number before installation.
| Brand | Sterndrive Model | Applicable Years | OEM Reference | Notes |
|---|---|---|---|---|
| Volvo Penta | SX | Through 2006 | 3855275 | Lower unit seal kit application |
| OMC | Cobra SX | 1994 and newer | 3855275 | Gear housing seal kit application |
This listing is for the compatible lower gearcase seal kit application above. It is not confirmed for Volvo Penta SX-A, DPS, Duoprop, Bravo, or other sterndrive families unless the original part number and service documentation confirm compatibility.
Technical Specs
- Product Type
- Lower gear case seal kit
- Application
- Compatible Volvo Penta SX and OMC Cobra SX sterndrives
- Installation
- Replacement service part
- Primary OEM Reference
- 3855275
- Aftermarket References
- Sierra 18-2598; GLM 87750
- Package Contents
- Seal kit components for the lower gearcase; exact component count and individual item list should be confirmed from the package labeling before installation.
What’s in the Box
The package contains the seal components supplied for the compatible lower gearcase application. Because the available catalog records identify the product as a seal kit but do not publish a verified piece-by-piece contents list, do not rely on an assumed quantity or component list. Compare the supplied parts with the service manual and the seals removed from your sterndrive before beginning assembly.
Installation Notes
- Confirm the sterndrive model, year range, and original part number before starting work.
- Turn off the engine, disconnect the battery, and support the sterndrive safely according to the manufacturer's service procedure.
- Drain the gearcase lubricant into an approved container and remove the sterndrive or lower unit as required by the service manual.
- Disassemble the lower gearcase only as directed by the service manual for the specific drive.
- Remove the old seals carefully and inspect the shafts, bores, housings, and sealing surfaces for wear or corrosion.
- Clean all sealing surfaces and compare each replacement component with the removed part before installation.
- Lubricate and install the new seals using the correct orientation and suitably sized seal drivers. Do not hammer directly on sealing lips or precision surfaces.
- Reassemble the gearcase and torque fasteners to the manufacturer's specified values and sequence.
- Refill the gearcase with the lubricant specified for the sterndrive.
- Perform the manufacturer's recommended pressure and vacuum tests before returning the sterndrive to service.
Troubleshooting & FAQ
How do I know if my gearcase seals are failing?
Milky or cloudy gear lubricant can indicate water intrusion. Other signs may include lubricant leakage around the propeller-shaft area or a failed pressure test. Inspect the drive and follow the manufacturer's diagnostic procedure before replacing seals.
Will this kit fit a dual-propeller drive such as a Volvo Penta Duoprop?
Do not assume compatibility with Duoprop, SX-A, DPS, Bravo, or another drive family. This listing is associated with Volvo Penta SX and OMC Cobra SX lower gearcase applications using the referenced part number. Verify the original part number and service documentation before ordering.
Does this kit fit every engine installed with an SX drive?
Compatibility is determined by the sterndrive and gearcase configuration rather than engine displacement alone. Confirm the exact drive model, year, and original seal-kit reference.
Do I need special tools for installation?
Professional installation is recommended. The job may require a seal puller, correctly sized seal drivers, a torque wrench, and pressure/vacuum testing equipment. Follow the official service manual for the required tools and procedures.
Is this an OEM part?
This is an aftermarket replacement seal kit. The listed OEM and aftermarket numbers are provided for identification and cross-reference only.
How should I verify fitment?
Compare the sterndrive model, production year, original part number, and the supplied component shapes with the service manual before installation. If any identifying detail differs, contact support before ordering.
Shipping speed and cost
Shipping options and delivery estimates are shown at checkout where available.
Warranty and returns
Warranty and return eligibility are subject to the terms shown for your order and the applicable store policy. Contact support with your order details if assistance is needed.
Safety & Important Information
- Verify the sterndrive model, year, original part number, and supplied components before installation.
- Use the manufacturer's service manual for disassembly, seal orientation, torque values, lubricant type, and pressure testing.
- Do not operate the sterndrive if lubricant leakage or a failed pressure test remains after installation.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safe and reliable service.
About Sea Sierra
- Marine Replacement Parts — We supply aftermarket components for common marine service applications.
- Fitment-Focused Support — Use the model and part-number information on this page to verify your application before ordering.
- Service-Ready Information — Always follow the applicable manufacturer's service documentation during installation.
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