Lower Unit Gearcase Seal Kit – Fits Volvo Penta & OMC Cobra SX 3.0-8.2L (Replaces 3855275)
Lower Unit Gearcase Seal Kit – Fits Volvo Penta & OMC Cobra SX 3.0-8.2L (Replaces 3855275) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Lower Unit Gearcase Seal Kit – Fits Volvo Penta & OMC Cobra SX ...
Product Details
This comprehensive Lower Unit Gearcase Seal Kit provides all necessary components to service the lower unit on Volvo Penta SX sterndrives (1994–2006) and OMC Cobra SX sterndrives (1994–1998). It is designed for sterndrives paired with engines ranging from 3.0L to 8.2L, ensuring a precise fit for a wide range of models.
This kit serves as a direct replacement for Volvo Penta 3855275, OMC 3855275, Sierra 18-2598, GLM 87750, and EMP 26-08532, offering a reliable aftermarket alternative to OEM parts.
- Engineered and manufactured in the USA by JLM Marine.
- Includes all necessary seals and O-rings for a complete lower unit service.
- Professional installation is recommended to ensure proper fit and function.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Volvo Penta | 3855275 |
| OMC | 3855275 |
| Sierra | 18-2598 |
| GLM | 87750 |
| EMP | 26-08532 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit is for Volvo Penta SX single propeller outdrives manufactured between 1994 and 2006.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Volvo Penta | SX Sterndrive | All HP Ratings | 4-Stroke | 1994–2006 | 3855275 |
This kit fits OMC Cobra SX single propeller outdrives manufactured between 1994 and 1998, covering a wide range of engine sizes.
| Brand | Model | Engine | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| OMC | Cobra SX | 3.0L (181 CID) 4-cyl | 4-Stroke | 1994–1998 | 3855275 |
| OMC | Cobra SX | 4.3L (262 CID) V6 | 4-Stroke | 1994–1998 | 3855275 |
| OMC | Cobra SX | 5.0L (305 CID) V8 | 4-Stroke | 1994–1998 | 3855275 |
| OMC | Cobra SX | 5.7L (350 CID) V8 | 4-Stroke | 1994–1998 | 3855275 |
| OMC | Cobra SX | 5.8L (351 CID) V8 | 4-Stroke | 1994–1998 | 3855275 |
| OMC | Cobra SX | 7.4L (454 CID) V8 | 4-Stroke | 1994–1998 | 3855275 |
| OMC | Cobra SX | 8.2L (502 CID) V8 | 4-Stroke | 1994–1998 | 3855275 |
Technical Specs
- Product Type
- Lower Unit (Gearcase) Seal Kit
- Installation
- Professional installation recommended
- Warranty
- 1 Year (Aftermarket kit)
- Other Technical Attributes
- Made in USA (JLM Marine)
What’s in the Box
- 1 x Lower Gear Case Seal Kit (Replaces 3855275)
- 1 x O-Ring (Replaces 18-7145-9)
- 1 x O-Ring (Replaces 18-7160-9)
- 1 x Water Supply Tube Seal (Replaces 18-32882/3852315)
- 1 x Water Seal Tube (Replaces 3854595)
- 2 x O-Rings (Replaces 3852866/3852959)
Installation Notes
- Position the sterndrive in the full down/trailered position and place a drain pan beneath the lower unit.
- Remove the lower and upper gearcase drain/fill screws to drain the gear lube completely.
- Remove the six nuts securing the lower unit to the upper housing and carefully separate the assembly.
- Disassemble the gearcase as needed to access the propeller shaft seals, driveshaft seals, and shift shaft seals.
- Carefully remove all old seals and O-rings, taking note of their orientation. Thoroughly clean the seal seating surfaces.
- Lubricate the new seals with a light coat of 2-4-C marine grease or gear lube before installation.
- Use appropriate seal drivers to press the new seals into place until they are fully and squarely seated.
- Reassemble the gearcase components and reinstall the lower unit, ensuring the shift linkage and water tube are properly aligned.
- Refill the gearcase with fresh, high-quality marine gear lubricant according to manufacturer specifications.
Troubleshooting & FAQ
How do I confirm this kit fits my specific sterndrive?
This kit is specifically for Volvo Penta SX and OMC Cobra SX single-propeller sterndrives within the specified year ranges (1994–2006 for Volvo, 1994–1998 for OMC). Please verify your drive model and year before ordering. It does not fit DuoProp or King Cobra models.
What are the signs of a failing gearcase seal?
Common symptoms include milky, white, or grey gear lube (indicating water intrusion), visible oil leaking from the propeller shaft or drain screws, or metal shavings on the magnetic drain plug, which can result from corrosion caused by water.
Are special tools required for this installation?
Yes, professional installation is recommended. Specialized tools such as a seal puller, seal drivers, a bearing carrier retainer wrench, and a pressure/vacuum tester are often required to properly replace lower unit seals without damaging them or the gearcase housing.
How often should lower unit seals be replaced?
As a preventative measure, many marine mechanics recommend replacing the water pump impeller and all lower unit seals every 3-5 years or 300-500 operating hours, depending on use (freshwater vs. saltwater). They should be replaced immediately if any signs of leaking are detected.
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 a& 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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