End Cap Gasket – Fits Mercury Mercruiser 3.0L GM 181 I/L4 Engines (Replaces 27-480431)
End Cap Gasket – Fits Mercury Mercruiser 3.0L GM 181 I/L4 Engines (Replaces 27-480431) 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
End Cap Gasket – Fits Mercury Mercruiser 3.0L GM 181 I/L4 Engines (...
Product Details
This is a direct replacement End Cap Gasket designed for Mercury Mercruiser 3.0L and 3.0LX GM 181 I/L4 4-stroke engines from 1972 to current models. It ensures a proper seal between the end cap and the exhaust manifold, preventing exhaust leaks and maintaining engine performance.
It serves as a direct interchange for Mercury 27-480431, Sierra 18-2832-1, and Quicksilver 27-480431.
- Made from high-quality OEM composite material for durability and proper sealing.
- Installs as a flat gasket and requires following the correct torque sequence for the bolts.
- Engineered for the specific application of sealing the end cap to the exhaust manifold.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 27-480431 |
| Sierra | 18-2832-1 |
| Quicksilver | 27-480431 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 140 GM 181 I/L4 | 140 | 4-Stroke | 1972–1978 | 27-480431 | Serial 3332138-5157668 |
| Mercury | 3.0L GM 181 I/L4 | 135 | 4-Stroke | 1990–1994 | 27-480431 | Serial 0C856559-0F353099 |
| Mercury | 3.0L GM 181 I/L4 | 135 | 4-Stroke | 1998 | 27-480431 | Serial 0L010042-0L096999 |
| Mercury | 3.0L GM 181 I/L4 | 135 | 4-Stroke | 1998–2001 | 27-480431 | Serial 0L097000-0W301999 |
| Mercury | 3.0L GM 181 I/L4 | 135 | 4-Stroke | 2001–2002 | 27-480431 | Serial 1A002000-1A020543 |
| Mercury | 3.0L GM 181 I/L4 | 135 | 4-Stroke | 2002–Current | 27-480431 | Serial 1A020544 & Up |
| Mercury | 3.0LX GM 181 I/L4 | 135 | 4-Stroke | 1990–1995 | 27-480431 | Serial 0C856559-0F603999 |
| Mercury | 3.0LX GM 181 I/L4 | 135 | 4-Stroke | 1996–1997 | 27-480431 | Serial 0F604000-0K999999 |
| Mercury | 3.0L TKS Plus | 135 | 4-Stroke | 2008–Current | 27-480431 | Serial 1G404114 & Up |
Technical Specs
- Product Type
- End Cap Gasket
- Application
- End cap to exhaust manifold
- Material
- OEM composite material
- Dimensions
- 6.0" x 7.5" x 1.06"
- Housing Color
- Black/gray
What’s in the Box
- 1 x Gasket (27-480431)
Installation Notes
- Disconnect the boat's battery and ensure the engine is completely cool.
- Access the exhaust manifold and remove any components obscuring the end cap.
- Carefully unbolt and remove the end cap.
- Remove the old gasket. Thoroughly clean all residue from both the manifold and end cap mating surfaces.
- Position the new gasket correctly onto the manifold.
- Reinstall the end cap. Tighten the bolts in the sequence and to the torque specified in your engine's service manual to ensure an even seal.
- Reconnect the battery. After starting the engine, check for any signs of exhaust leaks around the end cap.
Troubleshooting & FAQ
How do I know if this gasket fits my engine?
This gasket is for specific Mercury Mercruiser 3.0L GM 181 I/L4 engine models. Please verify your engine's model, year, and serial number against the compatibility table provided on this page. Matching the OEM part number (27-480431) is the best way to confirm fitment.
What are the signs of a failed end cap gasket?
Common signs include a noticeable exhaust leak (hissing or ticking sound from the engine), visible soot or black streaks around the end cap, water leaks in the engine bay, and a potential loss of engine performance or rough idle.
Do I need to use sealant with this gasket?
Generally, this type of composite gasket is designed to be installed dry. However, always refer to your specific engine's service manual for the manufacturer's recommendation, as some applications may call for a light application of a specific sealant.
What is the difference between this and an OEM part?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. All parts are manufactured in an ISO 9002 facility and are batch-inspected for quality and consistency.
What is your shipping speed & cost?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
What is the warranty and return policy?
Our parts are covered by a 1-year warranty against manufacturing defects under normal use. If you encounter an issue, please contact our support team with your order details. Returns are accepted within our standard window for unused items in their 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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