Intake Manifold Gasket Set – Fits GM V8 5.0L/5.7L/6.2L Vortec Engines (Replaces 27-807473A1, 3857662)
Intake Manifold Gasket Set – Fits GM V8 5.0L/5.7L/6.2L Vortec Engines (Replaces 27-807473A1, 3857662) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Intake Manifold Gasket Set – Fits GM V8 5.0L/5.7L/6.2L Vortec Engin...
Product Details
This Intake Manifold Gasket Set is engineered for GM-based V8 Vortec marine engines, including 5.0L, 5.7L, and 6.2L models from 1996 to the present. It provides a reliable seal for engines used by Mercruiser, Volvo Penta, OMC, Yamaha, and Marine Power, designed specifically for the 8-bolt intake manifold configuration common to all Gen II Vortec engines.
It serves as a direct replacement for multiple OEM and aftermarket part numbers, including Mercruiser 27-807473A1, Volvo Penta 3857662, and Sierra 18-0488, ensuring a precise fit and restoring factory performance.
- Engineered for direct-fit installation on 8-bolt Vortec intake manifolds.
- Designed for gasoline-fueled marine environments.
- Installation requires the use of black silicone for the end rail seals to ensure a complete seal.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercruiser | 27-807473A1 |
| Mercruiser | 807473A1 |
| Volvo Penta | 3857662 |
| Volvo Penta | 3856394 |
| Sierra | 18-0488 |
| GM | 89017465 |
| GM | 12561347 |
| Indmar | S556099 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercruiser models, this gasket fits all GEN+ engines with an 8-bolt intake manifold, including carbureted, EFI, and MPI versions.
For Volvo Penta, this set is compatible with Gen II Vortec engines.
For OMC, this gasket is for Gen II Vortec V8 models from 1996 onward.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercruiser | 350 MAG (GEN+) Alpha/Bravo | 350 | 4-Stroke | 1996–Present | 27-807473A1 | All Gen+ with 8-bolt intake manifold |
| Mercruiser | 350 MAG MPI (GEN+) | 350 | 4-Stroke | 1996–Present | 27-807473A1 | Including Horizon versions |
| Mercruiser | 5.0L MPI Alpha/Bravo | 305 | 4-Stroke | 1998–Present | 27-807473A1 | All Gen+ models |
| Mercruiser | 5.7L MPI/EFI | 350 | 4-Stroke | 1996–Present | 27-807473A1 | Including carbureted versions |
| Mercruiser | 6.2L MPI | 377 | 4-Stroke | 1998–Present | 27-807473A1 | Including MX 6.2L models |
| Mercruiser | Scorpion 350/377 | 350-377 | 4-Stroke | 1997–2014 | 27-807473A1 | All variants including EC models |
| Mercruiser | Black Scorpion 350/MX | 350-377 | 4-Stroke | 1996–2002 | 27-807473A1 | All SKI Gen+ models |
| Volvo Penta | 5.0 OSi | 270 | 4-Stroke | 1996–Present | 3857662 | Vortec (Gen II) engines |
| Volvo Penta | 5.7 OSi/OSi-E | 280 | 4-Stroke | 1996–2006 | 3857662 | Vortec (Gen II) engines |
| Volvo Penta | 5.7Gi | 280 | 4-Stroke | 1996–Present | 3857662 | Vortec (Gen II) engines |
| OMC | 5.0L/5.7L V8 | 305-350 | 4-Stroke | 1996–Present | 3856394/3857662 | Gen II Vortec engines |
Technical Specs
- Product Type
- Intake Manifold Gasket Set
- Installation
- Direct replacement for OEM gaskets
- Fuel Type
- Gasoline
- Housing Material
- Paper/Composite with metal core
- Dimensions
- Height: 1.5 in, Width: 8.5 in, Length: 51.5 in
- Compatible Manifold
- Fits 8-bolt intake manifold used on Vortec engines
- Warranty
- 1 Year
What’s in the Box
- 1 x Intake Manifold Gasket Set (Includes both side gaskets)
Installation Notes
- Ensure the engine is cool. Disconnect the battery and drain the cooling system.
- Remove components obstructing the intake manifold, such as the throttle body, fuel lines, and electrical connectors. Label everything for reassembly.
- Unbolt and carefully remove the intake manifold from the cylinder heads.
- Thoroughly clean the gasket mating surfaces on both the cylinder heads and the intake manifold. Remove all old gasket material and residue.
- Position the new intake gaskets onto the cylinder heads. Ensure they align correctly with the ports.
- Apply a bead of black silicone (RTV) sealant to the front and rear end rail surfaces on the engine block.
- Reinstall the intake manifold, torquing the bolts to the manufacturer's specified sequence and values.
- Reconnect all previously removed components and refill the cooling system.
Troubleshooting & FAQ
How can I confirm this gasket fits my engine?
This gasket set is designed for GM V8 Vortec engines (5.0L, 5.7L, 6.2L) manufactured from 1996 to present. The key identifier is the 8-bolt intake manifold. If your engine is in this family and has an 8-bolt pattern, this gasket should fit. Always cross-reference with the OEM part numbers provided.
What are the signs of a failing intake manifold gasket?
Common symptoms include external coolant leaks (puddles under the vehicle), engine overheating, a sweet smell of antifreeze, rough idling, and poor engine performance. You may also find coolant mixed with your engine oil, resulting in a milky appearance on the dipstick.
Is sealant required for this gasket set?
Yes. While the side gaskets are designed to be installed dry, a bead of black RTV silicone sealant is required for the front and rear intake manifold end rail seals on the engine block.
What is the recommended replacement interval for these gaskets?
There is no fixed replacement interval, but intake manifold gaskets should be inspected during any major engine service. They typically last for many years but can fail due to age, heat cycles, and exposure to coolant and oil. Replace them whenever the intake manifold is removed or if you notice any signs of failure.
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.
Payment & Security
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