Intake Manifold Gasket – Fits MerCruiser/GM 454, 482, 502 Big Block Engines (Replaces 17341)
Intake Manifold Gasket – Fits MerCruiser/GM 454, 482, 502 Big Block Engines (Replaces 17341) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Intake Manifold Gasket – Fits MerCruiser/GM 454, 482, 502 Big Block...
Product Details
This high-quality Intake Manifold Gasket is designed for MerCruiser/GM 454 cubic inch (7.4L), 482, and 502 cubic inch (8.2L) Gen V big block engines. It is specifically compatible with models featuring rectangular (square) intake ports, primarily carbureted engines manufactured between approximately 1978 and 1997.
This part directly replaces MerCruiser part numbers 27-818188, 8181881, and 27-805403A1, as well as aftermarket equivalents from Fel-Pro (17341) and Sierra (18-2930).
- Installs between the intake manifold and cylinder heads to create a reliable seal.
- Printoseal construction with a rubber-fiber base is resistant to coolant, gasoline, alcohol, and oil.
- The package includes two gaskets, providing a complete set for one engine.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| MerCruiser | 27-818188 |
| MerCruiser | 8181881 |
| MerCruiser | 27-805403A1 |
| Fel-Pro | 17341 |
| Sierra | 18-2930 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|
| MerCruiser | 454 Magnum | 4-Stroke | 1978–1997 | 27-818188, 8181881 | Gen V with rectangular ports |
| MerCruiser | 454 King Cobra | 4-Stroke | 1978–1997 | 27-818188, 8181881 | Gen V with rectangular ports |
| MerCruiser | 482 | 4-Stroke | 1978–1997 | 27-818188, 8181881 | Gen V with rectangular ports |
| MerCruiser | 502 Magnum | 4-Stroke | 1978–1997 | 27-818188, 8181881 | Gen V with rectangular ports |
| MerCruiser | 502 King Cobra | 4-Stroke | 1978–1997 | 27-818188, 8181881 | Gen V with rectangular ports |
| MerCruiser | 7.4L EFI | 4-Stroke | 27-805403A1 | Gen V & VI with EFI, 8-bolt intake |
Technical Specs
- Product Type
- Intake Manifold Gasket
- Installation
- Between intake manifold and cylinder heads
- Fuel Type
- Primarily for carbureted engines; not recommended for EFI applications per Fel-Pro.
- Housing Material
- Printoseal construction with rubber-fiber base
- Dimensions
- Height: 4.0 cm, Width: 14.0 cm, Length: 64.0 cm
- Weight
- 0.28 kg (0.62 lb)
- Port Style
- Rectangular/Square
- Other Attributes
- Resistant to coolant, gasoline, alcohol, and oil
What’s in the Box
- 2 x Intake Manifold Gasket (17341)
Installation Notes
- Disconnect the battery and completely drain the engine cooling system.
- Remove the air cleaner assembly, carburetor or throttle body, and distributor cap.
- Carefully disconnect all fuel lines, vacuum hoses, and electrical connectors attached to the intake manifold.
- Loosen and remove the intake manifold mounting bolts in the reverse order of the manufacturer's specified tightening sequence.
- Lift the intake manifold off the engine block. Be prepared for some residual coolant to spill.
- Thoroughly clean the gasket mating surfaces on both the cylinder heads and the intake manifold, ensuring all old gasket material and sealant is removed.
- Apply RTV sealant to the front and rear block rails ("china walls") and a thin bead around the coolant ports on the gaskets as specified by the engine service manual.
- Carefully place the new gaskets onto the cylinder heads, confirming they are correctly aligned with the ports and bolt holes.
- Lower the intake manifold into place and hand-start all mounting bolts to ensure proper alignment.
- Torque the manifold bolts in the correct sequence and to the specific torque values required by the manufacturer. This is often done in multiple stages.
- Reassemble all components (distributor, fuel lines, hoses, etc.) that were previously removed.
- Refill the cooling system, check all fluid levels, and inspect for any leaks before starting the engine.
Troubleshooting & FAQ
Will this gasket fit my EFI engine?
This gasket is primarily designed for carbureted Gen V big block engines. While it is cross-referenced to a part used on some EFI models, we strongly recommend using a gasket specifically designated for your fuel-injected application, as port sizes and sealing requirements may differ.
What are the signs of a failing intake manifold gasket?
Common symptoms include engine overheating, unexplained coolant loss, coolant leaking externally from the top of the engine, milky-white engine oil (indicating coolant contamination), rough idling, vacuum leaks, and decreased engine performance or misfires.
Do I need to use sealant with these gaskets?
Yes. While the gaskets feature a Printoseal sealing bead, you must also apply RTV gasket maker to the front and rear "china walls" of the engine block. It is also best practice to apply a thin film of sealant around the coolant ports on the gasket itself for added security. Always follow the instructions in your engine's service manual.
Is this a complete set for one engine?
Yes, this item includes two gaskets, which is the complete set required for one V-style engine (one for each cylinder head).
What is the main cause of intake gasket failure?
The primary cause of failure is repeated heat cycles over time, which can make the original gasket material brittle and prone to cracking. Degradation from exposure to engine oil and coolant, as well as improper installation or torque procedures, can also lead to premature 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.
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