Exhaust Manifold Gasket – Fits MerCruiser 120/140 HP 2.5L/3.0L 4-Cylinder (Replaces 27-96429, 18-1204)
Exhaust Manifold Gasket – Fits MerCruiser 120/140 HP 2.5L/3.0L 4-Cylinder (Replaces 27-96429, 18-1204) is backordered and will ship as soon as it is back in stock.
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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
Exhaust Manifold Gasket – Fits MerCruiser 120/140 HP 2.5L/3.0L 4-Cy...
Product Details
This high-quality Exhaust Manifold Gasket – Fits MerCruiser 120/140 HP 2.5L/3.0L 4-Cylinder Engines (Replaces 27-96429, 18-1204) creates a tight seal between the exhaust manifold and the cylinder head. It is designed for MerCruiser, Volvo Penta, and OMC 120-140 HP, 2.5L/3.0L (153/181 CID) 4-cylinder marine engines manufactured between 1982 and 1995.
It serves as a direct replacement for MerCruiser 27-96429, Sierra 18-1204 and 18-1204-1, GLM 33570, Mallory 9-61419, and OMC 0912164.
- Made from a marine-grade gasket compound with metal reinforcement for durability.
- Engineered to withstand high exhaust temperatures and pressure, preventing leaks.
- Mounts directly between the exhaust manifold and the cylinder head.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| MerCruiser | 27-96429 |
| Sierra | 18-1204 |
| Sierra | 18-1204-1 |
| GLM | 33570 |
| Mallory | 9-61419 |
| OMC | 0912164 |
| Aqua Power | 413 |
Engine & Model Compatibility
Confirm your engine model and year in the tables below. Note that this gasket does not fit MerCruiser 3.0LX models, which use a different part.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | 120 | 120 HP | 4-Stroke | 1982–1995 | 27-96429 | GM 153 CID (2.5L) 4-cyl |
| MerCruiser | 140 | 140 HP | 4-Stroke | 1982–1995 | 27-96429 | GM 181 CID (3.0L) 4-cyl |
| MerCruiser | 3.0L | 130-135 HP | 4-Stroke | 1990–1995 | 27-96429 | GM 181 CID, not for 3.0LX |
| MerCruiser | 3.0LX | 135 HP | 4-Stroke | 1990+ | 27-815528 | Not compatible with this gasket |
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| OMC | 3.0L | 140 HP | 4-Stroke | 1973–1990 | 0912164 | GM 181 CID engines |
| Volvo Penta | 3.0L | 130–140 HP | 4-Stroke | 1982–1990 | GM 181 CID engines |
Technical Specs
- Product Type
- Exhaust Manifold Gasket
- Installation
- Mounts between exhaust manifold and cylinder head
- Material
- Marine grade gasket compound with metal reinforcement
- Color
- Gray/metallic
- Compatible Engines
- GM 153 CID (2.5L) / GM 181 CID (3.0L) 4-cylinder
- Applications
- MerCruiser Wet Joint Model 120/140 HP, 3.0L/3.0LX engines
- Operating Temperature
- High temperature rated for exhaust systems
- Other Attributes
- Designed to withstand exhaust heat and pressure while preventing leaks between cylinder head and exhaust manifold
What’s in the Box
- 1 x Exhaust Manifold Gasket (Replaces 27-96429/18-1204)
Installation Notes
- Ensure the engine is completely cool and disconnect the battery.
- Drain the engine cooling system.
- Remove any components obstructing access to the exhaust manifold.
- Carefully unbolt and detach the exhaust manifold from the cylinder head.
- Remove the old gasket. Thoroughly clean and inspect both mating surfaces, ensuring they are flat, dry, and free of debris.
- Position the new gasket, verifying correct alignment with all bolt holes and ports.
- Re-install the exhaust manifold, starting all bolts by hand.
- Tighten the manifold bolts to the manufacturer's recommended torque specification and sequence.
- Refill the cooling system and reconnect the battery.
- Start the engine and carefully check for any exhaust or coolant leaks around the manifold.
Troubleshooting & FAQ
How do I know if my exhaust manifold gasket is failing?
Signs of a bad gasket include visible water or coolant leaks from the joint between the manifold and cylinder head, milky or contaminated engine oil, a rough-running engine, or signs of water inside the cylinders (which can lead to hydrolock). An audible exhaust leak (ticking sound) when the engine is running is also a common symptom.
Is this gasket compatible with my MerCruiser 3.0LX model?
No. This gasket is specifically for earlier MerCruiser 3.0L models (approx. 1990-1995) and does not fit the 3.0LX, which requires a different gasket (OEM part number 27-815528). Always verify your engine's model and part number before ordering.
Should I use sealant or adhesive with this gasket?
This gasket is designed to be installed dry. Applying sealant can interfere with the seal and may cause premature failure. Always follow the instructions in your engine's official service manual for the correct installation procedure.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Our parts are manufactured in an ISO 9002 facility and are batch-inspected for quality and consistency.
How much is shipping and how fast is it?
We ship worldwide quickly—typical transit time is 5–15 days. Standard shipping is free to most regions. Expedited shipping options, where available, will be displayed at checkout.
What is the warranty and return policy?
This part is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter any issues, please contact our support team with your order details. Returns are accepted within our standard window for items that are unused and in their original condition. See our policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement part, 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, typically arriving in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or quality control.
Payment & Security
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