Mercury Gasket 27-139581 – Fits Mercury/Mariner 100-125 HP 4-Cylinder Outboards

$22.56

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Product Details

This is an aftermarket Mercury Gasket 27-139581, designed for use with the exhaust baffle plate and cover (components 44324C1 and 44325C1). It provides a reliable seal between the baffle plate and cylinder block on compatible Mercury and Mariner 100, 115, and 125 HP 4-cylinder 2-stroke outboard engines.

It serves as a direct replacement for Mercury part 27-139581 and Sierra aftermarket part 18-2621.

Installation is a direct OEM-style replacement.
Forms a crucial seal for the exhaust baffle plate against the cylinder block.
Note: A complete repair requires two of these gaskets per engine.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Mercury	27-139581
Sierra	18-2621

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury and Mariner models, verify that your engine is a 4-cylinder 2-stroke model with the specified horsepower.

Brand	Model	Rated HP	Stroke	OEM Part No.	Notes
Mercury	100 (4 CYL.)	100	2-Stroke	27-139581
Mercury	115 (4 CYL.)	115	2-Stroke	27-139581
Mercury	125 (4 CYL.)	125	2-Stroke	27-139581
Mercury	80 JET (4 CYL.)	80 Jet	2-Stroke	27-139581	Based on 115 HP powerhead
Mariner	100 (4 CYL.)	100	2-Stroke	27-139581
Mariner	115 (4 CYL.)	115	2-Stroke	27-139581
Mariner	125 (4 CYL.)	125	2-Stroke	27-139581

Technical Specs

Product Type: Exhaust Baffle Plate Gasket
Installation: OEM Style Replacement
Application: Baffle Plate to Cylinder Block
OEM Reference: Use with 44324C1 and 44325C1
Dimensions: 13.5" H x 23.88" W x 0.13" L
Weight: 0.31 lb (0.14 kg)
Packaging: Individual
Quantity per Pack: 1

What’s in the Box

1 x Gasket (Replaces OEM 27-139581) for use with Baffle Plate 44324C1 and Cover 44325C1. Note: Two gaskets are required for a complete engine service.

Installation Notes

Disconnect the battery and ensure the engine is cool before starting.
Access the engine's exhaust manifold area to locate the exhaust baffle plate and cover.
Carefully remove the mounting bolts securing the cover and plate.
Remove the old baffle plate and the two gaskets on either side of it.
Thoroughly clean the mating surfaces on the cylinder block and the exhaust cover, ensuring they are free of old gasket material and debris.
Place one new gasket against the cylinder block, followed by the baffle plate, and then the second new gasket.
Reinstall the exhaust cover and tighten the bolts to the manufacturer's specified torque sequence and values.
Reconnect the battery and test the engine for exhaust leaks once the repair is complete.

Troubleshooting & FAQ

How do I confirm this gasket fits my specific engine model?

Check the Engine & Model Compatibility table on this page. Verify your engine's brand (Mercury/Mariner), horsepower (100, 115, 125 HP), and cylinder count (4 CYL.) match the listed applications. This gasket is specifically for the 2-stroke models shown.

Why do I need two of these gaskets for the repair?

This gasket seals the exhaust baffle plate (44324C1) to both the cylinder block and the exhaust baffle cover (44325C1). One gasket is installed on each side of the baffle plate, requiring a total of two for a complete and proper seal.

What are symptoms of a failing exhaust baffle gasket?

Common signs include a noticeable exhaust leak from the side of the engine block, an unusually loud or hissing exhaust sound, reduced engine performance, or visible soot/exhaust residue around the baffle cover area.

Is this gasket a direct replacement for Mercury part 27-139581?

Yes. This is a direct aftermarket cross-reference for OEM part number 27-139581. It also interchanges with Sierra Marine part 18-2621.

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

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