Reed Block Gasket – Fits Mercury/Mariner 18-25 HP Outboards (Replaces 27-414172)

$5.78 $9.00

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Product Details

This Reed Block Gasket provides a precision seal between the reed block and intake assembly on Mercury/Mariner 18-25 HP 2-Stroke outboard engines manufactured between 1977 and 1988. It is engineered to prevent air leaks and ensure optimal engine performance.

This part is a direct replacement for Mercury part numbers 27-414172, 414172, 414171, and 41417, as well as GLM 36750.

Installs between the reed block and intake assembly.
Made from high-quality composite gasket material to ensure a durable seal.
Includes one gasket for a complete replacement.

Part Number Matrix

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

Brand	Part Number	Notes
Mercury	27-414172	Current OEM Part Number
Mercury	414172	Alternate OEM Number
Mercury	414171	Superseded by 27-414172
Mercury	41417	Superseded by 27-414172
GLM	36750	Aftermarket Interchange

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury models, this gasket fits a range of 18 HP, 20 HP, and 25 HP outboards from 1980 to 1988.

For Mariner models, compatibility includes 20 HP and 25 HP engines from as early as 1977 up to 1987.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.
Mercury	18 E	18	2-Stroke	1980–1984	27-414172
Mercury	18 EL	18	2-Stroke	1980–1984	27-414172
Mercury	18 M	18	2-Stroke	1980–1985	27-414172
Mercury	18 ML	18	2-Stroke	1980–1985	27-414172
Mercury	20 E	20	2-Stroke	1987	27-414172
Mercury	20 EL	20	2-Stroke	1987	27-414172
Mercury	20 M	20	2-Stroke	1986–1987	27-414172
Mercury	20 ML	20	2-Stroke	1986–1987	27-414172
Mercury	20 ML/ALT	20	2-Stroke	1986	27-414172
Mercury	25 E	25	2-Stroke	1980–1987	27-414172
Mercury	25 EH	25	2-Stroke	1985–1987	27-414172
Mercury	25 EL	25	2-Stroke	1980–1987	27-414172
Mercury	25 ELH	25	2-Stroke	1985–1987	27-414172
Mercury	25 M	25	2-Stroke	1980–1987	27-414172
Mercury	25 ML	25	2-Stroke	1980–1987	27-414172
Mercury	25XS Race	25	2-Stroke	1988	27-414172
Mariner	20 E	20	2-Stroke	1984–1987	27-414172
Mariner	20 EL	20	2-Stroke	1984–1987	27-414172
Mariner	20 M	20	2-Stroke	1977–1986	27-414172
Mariner	20 ML	20	2-Stroke	1984–1987	27-414172
Mariner	25 E	25	2-Stroke	1985	27-414172
Mariner	25 EH	25	2-Stroke	1987	27-414172
Mariner	25 EL	25	2-Stroke	1985–1987	27-414172
Mariner	25 ELH	25	2-Stroke	1987	27-414172
Mariner	25 M	25	2-Stroke	1985–1987	27-414172
Mariner	25 ML	25	2-Stroke	1985–1987	27-414172

Technical Specs

Product Type: Reed Block Gasket
Installation: Between reed block and intake assembly
Material: Gasket material (paper/composite)
Dimensions: 133.4 mm x 88.9 mm (5.25 in x 3.50 in)
Thickness: 1.27 mm (0.05 in)
Weight: 0.014 kg (0.03 lb)
OEM Part Number: 27-414172

What’s in the Box

1 x Gasket (Replaces 27-414172)

Installation Notes

Ensure the engine is off and cool, and disconnect the battery as a safety precaution.
Relieve any fuel system pressure and disconnect fuel lines or other components obstructing access to the reed block.
Carefully unbolt and remove the intake assembly and reed block.
Remove the old gasket. Be cautious not to scratch or damage the metal mating surfaces.
Thoroughly clean both the engine block and reed block surfaces, ensuring they are free of any old gasket material, oil, or debris.
Position the new gasket onto the reed block, aligning it with the bolt holes.
Reinstall the reed block and intake assembly. Tighten the bolts in a crisscross pattern to the manufacturer-specified torque to ensure an even seal.
Reconnect all components and check for any leaks before starting the engine.

Troubleshooting & FAQ

How do I know if this gasket will fit my engine?

This gasket is designed for specific Mercury and Mariner 18-25 HP 2-Stroke models from 1977–1988. Please use our detailed compatibility table on this page to verify your exact engine model and year before ordering.

What are the signs of a failed reed block gasket?

Symptoms of a bad reed block gasket include a rough idle, difficulty starting, loss of power, poor acceleration, and audible air-sucking sounds from the engine intake area. A leak can cause a lean fuel/air mixture, leading to poor performance.

Can I reuse the old gasket?

No. Gaskets are single-use components designed to compress and create a seal. Once removed, an old gasket will not provide a reliable seal and should always be replaced with a new one.

Do I need to apply sealant to this gasket?

Generally, this type of gasket is designed to be installed dry. However, always consult your engine's service manual for specific recommendations. In some cases, a very thin layer of non-hardening sealant may be recommended, but over-application can cause issues.

What's the difference between this part and older superseded numbers like 27-414171?

Superseded part numbers (like 41417 and 414171) were replaced by the manufacturer with the current number, 27-414172. This usually indicates a minor revision in material or design for improved performance. This aftermarket part is made to the specifications of the latest OEM number.

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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