Powerhead Gasket Set – Fits Mercury/Mariner 45-50 HP 4-Cylinder (Replaces 27-72486A32)

$50.95 $81.00

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Powerhead Gasket Set – Fits Mercury/Mariner 45-50 HP 4-Cylinder (Replaces 27-72486A32) is backordered and will ship as soon as it is back in stock.

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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

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This Powerhead Gasket Set is engineered for Mercury/Mariner 45–50 HP, 4-cylinder, 2-stroke outboard engines produced from approximately 1968 to 1995. It provides the necessary seals for a complete engine powerhead overhaul.

It serves as a direct aftermarket replacement for GLM 39190, WSM 500-200, Sierra 18-4353, and OEM part number 27-72486A32.

Intended for complete engine rebuilds and overhauls.
Designed for 4-cylinder, 2-stroke cross-flow engines with a 2.565" bore.
Please note: This set does not include the cylinder head gasket.

Part Number Matrix

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

Brand	Part Number
Mercury/Mariner	27-72486A32
GLM	39190
WSM	500-200
Sierra	18-4353
Rareelectrical	27-72486A32

Engine & Model Compatibility

Confirm your engine model and year in the table below to ensure accurate fitment.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury	500	50	2-Stroke	1975	27-72486A32
Mercury	500, 50	50	2-Stroke	1976–1979	27-72486A32
Mercury	45 (4-cyl)	45	2-Stroke	1980–1986	27-72486A32
Mercury	45/50 HP	50	2-Stroke	1980–1986	27-72486A32
Mercury	45	45	2-Stroke	1980–1986	27-72486A32
Mercury	500	50	2-Stroke	1965–1967	27-72486A32	Made in USA, AUS, BEL, CAN

Technical Specs

Product Type: Powerhead Gasket Set
Application: Mercury/Mariner 45-50 HP 4-Cylinder outboard engines
Engine Type: 4-Cylinder, 2-Stroke, Cross Flow
Bore Size: 2.565"
Fuel Type: Gasoline
Installation: Engine rebuild/overhaul
Includes Head Gasket: No
Package Dimensions: 17.0" L x 14.0" W x 0.38" H

What’s in the Box

1 x Complete Powerhead Gasket Set (individual components are not itemized)

Installation Notes

Disconnect the battery and all fuel/electrical connections to the engine.
Perform necessary disassembly of the engine cowling and components to access the powerhead assembly.
Carefully remove the powerhead. Remove all old gasket material and meticulously clean all mating surfaces to ensure a perfect seal.
Position the new gaskets correctly according to your service manual's diagrams.
Reassemble the powerhead components and torque all fasteners to the manufacturer's specified sequence and values.
Reconnect all systems and perform a leak test before starting the engine.

Troubleshooting & FAQ

Does this set include the cylinder head gasket?

No, this particular powerhead gasket set does not include the cylinder head gasket. It is often sold separately as its replacement depends on the specific nature of the engine service being performed.

How can I tell if my powerhead gaskets need replacing?

Common signs of a failed powerhead gasket include loss of compression in one or more cylinders, visible water or oil leaks around the engine block, overheating, or water contamination in the engine oil.

Will this kit fit my Mercury 50 HP 3-cylinder engine?

No, this kit is specifically designed for the 4-cylinder, 2-stroke Mercury/Mariner engines listed in the compatibility table. It will not fit 3-cylinder models.

Is this a complete kit for a powerhead rebuild?

This is a complete gasket set for sealing the powerhead. A full rebuild may require additional components such as pistons, rings, bearings, and seals, which are not included in this kit.

What are the OEM vs. Aftermarket parts?

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.

What is the shipping speed & cost?

We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

What is the warranty & return policy?

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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