Cylinder Block Cover Gasket – Fits Mercury/Mariner 65-70 HP (Replaces 27-88449)

$7.89 $12.00

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Product Details

This high-quality aftermarket Cylinder Block Cover Gasket – Fits Mercury/Mariner 65-70 HP (Replaces 27-88449) is designed for 3-cylinder outboard engines from 1972 to 1983. It provides a reliable seal to maintain engine performance and prevent leaks.

It serves as a direct cross-reference for multiple OEM and aftermarket part numbers, including Mercury 27-88449, 27-74511, Sierra 18-2504, and GLM 32090, ensuring a precise fit for compatible models.

Installs as a direct replacement part.
Crafted from durable gasket material for a long-lasting seal.
Engineered to meet or exceed original equipment specifications.

Part Number Matrix

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

Brand	Part Number
Mercury	27-88449
Mercury	88449
Mercury	27-74511
Mercury	27-60310
Mercury	27-76401
Sierra	18-2504
GLM	32090

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury/Mariner models, compatibility is often determined by serial number. Please verify your engine's serial number falls within the specified ranges.

Brand	Model	Rated HP	Years	OEM Part No.	Notes
Mercury	Outboard	65	1972–1983	27-88449	s/n 3293184-4571651
Mercury	650	65	1975	27-88449	s/n 3547987-4382056
Mercury	650	65	1976	27-88449	s/n 4382057-4571651
Mercury	Outboard	70	1977–1979	27-88449	s/n 4571652-5579016
Mercury	Outboard	70	1980, 1982–1983	27-88449	s/n 5579017-6428680, s/n 5702220-6428680, s/n 7145938-7208332, s/n 7177688-7208332, s/n 8065065 & up, s/n 6255131-9385910

Technical Specs

Product Type: Cylinder Block Cover Gasket
Installation: Direct replacement
Material: Gasket material
Dimensions: 13.0" H x 10.0" W x 0.13" L
Warranty: 1 year (from PARTSDEPOT)

What’s in the Box

1 x Cylinder Block Cover Gasket (27-88449)

Installation Notes

Ensure the engine is off, cool, and disconnected from the power source and fuel supply.
Carefully access and remove the old cylinder block cover and its gasket. Note the orientation of all components.
Thoroughly clean both the engine block and cover mating surfaces. Ensure they are completely free of old gasket material, oil, and debris.
Carefully align and position the new gasket onto the cylinder block. No sealant is typically required, but consult your service manual.
Reinstall the cover and tighten the bolts in the sequence and to the torque values specified by the manufacturer's service manual to ensure an even seal.

Troubleshooting & FAQ

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

The most reliable method is to match your engine's serial number to the ranges listed in the "Engine & Model Compatibility" table. You can also compare your old part's number to those in the "Part Number Matrix."

What are the signs of a failed cylinder block cover gasket?

Common symptoms include external oil or water leaks around the cover, engine overheating, poor performance, or visible damage to the old gasket upon inspection.

Do I need to use sealant with this gasket?

Most modern gaskets of this type are designed for dry installation. Using sealant can sometimes interfere with a proper seal. Always refer to your engine’s official service manual for instructions specific to your model.

What's the difference between this and an OEM gasket?

This is an aftermarket part designed to meet or exceed OEM specifications for fit and function. It offers comparable performance and durability at a more accessible price point.

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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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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