Sierra Water Jacket Cover Gasket 18-2573, Replaces 27-721421, Fits 6 Cyl. Mercury Outboard Engines, Pack of 2

The Sierra 18-2573 Water Jacket Cover Gasket is designed to seal the water jacket cover on 6 cylinder Mercury outboard engines, sealing the cooling passage against leaks between the cover and the engine block. A proper water jacket seal is essential to maintaining correct cooling system pressure and preventing coolant loss or overheating, so this gasket is a standard replacement item whenever the water jacket cover is removed for inspection, cleaning, or service. Each package contains 2 gaskets, giving you a spare on hand or enough for a job that calls for more than one. This part is sold under Sierra part number 18-2573 and cross-references directly to the original Mercury gasket numbers 27-721421, 27-72142, and 27-60475, so it installs as a direct replacement without modification. Keeping the correct gasket on hand simplifies routine water jacket cover maintenance and helps avoid downtime from a failed or hardened original gasket. Because gaskets compress and can lose their seal over time, replacing the water jacket cover gasket during any cover removal is good practice rather than reusing the old one.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2573
• Product Name: Water Jacket Cover Gasket
• Package Quantity: 2 gaskets per package
• Weight: 0.22 pounds
• UPC: 030999562753
• Category: Mercury Outboard Gaskets

Fitment

• 6 cylinder Mercury outboard engines

Replaces (OEM)

• 27-721421
• 27-72142
• 27-60475

Frequently Asked Questions

What does the Sierra 18-2573 gasket fit? The Sierra 18-2573 Water Jacket Cover Gasket fits 6 cylinder Mercury outboard engines, sealing the water jacket cover to the engine block.

What OEM numbers does 18-2573 replace? Sierra 18-2573 directly replaces Mercury gasket numbers 27-721421, 27-72142, and 27-60475.

How many gaskets come in a package of 18-2573? Each package of the Sierra 18-2573 Water Jacket Cover Gasket contains 2 gaskets.

How much does the 18-2573 gasket weigh? The Sierra 18-2573 Water Jacket Cover Gasket weighs 0.22 pounds per package.

Is Sierra 18-2573 a genuine Mercury part or an aftermarket equivalent? Sierra 18-2573 is an aftermarket gasket manufactured to match the dimensions and sealing performance of the original Mercury water jacket cover gasket, cross-referencing to Mercury numbers 27-721421, 27-72142, and 27-60475.

When should I replace the water jacket cover gasket? Any time the water jacket cover is removed from a 6 cylinder Mercury outboard for service or inspection, the gasket should be replaced with a new one such as the Sierra 18-2573 rather than reused, since a compressed or hardened gasket will not reseal properly.

What happens if the water jacket cover gasket fails? A failed water jacket cover gasket can allow coolant to leak from the sealing surface, which can lead to loss of cooling capacity and overheating in the 6 cylinder Mercury outboard it is installed on.

Does the 18-2573 gasket require sealant during installation? The Sierra 18-2573 Water Jacket Cover Gasket is installed at the water jacket cover mating surface as a standard replacement gasket for this application.

What is the UPC for the Sierra 18-2573 gasket? The UPC for the Sierra 18-2573 Water Jacket Cover Gasket is 030999562753.

Can I order just one gasket instead of the pack of 2? The Sierra 18-2573 Water Jacket Cover Gasket is sold as a package of 2 gaskets; it is not available as a single unit under this part number.