Sierra 18-2553-9 Thermostat Cover Gasket - Pack of 2, Replaces Mercruiser 27-47510, Fits MCM/MIE GM V-6 & V-8 Engines

The Sierra 18-2553-9 Thermostat Cover Gasket seals the thermostat housing on MCM/MIE GM V-6 and V-8 marine engines equipped with the older style two-piece thermostat housing. Sold as a pack of 2, this gasket ensures the housing forms a tight seal against the exhaust manifold or thermostat cover, preventing coolant leaks and maintaining proper engine operating temperature. It is built to Sierra's quality standard, which is designed to meet or exceed the original equipment part it replaces, giving boat owners a reliable, OEM-equivalent seal for routine thermostat service or replacement. This gasket is commonly needed whenever the thermostat cover is removed for cleaning, inspection, or thermostat replacement, since reusing an old gasket can lead to leaks. It directly interchanges with several OEM and aftermarket part numbers, making it easy to source a correct-fit replacement regardless of which brand's part number is printed on your old housing. Keeping a spare pack on hand is useful for owners who service their own MerCruiser sterndrive engines, since the gasket is inexpensive relative to the cost of a coolant leak or an engine that runs hot due to a failed seal.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2553-9
• Product Type: Thermostat Cover Gasket
• Package Quantity: 2
• Weight: 0.02 pounds
• UPC: 808282162870
• GTIN: 00808282162870
• Fitment: MCM/MIE GM V-6 & V-8 engines with older style 2-piece thermostat housing

Fitment

• 898 305 cid V-8, 1983-1984
• MCM/MIE GM V-6 & V-8 engines with older style 2-piece thermostat housing

Replaces (OEM)

• GLM 31460
• Mallory 9-60005
• Mercruiser 27-47510
• Mercruiser 27-47510Q
• Osco 47510

Frequently Asked Questions

What engines does the Sierra 18-2553-9 thermostat cover gasket fit? The 18-2553-9 fits MCM/MIE GM V-6 and V-8 marine engines that use the older style two-piece thermostat housing, including the 898 305 cid V-8 application built for 1983-1984.

How many gaskets come in a pack? Each Sierra 18-2553-9 package includes 2 thermostat cover gaskets, so you get a spare or enough for a two-sided housing in one purchase.

Is the 18-2553-9 gasket compatible with Mercruiser 27-47510? Yes, the Sierra 18-2553-9 thermostat cover gasket is interchangeable with Mercruiser 27-47510 and 27-47510Q, so it installs as a direct replacement for either of those OEM part numbers.

What other part numbers does this gasket cross-reference with? Besides the Mercruiser 27-47510 and 27-47510Q numbers, the 18-2553-9 also interchanges with GLM 31460, Mallory 9-60005, and Osco 47510.

Is this an OEM or aftermarket gasket? The 18-2553-9 is a Sierra aftermarket gasket manufactured to meet or exceed the specifications of the original equipment part it replaces.

How much does the 18-2553-9 gasket weigh? The Sierra 18-2553-9 thermostat cover gasket pack weighs 0.02 pounds.

When should I replace my thermostat cover gasket? A thermostat cover gasket like the 18-2553-9 should be replaced any time the thermostat housing is removed for service, since reusing the old gasket can allow coolant to leak from the seal.

Does the 18-2553-9 work with the newer style thermostat housing? No, the 18-2553-9 is designed for the older style two-piece thermostat housing on MCM/MIE GM V-6 and V-8 engines, not the newer housing designs.

What is the UPC for the Sierra 18-2553-9 gasket? The Sierra 18-2553-9 thermostat cover gasket has UPC 808282162870.

Can I use the 18-2553-9 gasket on a GM V-6 engine, not just V-8? Yes, the Sierra 18-2553-9 is listed to fit both GM V-6 and V-8 MCM/MIE engines with the older two-piece thermostat housing.