Sierra 18-3644 Thermostat Kit, 160 Degree Thermostat with Cover Gasket, Replaces 807252T2

The Sierra 18-3644 Thermostat Kit is a complete engine cooling system kit built around a 160 degree Fahrenheit thermostat, giving boat owners everything needed to replace a worn or stuck-open thermostat in one purchase rather than sourcing the thermostat and gaskets separately. The kit bundles the Sierra 18-3649 thermostat (160 degree rating, cross-references to OEM 807252T2), the Sierra 18-2553 thermostat cover gasket (cross-references to OEM 27-47510), and the Sierra 18-2917 thermostat gasket, so the sealing surfaces are replaced along with the thermostat itself for a proper, leak-free reinstall.

Replacing the thermostat along with its gaskets in a single kit helps ensure the engine reaches and holds proper operating temperature, which protects against overheating and against running too cool, both of which can reduce engine efficiency and accelerate wear. Sierra manufactures its thermostats and gaskets to meet or exceed the specifications of the original equipment parts they replace, making this kit a straightforward like-for-like service part for marine stern drive and inboard engines that use a 160 degree thermostat with this cover gasket configuration.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3644
• Product Name: Thermostat Kit
• Temperature Rating: 160 degrees Fahrenheit
• Kit Contents: 18-3649 Thermostat (160 degrees F), 18-2553 Thermostat Cover Gasket, 18-2917 Thermostat Gasket
• Material: Metal
• Finish: Matte
• Color: White
• Weight: 0.16 pounds
• UPC: 808282105549

Fitment

Specific engine, HP, and model year fitment for the 18-3644 kit are not listed; the kit is defined by its 160 degree thermostat rating and matching cover gasket, so confirm your engine calls for a 160 degree thermostat with these components before ordering.

Replaces (OEM)

• 807252T2 (thermostat, replaced by Sierra 18-3649 in this kit)
• 27-47510 (thermostat cover gasket, replaced by Sierra 18-2553 in this kit)

Frequently Asked Questions

What is included in the Sierra 18-3644 Thermostat Kit? The kit contains three parts: the Sierra 18-3649 thermostat rated at 160 degrees Fahrenheit, the Sierra 18-2553 thermostat cover gasket, and the Sierra 18-2917 thermostat gasket, so both the thermostat and its sealing gaskets are replaced together.

What temperature rating is the thermostat in kit 18-3644? It is rated at 160 degrees Fahrenheit, which is the opening temperature stamped on the included Sierra 18-3649 thermostat.

Does the Sierra 18-3644 kit cross-reference to an OEM thermostat number? Yes, the 18-3649 thermostat included in the Sierra 18-3644 kit cross-references to OEM number 807252T2.

Is there an OEM equivalent for the thermostat cover gasket in this kit? The 18-2553 thermostat cover gasket included in the Sierra 18-3644 kit cross-references to OEM number 27-47510.

Do I need to buy the thermostat and gaskets separately? No, the Sierra 18-3644 kit bundles the thermostat and both gaskets (18-3649, 18-2553, and 18-2917) into a single purchase for a complete thermostat service.

How much does the Sierra 18-3644 Thermostat Kit weigh? The kit weighs 0.16 pounds.

What material is the thermostat housing or cover gasket made from? The components in the Sierra 18-3644 kit are made from metal with a matte finish.

Is the Sierra 18-3644 kit made by the original engine manufacturer or is it aftermarket? It is a Sierra-brand aftermarket kit manufactured to meet or exceed the specifications of the original equipment thermostat and gaskets it replaces, including OEM 807252T2 and 27-47510.

How do I know if my engine needs the 18-3644 kit versus a different Sierra thermostat kit? Confirm your engine specifies a 160 degree thermostat and uses a cover gasket matching OEM 27-47510; the Sierra 18-3644 kit is built around those two specifications.

What is the UPC for the Sierra 18-3644 Thermostat Kit? The UPC for the Sierra 18-3644 Thermostat Kit is 808282105549.

Can the gaskets in this kit be reused instead of replaced? The Sierra 18-3644 kit includes new 18-2553 and 18-2917 gaskets specifically so both sealing surfaces are replaced fresh alongside the 18-3649 thermostat rather than reusing old gaskets.