Sierra 18-3671 Thermostat Kit, 142 Degree, Replaces Mallory 9-43154, Crusader 97361, GLM 13410, Pleasurecraft RP026002E

The Sierra 18-3671 Thermostat Kit is a complete replacement kit for marine engine cooling systems, providing everything needed to restore proper engine operating temperature in a single package. The kit is built around a 142 degree thermostat, which controls coolant flow so the engine reaches and holds its correct operating temperature for efficient combustion, reduced wear, and reliable performance on the water.

Rather than selling the thermostat alone, Sierra packages the 18-3551 thermostat together with the matching 18-0875 thermostat gasket, so the seal between the thermostat housing and the engine block is replaced at the same time as the thermostat itself. This is the recommended practice for any thermostat replacement, since reusing an old gasket can lead to coolant leaks or an improper seal even when the new thermostat is functioning correctly.

This kit is a direct equivalent for a number of OEM and aftermarket thermostat part numbers used across several marine engine and sterndrive brands, making it a convenient single-source replacement for boat owners and marine technicians who need to cross-reference an original part number to a current, available thermostat kit.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3671
• Product Type: Thermostat Kit
• Kit Contents: 18-3551 Thermostat, 18-0875 Thermostat Gasket
• Temperature Rating: 142 degrees
• Weight: 0.19 pounds
• UPC: 030999563095

Fitment

Fits marine engines and sterndrives that use the OEM thermostats listed below under Replaces (OEM).

Replaces (OEM)

• Crusader 97361
• GLM 13410
• Mallory 9-43154
• Pleasurecraft RP026002E

Frequently Asked Questions

What is included in the Sierra 18-3671 Thermostat Kit? The kit contains an 18-3551 thermostat and an 18-0875 thermostat gasket, so the thermostat and its sealing gasket are replaced together in one purchase.

What temperature is the 18-3671 thermostat rated for? The thermostat included in the Sierra 18-3671 kit is rated at 142 degrees, which is the temperature at which it opens to allow coolant to flow.

Does the 18-3671 kit include a gasket, or just the thermostat? It includes both: the 18-0875 thermostat gasket ships along with the 18-3551 thermostat inside the Sierra 18-3671 kit, so no separate gasket purchase is needed.

Is Sierra 18-3671 the same as Mallory 9-43154? Yes, Sierra 18-3671 is the direct cross-reference for Mallory part number 9-43154.

What OEM part numbers does the Sierra 18-3671 thermostat kit replace? This kit replaces Crusader 97361, GLM 13410, Mallory 9-43154, and Pleasurecraft RP026002E.

How much does the Sierra 18-3671 Thermostat Kit weigh? The complete kit weighs 0.19 pounds.

Is this a genuine Sierra part or an aftermarket copy? The 18-3671 kit is a genuine Sierra part, identified by Sierra part number 18-3671 and UPC 030999563095.

Will I need to replace the gasket separately when I install this thermostat? No, the Sierra 18-3671 kit already includes the 18-0875 thermostat gasket along with the 18-3551 thermostat, so both parts are replaced in the same job.

Can I use this thermostat kit on a Crusader or Pleasurecraft engine? Yes, the Sierra 18-3671 kit cross-references to Crusader 97361 and Pleasurecraft RP026002E, so it is a direct equivalent for engines that originally used those part numbers.

What is the UPC for the Sierra 18-3671 Thermostat Kit? The UPC for this kit is 030999563095.