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Sierra 18-3647 Thermostat Kit for MerCruiser GM V6 V8 Engines 160°F

Manufacturer

Sierra

<p>For nearly six decades, Sierra has established itself as one of the marine industry's most trusted names in aftermarket engine and drive parts. Founded as a specialized marine parts manufacturer, Sierra has grown into a comprehensive supplier of replacement components, instrumentation, and accessories for both recreational and commercial boating applications. Operating from their 300,000-square-foot distribution center in Litchfield, Illinois, Sierra serves boat owners and marine technicians worldwide with an extensive catalog of parts engineered specifically for the harsh saltwater environment.</p><h3>Marine Engine Excellence</h3><p>Sierra's reputation was built on delivering precision-engineered internal engine components and drive system parts that meet or exceed OEM specifications. Their <a href="/7570-sierra-engine-gasket-set-5404">engine gasket sets</a> provide critical sealing solutions for inboard and outboard motors, while their <a href="/7570-sierra-engine-complete-assembly-15341">engine complete assemblies</a> offer comprehensive replacement options for major overhauls. Each component undergoes rigorous testing to ensure reliability in demanding marine conditions, from corrosion resistance to temperature cycling performance.</p><h3>Instrumentation and Monitoring Systems</h3><p>Accurate instrumentation is essential for boat operators to monitor engine health and prevent costly breakdowns on the water. Sierra's comprehensive line of <a href="/7570-sierra-gauges-200483">gauges</a> includes everything from fuel pressure and temperature indicators to voltmeters and trim gauges, all designed with marine-grade materials that withstand vibration, moisture, and UV exposure. Their <a href="/7570-sierra-tachometer-gauge-1488">tachometer gauges</a> deliver precise RPM readings critical for optimizing engine performance and fuel efficiency. Supporting these instruments, Sierra's <a href="/7570-sierra-gauge-resistor-47908">gauge resistors</a> ensure proper signal conditioning and accurate readings across various sensor types and engine configurations.</p><h3>Expanded Product Portfolio</h3><p>In 2022, Sierra significantly broadened its scope beyond traditional marine engine parts to encompass a wider range of boating accessories and even outdoor power equipment components. This strategic expansion brought established marine brands like Shields and Moeller under the Sierra umbrella, creating a one-stop resource for marine maintenance and replacement parts. The company now offers fuel systems, electrical components, battery charging solutions, and NMEA electronics alongside their traditional engine parts lineup.</p><h3>Quality Backed by Industry-Leading Warranties</h3><p>What sets Sierra apart in the crowded aftermarket marine parts market is their commitment to standing behind every component they manufacture. Their warranty coverage extends beyond simple part replacement—it includes shop labor, haul-out fees, towing charges, and related incidental costs should a warrantied part fail. This comprehensive protection reflects the company's confidence in their manufacturing processes and quality control standards. For boat owners facing repairs far from shore or mechanics working on customer vessels, this peace of mind is invaluable. Whether you're maintaining an outboard motor, rebuilding an inboard engine, or upgrading your boat's instrumentation, Sierra's decades of marine industry experience and commitment to quality make them a reliable choice for keeping your vessel running at peak performance.</p>

Part Number

118-3647
05/27/2036 11:17 PM
Sale Price

$26.02

In Stock (5)

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Usually delivered within 2 days

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No Hassle Returns

No Hassle Returns

Live-in-stock inventory

Live-in-stock inventory

Fitment guaranteed

Fitment guaranteed

Product Details

The Sierra 18-3647 Thermostat Kit is a complete replacement thermostat assembly designed for 1987 and newer GM-based MerCruiser engines with standard cooling systems. This premium aftermarket kit features a 160°F temperature rating and is engineered to meet or exceed OEM specifications for reliable engine temperature regulation.

Complete Kit Includes:

  • 18-3649 Thermostat (160°F)
  • 18-2844 Thermostat Cover Gasket
  • 18-2552 Thermostat Cover Gasket
  • 18-2553 Thermostat Cover Gasket
  • 18-7173 O-Ring
  • 18-2917 Thermostat Housing Gasket

This comprehensive kit eliminates the need to source individual components, providing everything required for a proper thermostat replacement in one package. A properly functioning thermostat is essential for maintaining optimal engine temperature, ensuring peak performance and fuel efficiency.

OEM Replacement Numbers: Mercury Marine 807252Q5, 807252T8, 8M0091470, 8M0109441 | Mallory 9-43157 | GLM 13101 | EMP 75-03222 | Pro Marine 64252K2

Seems to have worked so far

Great product and price. Customer service and communication above and beyond. Highly recommend.

I had a return that went very smoothly!

Great!

I had ordered some CM-19546-A2 (friction-modifier for posi-traction differentials with carbon-fiber clutches) from CJ Pony Parts, and it arrived broken and had all leaked out. I spent $25.42 for nothing, and they still have not responded to my complaint. I bought 2 bottles from THMotorsports in hopes that ONE would arrive undamaged. They arrived in a box, not a bubble mailer like CJ, and both bottles were intact and undamaged. If you're going to buy specialty automotive fluids online, THMotorsports is the better place to do so.

The tool I ordered came quickly, I've tested it out already, works great. Very pleased. Thanks!

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