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Sierra 18-3646 Thermostat Kit 142 Degree Mercruiser

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

118-3646
05/27/2036 10:15 PM
Sale Price

$21.77

In Stock (8)

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Usually delivered within 2 days

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Product Details

The Sierra 18-3646 is a complete thermostat kit designed for Mercruiser stern drive marine engines. This kit features a 142-degree thermostat and includes all necessary gaskets for a complete installation. Engineered to meet or exceed OEM specifications, this kit replaces Mercury Marine part number 807252Q3.

Application:

  • For use with 1982 and older Ford and GM V-8 marine engines with standard cooling
  • Compatible with 1996 and older high-performance models
  • Designed for engines with closed cooling systems

Complete Kit Includes:

  • (1) 18-3551 Thermostat - 142 degrees
  • (1) 18-2917 Thermostat Housing Gasket
  • (1) 18-2844 Thermostat Cover Gasket
  • (1) 18-2553 Thermostat Cover Gasket
  • (1) 18-2834 Thermostat Cover Gasket

OEM Cross-References: Mercruiser 807252Q3, 807252T6, GLM 13380, Mallory 9-43151

Sierra Marine replacement parts are manufactured to meet the demanding requirements of marine environments, providing reliable performance and durability for your boat's cooling system.

It was gr8 and convinced

First time ordering from here. Seems to be a good company. The part was decently priced. Shipping was super fast. It was expensive but worth it in the end because I needed the part before a tournament

If my order is delivered and is correct part all is good

Very smooth

Great

Very good service, got my seats on Saturday after ordering on Wednesday. Very good quality. Very pleased.

Fast shipping

Easy to order!

Good price,good product , customer service was on the ball, but shipping took a little bit

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