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Sierra 18-3681 Volvo Penta Marine Engine Thermostat

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

18-3681
08/07/2036 6:29 AM
Sale Price

$83.10

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Product Details

The Sierra 18-3681 is a direct-replacement marine engine thermostat engineered for Volvo Penta diesel inboard engines, including the D4, D6, and D12 series. Operating at a rated temperature of 180°F (82°C), this thermostat helps maintain optimal engine operating temperature for reliable, efficient performance on the water.

Sierra designs this thermostat to meet or exceed OEM specifications, providing a dependable, cost-effective alternative to the factory part. It is a direct interchange for Volvo Penta OEM part number 8149182, as well as cross-references 1303061, 1676306, 1544683, and 1661277.

Key Features:

  • Temperature rating: 180°F / 82°C
  • Direct OEM replacement — interchangeable with Volvo Penta 8149182
  • Also cross-references: 1303061, 1676306, 1544683, 1661277
  • Designed for Volvo Penta D4, D6, and D12 diesel inboard engines
  • Meets or exceeds OEM specifications for fit, form, and function
  • Manufactured by Sierra International, a trusted name in marine engine parts

Sierra International has decades of experience producing high-quality marine engine and drive components. The 18-3681 thermostat is built to withstand the demanding conditions of marine environments, ensuring accurate temperature regulation that is critical for long engine life and peak performance.

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