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Sierra 18-3650 Thermostat Kit for MerCruiser 3.0L Marine Engines

Manufacturer

Sierra

<h3>Sierra: Six Decades of Marine Aftermarket Excellence</h3><p><strong>Sierra</strong> has spent nearly 60 years earning its reputation as one of the most trusted names in the marine aftermarket industry. Originally focused on engine and drive components for boats, the brand has grown into a comprehensive source for nearly everything a boater needs to keep their vessel running at its best — from precision instrumentation to complete engine rebuild hardware.</p><p>Now operating as a brand of Dometic, Sierra manages global aftermarket distribution from a 300,000 sq. ft. facility in Litchfield, Illinois. The Sierra brand today encompasses not only its flagship marine parts line but also well-established marine names like Shields and Moeller, offering boaters a broader catalog than ever before. Whether you own an outboard, inboard, or sterndrive, Sierra's engineering team designs products to meet or exceed OEM specifications.</p><h3>Precision Instrumentation You Can Trust on the Water</h3><p>One of Sierra's most recognized product areas is its marine instrumentation lineup. The brand's <a href="/7570-sierra-gauge-set-1480">gauge sets</a> cover everything from classic analog instrument clusters to advanced digital multi-function displays. Sierra offers packages suited to outboards, sterndrives, and gasoline-powered inboards, with options ranging from coordinated analog kits in styles like Arctic, Eclipse, and Amega to modern touchscreen solutions like the R3 multi-function gauge. Features such as scratch-resistant domed glass lenses, silicone-dampened pointers, and perimeter backlighting make these instruments highly readable in all conditions.</p><p>Behind every accurate gauge reading is a properly calibrated sending circuit. Sierra's <a href="/7570-sierra-gauge-resistor-47908">gauge resistors</a> are a critical part of that chain, ensuring the signals from sensors and sending units are correctly interpreted by your instruments. These components are built to marine-grade standards to resist moisture, vibration, and corrosion — the realities of life on the water.</p><h3>Engine Internals Built to OEM Standards</h3><p>Sierra's history in marine power is perhaps best demonstrated by its deep catalog of engine components. The brand's <a href="/7570-sierra-engine-gasket-set-5404">engine gasket sets</a> cover a wide range of outboard and inboard applications and are engineered to deliver reliable seals in the demanding thermal and chemical environment of a marine engine. For boaters performing seasonal overhauls, top-end rebuilds, or full engine restorations, Sierra gasket kits are a go-to resource trusted by professional marine technicians and DIY boaters alike.</p><h3>A Complete Marine Parts Partner</h3><p>Beyond instrumentation and engine internals, Sierra's catalog spans fuel systems, electrical supplies, steering components, shore power, and more — all covered by what the brand calls an industry-leading warranty. Sierra also maintains a comprehensive parts-finder tool that enables cross-referencing with OEM part numbers from major manufacturers including Mercury, Yamaha, Suzuki, Volvo Penta, and others, making it straightforward to find the right replacement part for virtually any application.</p>

Part Number

18-3650
05/07/2036 10:45 AM
Sale Price

$27.23

In Stock (10+)

delivery box

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 18-3650 is a complete thermostat replacement kit designed for MerCruiser 3.0L marine engines. This kit provides everything needed for a proper thermostat service, ensuring optimal engine temperature regulation and reliable cooling system performance.

Kit Includes:

  • Thermostat (OEM# 59078)
  • Gasket (OEM# 27-47590-1)

Key Features:

  • Direct replacement for MerCruiser OEM parts
  • Marine-grade construction for saltwater and freshwater use
  • Complete kit eliminates need for separate gasket purchase
  • Manufactured by Sierra, a trusted name in marine engine parts

This thermostat kit helps maintain proper engine operating temperature, which is critical for engine longevity, fuel efficiency, and performance. Regular thermostat replacement is an essential part of marine engine maintenance and can prevent overheating or overcooling issues.

Good

Awesome!!!

I purchased a complete set of EBC usr sport rotors for my car. No other companies can come close to their pricing. AAAA+++++

Excellent! The shipping was faster then light and the part fit like a glove!

super service and best price on the net

Unbeatable price on the Internet, helpful customer service. But if you choose UPS ground, be aware that they do not ship out items during weekends. I'll definitely buy from them again.

Great price! Hopefully it delivers quickly as expected.

Your site is great, just the part I need.

Great Prices and great communication. I received notification as soon as I made the order, and when it was shipped out, along with a Tracking number. They were very quick to mail it out too.<br><br>Thanks<br><br>Order number 13029

A O.K

Lowest price I found and a great quick ordering experience. Product is listed as for WRX, but other sources say WRX model installs differently. Will work fine for my Forester, though.

Ordered Monday - didnt ship until Thursday.<br><br>Email sent tracking number, but didnt mention which source was used for transport.<br><br>Product as described.

Great

Fast shipping and email answered fast. I'll shop again. Tahnks

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