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Sierra 18-3673 Thermostat Kit for Johnson/Evinrude V4 V6 Crossflow Outboards

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

18-3673
05/07/2036 10:44 AM
Sale Price

$40.80

In Stock (10+)

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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 18-3673 Thermostat Kit is a complete cooling system service kit designed for Johnson and Evinrude V4 and V6 Crossflow outboard engines. This comprehensive kit includes all the essential components needed to service your outboard's thermostat system in one convenient package.

Kit Includes:

  • Thermostat
  • Thermostat cover gasket
  • Thermostat gasket
  • Grommet (V4 Crossflow)
  • Poppet relief valve (V4 Crossflow)
  • Valve spring (V4/V6 Crossflow)

Proper thermostat function is critical for maintaining optimal engine operating temperature and preventing overheating. This Sierra kit provides OEM-quality replacement components to restore reliable temperature regulation to your outboard's cooling system. Regular thermostat maintenance helps extend engine life and ensure consistent performance on the water.

Application: Fits Johnson/Evinrude V4 and V6 Crossflow outboard engines

Been good although I never got a response about the wrong gaskets in my last order.

I hope it fits properly

Great price and fast shipping! Tech support helped me before the sale to make sure I was ordering the right part

very good

Easy to find and price was good. The product fit well. Works well so far

Quick shipping, and great prices. Thanks Autoplicity!

Easy to order!

Easy transaction.

Quick and easy checkout process...

i was skeptical about this site but after reading the reviews and them having the lowest price i could find for my part i pulled the trigger and wasn't disappointed. fast shipping and low prices with great customer service will shop with them again if they have what im looking for.

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