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Sierra 18-3423 Marine Water Pump Base for Mercury/Mariner Outboard

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

18-3423
09/11/2036 3:54 PM
Sale Price

$34.88

2 left at this price

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Usually delivered within 2 days

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No Hassle Returns

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Fitment guaranteed

Fitment guaranteed

Product Details

The Sierra 18-3423 is a replacement water pump base designed for Mercury and Mariner outboard motors. This component serves as the structural foundation of the outboard's cooling system water pump assembly, providing a precise-fit mounting platform for the impeller and pump housing. Sierra manufactures this part to meet or exceed the quality of the original equipment it replaces.

Key Features:

  • Direct replacement for OEM Mercury Marine part number 46-73640A1
  • Meets or exceeds original equipment quality and specifications
  • Interchangeable with GLM 12020 and Mallory 9-15057 / 9-43301
  • Precision-molded for proper fit and sealing in the lower unit
  • Designed for use with Mercury and Mariner outboard lower units

OEM Cross-Reference:

  • Mercury Marine: 46-73640A1
  • GLM: 12020
  • Mallory: 9-15057, 9-43301

The Sierra 18-3423 water pump base is a critical component in maintaining proper engine cooling. Replacing a worn or damaged water pump base restores the integrity of the cooling system and helps prevent overheating. Sierra International is a trusted name in aftermarket marine parts, offering a broad range of replacement components engineered for reliability on the water.

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Autoplicity was quick and easy to order from. I found just what I was looking for in absolutely no time at all, plus it was shipped extremely quickly. I would definitely order from this site/company again.<br><br>Thanks!

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Quick and Easy

Great and Easy to Use Website

Very nice service

Excellent prices and fast shipping. Placing another order as I type. Great seller.

Quick and easy to purchase but took four days for the processing and to get shipped

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