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Sierra 18-3012 Marine Neoprene Impeller with 6 Fins 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

118-3012
09/12/2036 6:50 AM
Sale Price

$21.76

3 left at this price

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Usually delivered within 2 days

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Fitment guaranteed

Product Details

The Sierra 18-3012 is a high-quality marine water pump impeller designed specifically for Mercury and Mariner outboard motors ranging from 3.5 HP to 9.8 HP. This critical cooling system component features durable neoprene construction with six flexible vanes molded around a brass hub, engineered to meet or exceed original equipment specifications.

Key Features:

  • 6-fin neoprene impeller construction for reliable performance
  • Brass hub for corrosion resistance and durability
  • Direct replacement for Mercury Marine part number 47-22748
  • Cross-compatible with Mallory 9-45308, GLM 89600, and Johnson Evinrude OMC 508388, 775465
  • Meets or exceeds OEM specifications for quality assurance
  • ISO 9001 certified manufacturing facility

Water pump impellers are essential for maintaining proper engine cooling in marine applications. The flexible vanes rotate on an eccentric within the pump housing, drawing water through the cooling system. Marine professionals recommend replacing impellers annually or every 100 hours of operation to prevent engine overheating and costly damage. Always keep a spare impeller on board for emergency replacements during extended boating trips.

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I had ordered some CM-19546-A2 (friction-modifier for posi-traction differentials with carbon-fiber clutches) from CJ Pony Parts, and it arrived broken and had all leaked out. I spent $25.42 for nothing, and they still have not responded to my complaint. I bought 2 bottles from THMotorsports in hopes that ONE would arrive undamaged. They arrived in a box, not a bubble mailer like CJ, and both bottles were intact and undamaged. If you're going to buy specialty automotive fluids online, THMotorsports is the better place to do so.

Only place that had my radiator in stock

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