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Sierra 18-2172 MerCruiser GM V6/V8 Engine Coupler Replaces 14505A2

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

18-2172
09/12/2036 7:01 AM
Sale Price

$364.51

3 left at this price

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Usually delivered within 2 days

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Product Details

The Sierra 18-2172 Engine Coupler is a heavy-duty aftermarket replacement coupler designed for MerCruiser stern drive applications. This coupler serves as the critical mechanical link between the GM inboard engine and the stern drive unit, transmitting power from the engine flywheel to the drive system.

This part is specifically engineered for use during engine upgrades or replacements — it is required when swapping an older GM V6 or V8 engine with a 2-piece rear main seal and a 3-1/2" crankshaft bolt pattern to a newer 1-piece rear main seal engine with a 3" crankshaft bolt pattern. Without this coupler, the bolt patterns of the old and new engine configurations are incompatible.

Key Features:

  • Direct replacement for MerCruiser OEM part number 14505A2
  • Designed for MCM GM V-6 and V-8 engines (305 and 350 cid)
  • Manufactured to meet or exceed original OEM specifications
  • Mounting hardware (studs, washers, and nuts) included
  • Cross-references: GLM 11520, Mallory 9-72500, OMC 775495

OEM Cross-Reference Part Numbers: MerCruiser 14505A2 | GLM 11520 | Mallory 9-72500 | OMC 775495

Sierra is the market-leading brand for aftermarket marine engine parts, offering a comprehensive product line backed by a customer satisfaction warranty covering parts and labor. This coupler is a dependable, cost-effective solution for any Pre-Vortec MerCruiser stern drive engine swap or rebuild.

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