Sierra Spark Plug Wire Set 18-28085 for Mercury Outboard Engines

The Sierra 18-28085 Spark Plug Wire Set is a copper-core ignition wire set built for Mercury outboard engines. Each wire carries the ignition spark from the coil or distributor to the spark plug, and consistent, low-resistance delivery is critical for reliable starting, smooth idle, and full power output on the water. Sierra builds this set with a copper core and copper top material, matching the conductive properties expected of marine-grade ignition wiring, and it is designed as a universal fit across the outboard applications it covers rather than a single narrow application.

This is a complete set (one unit count) intended as a direct replacement for a worn, cracked, or misfiring wire set, and it carries Sierra's standard limited warranty. Because ignition wires age from heat cycling and vibration, replacing the full set at once rather than one wire at a time helps keep resistance and timing consistent across all cylinders. The 18-28085 is intended for watercraft use and is sold as a universal-fit wire set rather than being restricted to one specific engine block or horsepower rating.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-28085
• Core Material: Copper
• Top Material Type: Copper
• Vehicle Service Type: Watercraft
• Automotive Fit Type: Universal Fit
• Unit Count: 1 Count
• Included Components: Wire Set
• Weight: 0.68 pounds
• UPC: 808282341442

Fitment

Mercury outboard engines (universal fit; no specific horsepower, year, or model restriction is specified).

Frequently Asked Questions

What engines does the Sierra 18-28085 spark plug wire set fit? The 18-28085 is a universal-fit wire set intended for Mercury outboard engines; no specific horsepower or model range is specified for it, so it is not limited to one engine block.

How many wires come in the 18-28085 set? This is sold as one complete set (unit count of 1), covering the full wire set rather than an individual replacement wire.

What material is the conductor made of? Both the core and the top material of the Sierra 18-28085 wire set are copper, which provides low-resistance conduction for reliable spark delivery.

Is this a genuine Sierra part or an aftermarket copy? The 18-28085 is a Sierra-branded spark plug wire set, manufactured by Sierra International with its own limited warranty coverage.

How much does the 18-28085 wire set weigh? The Sierra 18-28085 spark plug wire set weighs 0.68 pounds.

Why replace the whole wire set instead of a single wire? Replacing all wires together, as with the 18-28085 set, keeps resistance and spark delivery consistent across every cylinder instead of leaving older, higher-resistance wires mixed in with a new one.

Is the 18-28085 set intended for marine or automotive use? It is listed for watercraft use, making it a marine ignition wire set rather than an automotive-specific product.

Does the 18-28085 come with a warranty? Yes, the Sierra 18-28085 wire set includes Sierra's standard limited warranty.

What is included in the box with part number 18-28085? The package includes the complete spark plug wire set only, listed under the included components as Wire Set.

Will the 18-28085 fit any outboard, or only certain horsepower ranges? It is designated a universal fit for Mercury outboard engines, with no specific horsepower or year range stated in its specifications.