Mercury – Plug for Flush Valves on FourStroke Outboards | Engine Cooling & Maintenance | Black Polymer Finish | 8M0215105

Overview

Every boater knows that peace of mind comes from the little things — the parts you barely notice because they just work. That’s exactly how the Mercury Plug for Flush Valves feels once it’s in place. You push off from the dock knowing your cooling system is sealed the way it should be, and that quiet confidence settles in before you even throttle up. It’s a small component, sure, but it plays a big role in keeping your engine running smooth whether you’re cruising across open water or idling back toward the ramp at sunset.

Key Features

• Direct-fit Mercury Marine part designed for engine flush valve ports
• Built from durable polymer materials tested for ultraviolet stability
• Designed for repeated use without warping or swelling
• Maintains a tight, secure seal in the cooling system
• Engineered for consistent performance across a wide range of operating temperatures
• Mercury Marine part number 8M0215105

Engine & Boat Compatibility

• Fits Mercury and Mercury Racing FourStroke outboards in the following ranges:
  • Seventy-five to one hundred fifteen horsepower two point one liter FourStroke (serial 2B094996 and up)
  • One hundred thirty-five to two hundred horsepower L4 Verado
  • One hundred thirty-five to one hundred fifty horsepower three point zero liter FourStroke
  • Two hundred to three hundred horsepower L6 FourStroke
  • Three hundred fifty to four hundred horsepower L6 FourStroke
  • One hundred seventy-five to two hundred twenty-five horsepower three point four liter V6 FourStroke
  • Two hundred to three hundred horsepower four point six liter V8 Verado and FourStroke
  • Three hundred fifty to four hundred twenty-five horsepower five point seven liter V10 Verado
  • Four hundred fifty to five hundred horsepower four point six liter V8 Race
• Commonly found on center consoles, bay boats, pontoons, bass boats and performance rigs running modern Mercury FourStroke power

Performance & Practical Benefits

A good flush valve plug doesn’t call attention to itself — it simply keeps water where it belongs. This one locks into place with a firm, reassuring feel, giving you a clean and complete seal every time you rinse the engine. The polymer construction won’t crack under sunlight or stiffen after seasons of use, which means you’ll get consistent performance year after year. When you’re flushing your engine after a long day in saltwater, the last thing you want is a loose or brittle plug. This one slides in smoothly, holds tight and helps your motor cool efficiently on the next trip. No fuss. No surprises.

Why Buy OEM

When it comes to small but essential components, sticking with a genuine Mercury Marine part is always the smart choice. You’re getting a plug engineered specifically for your outboard, tested under real marine conditions and built to withstand ultraviolet exposure, pressure changes and temperature swings. Aftermarket plugs may look similar, but they rarely match the long-term durability or exact fit that Mercury designs into its parts. With OEM, you avoid chasing down leaks or dealing with loose fittings. It’s the reliable, practical move — the kind a seasoned boater would recommend without hesitation.

FAQ

Q1: Which Mercury engines does the Plug 8M0215105 fit?

It fits a wide range of Mercury and Mercury Racing FourStroke outboards from seventy-five to five hundred horsepower, including Verado, V6, V8 and V10 models.

Q2: What makes this plug different from aftermarket alternatives?

You’re getting an exact fit and long-term durability that matches Mercury’s engineering standards. Aftermarket versions often fall short in sealing strength and material quality.

Q3: How do I know if this is the right replacement for my setup?

Check your engine’s serial range and model family. If it matches the compatibility list above, this is the correct Mercury Marine part.

Q4: Can this plug be used in both saltwater and freshwater?

Absolutely. The material is designed for both environments and resists ultraviolet exposure and corrosion.

Q5: Is installation straightforward?

Yes — it simply presses into the flush valve port and seats firmly. Most boat owners can replace it in seconds.