Mercury – Quicksilver Exhaust Flapper Kit | Exhaust System Component | 4-Inch Through-Transom | 12644A1

Overview

Every boater knows that distinctive rumble of a through-transom exhaust — the sound that says your engine’s alive and breathing right. The Mercury Marine 12644A1 Quicksilver Exhaust Flapper Kit helps keep that performance sound crisp while protecting your system from unwanted backflow. Designed for 4-inch through-transom outlets, this flapper guards your exhaust path from water intrusion when you throttle down or shut off. It’s a small part with a big purpose: keeping your engine safe and your performance smooth, all while showing off that iconic Quicksilver “Q” logo.

Key Features

• Purpose: Prevents water from backing into the exhaust system during deceleration or when idling in rough water.
• Material: Constructed from heat-resistant, marine-grade rubber for flexibility and long-term durability.
• Fitment: Designed for 4-inch outside diameter through-transom exhaust outlets.
• Included: Comes with one flapper and a stainless steel clamp for easy installation.
• Design Detail: Features the Quicksilver “Q” logo, a nod to genuine Mercury Marine craftsmanship.
• Performance: Meets or exceeds OEM specifications for sealing, fit, and temperature resistance.

Engine & Boat Compatibility

• Fits 4-inch O.D. through-transom exhaust systems commonly found on MerCruiser-powered performance boats and cruisers.
• Works with a wide range of V6 and V8 marine engines equipped with Mercury or aftermarket exhaust systems.
• Designed for boats running Bravo, Alpha, or TRS sterndrives with through-transom setups.
• Suitable for both freshwater and saltwater use.

Performance & Practical Benefits

The flapper might seem like a simple piece of rubber, but it plays a critical role in keeping your engine protected. It seals tightly when water pressure pushes against it, keeping exhaust gases moving out and water from sneaking in. The result is smoother operation, quieter idling, and better long-term protection for your exhaust valves and manifolds.

Made from durable rubber and paired with a stainless clamp, it holds up under constant heat and exhaust flow. You’ll notice how well it stays seated, even after long runs at high speed or hours of cruising. It’s one of those small but vital parts that helps your system perform flawlessly while adding a bit of style with the Quicksilver logo.

Why Buy OEM

You can find cheaper flappers out there, but they often don’t fit quite right or last as long. The Quicksilver 12644A1 is built to Mercury Marine OEM standards, which means you’re getting the same fit and function as the original equipment. That tight seal, precise sizing, and heat resistance are what keep your exhaust running efficiently — and your engine safe from water damage.

With OEM parts, you’re not just buying a replacement — you’re restoring your system to factory performance. It’s a simple, affordable upgrade that helps keep your boat running strong and sounding right, season after season.

FAQ

Q1: What size exhaust outlets does this flapper kit fit?
It fits 4-inch outside diameter through-transom exhaust outlets.

Q2: What comes in the kit?
The kit includes one flapper and one stainless steel clamp for easy installation.

Q3: Can it be used in both freshwater and saltwater?
Yes — it’s designed for full marine exposure and resists corrosion and heat.

Q4: What makes this flapper better than aftermarket ones?
It’s an OEM Mercury Marine part, molded to exact tolerances and made from high-temp, marine-grade materials.

Q5: Is installation difficult?
Not at all. Most owners can install it in minutes with a screwdriver and basic tools.