Mercury – Quicksilver Water Shutter | For Select MerCruiser Sterndrive Engines | 807166A3

Overview

When the water gets rough, your engine needs protection from the backflow that can sneak up the exhaust system. The Mercury Marine 807166A3 Quicksilver Water Shutter—sometimes called a water flapper—does exactly that. Designed for various MerCruiser sterndrive engines, this simple but vital part closes automatically when the engine is shut off or idling to stop water from washing back into the cylinders. It’s durable, reliable, and built to handle years of exposure to exhaust heat and saltwater — a quiet safeguard that keeps your motor safe and running strong.

Key Features

• Purpose: Prevents water from backing up into the exhaust system when idling or shut off.
• Design: Functions as a flexible check valve — opens for exhaust flow, closes against backwash.
• Fit: 2.5-inch diameter at the hinge pin; installs inline within the exhaust system.
• Durability: Made from heat- and corrosion-resistant materials for long service life.
• Placement: Mounts downstream of the flexible union between the elbow and Y-pipe.

Engine & Boat Compatibility

• Fits various MerCruiser sterndrive installations (check owner’s or service manual for exact fitment).

Performance & Real-World Benefits

The 807166A3 water shutter quietly protects your MerCruiser engine every time you shut it down. When the boat is stopped or reversing in waves, this flapper closes to stop seawater from being forced back up the exhaust system — protecting the engine from corrosion, internal rust, or hydro-locking.

Made from high-strength materials, this shutter is built to handle the punishing mix of heat, moisture, and vibration that comes with marine exhaust systems. It installs quickly, fits snugly, and once it’s in place, you won’t have to think about it — just enjoy the confidence that comes with knowing your engine is safe.

Why Choose Mercury OEM

The Quicksilver 807166A3 is a genuine Mercury Marine part, engineered for precision fit and lasting reliability. Generic replacements can use cheaper plastics or rubber that harden, crack, or warp from exhaust heat, which can cause early failure and potential engine damage.

Mercury’s OEM design is built to handle real-world marine conditions, providing consistent performance and protection over time. It’s the same part Mercury installs on new sterndrives — tested, proven, and trusted by professionals worldwide.

FAQ

Q1: What does a water shutter do?
It prevents water from flowing backward through the exhaust system into the engine during idling, reversing, or when shut off.

Q2: What’s the size of this shutter?
It measures 2.5 inches in diameter at the cross pin (hinge).

Q3: Where is it installed?
Inside the exhaust system, downstream of the flexible union between the elbow and Y-pipe.

Q4: When should I replace it?
Replace it if it’s cracked, stiff, or missing, or during exhaust maintenance intervals.

Q5: Why OEM instead of aftermarket?
Because Mercury OEM shutters are made from high-temp, corrosion-resistant materials that hold up under the real stresses of boating — ensuring long-lasting engine protection.