Heurofosh Exhaust Flapper Kit 807166A1 for MerCruiser V6 V8 — 2 metal/rubber flappers with grommets, OEM-fit anti-backflow

The Heurofosh 807166A1 Exhaust Flapper kit is a direct-fit replacement set of two marine exhaust flappers engineered to stop lake water backflow and restore proper exhaust sealing on compatible MerCruiser V6 and V8 stern drive engines.

Replace worn or damaged exhaust flappers with this OEM-quality kit designed specifically for MerCruiser V6 and V8 engines that use the 807166A1-style shutter. Built from metal and rubber, the two flappers and included grommets aim to provide long-lasting resistance to corrosion and heat typical of marine environments. This product listing clarifies compatibility limits and installation notes so you can get the correct part the first time.

Which MerCruiser engines will this 807166A1 kit fit?

This kit fits many MerCruiser V6 and V8 stern drive models that use the 807166A1-style water shutter flapper. It is not universal: some V6s with one-piece manifolds and some early V8s with a round pin-through flapper require a different part.

• Includes two flappers plus four rubber grommets—part number 807166A1.
• Not compatible with V6 engines that use one-piece manifolds—those require 807166A2.
• Doesn’t fit early V8s that use a round pin-through flapper design.
• Check your current flapper shape and mounting pin style before ordering.

How does installing these exhaust flappers affect engine protection?

These flappers help reduce the chance of lake water being drawn into the exhaust when the engine is shut down hot, protecting internal components and exhaust passages. They act as a simple mechanical shutter that closes when flow stops, minimizing reverse water entry.

• Prevents unwanted water backflow into manifolds and risers.
• Helps reduce corrosion risk by limiting water contact with metal parts.
• Maintains correct exhaust sealing for quieter, more efficient operation.

What materials and build quality should I expect from the Heurofosh kit?

The kit combines durable metal for structural support with rubber grommets for a resilient, vibration-tolerant seal. Heurofosh aims to match OEM specs so fit and function closely resemble factory components.

• Metal flapper blades resist heat and maintain shape under typical marine conditions.
• Rubber grommets provide cushioning and a water-tight seat for the shutter pin.
• Sold as a two-piece kit to replace both flappers simultaneously for balanced operation.

Is installation difficult and what should I know before fitting?

Installation is straightforward for anyone comfortable with basic stern drive maintenance; the kit is designed for direct replacement using your existing mounting hardware. Always verify compatibility and follow safe procedures—work with a cool engine and proper supports.

• Remove old flappers and inspect mounting pin and manifold for wear.
• Fit new rubber grommets, slide flappers into position, and secure per factory orientation.
• Test with a brief engine run to confirm correct movement and sealing.

Who is this for: The Heurofosh 807166A1 Exhaust Flapper kit is intended for boat owners, marine mechanics, and restoration specialists who operate MerCruiser V6 or V8 stern drive engines that match the 807166A1 shutter design. If you need an OEM-quality replacement to reduce water backflow risk and restore reliable exhaust shutter function—but please verify manifold and pin style before purchase—this kit provides a durable, straightforward solution.