Water Shutter Kit – Fits MerCruiser V6/V8 Stern Drives (Replaces 807166A3)

Water Shutter Kit – Fits MerCruiser V6/V8 Stern Drives (Replaces 807166A3)

This aftermarket water shutter and bellows kit is engineered for MerCruiser stern drive engines equipped with 4-inch exhaust systems, covering most V6 and V8 models from approximately 1982 through 1996. It serves as a direct replacement to prevent water from backing up into the engine through the exhaust.

This kit directly replaces Mercury/MerCruiser part numbers 807166A3 and 807166A1; Sierra 18-2732-9; GLM 89170; and Mallory 9-42802.

• Function: The two-piece "clapper" design prevents water ingestion into the engine.
• Installation Location: Mounts inside the exhaust Y-pipe.
• Complete Kit: Includes shutters, upper and lower bellows, and all necessary clamps for a full replacement.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

MerCruiser Sterndrive Models

MerCruiser Inboard Models

Technical Specifications

Package Contents

• 2 x Water Shutters/Flappers (Replaces 807166A3)
• 2 x Lower Exhaust Bellows (Replaces 32-14358T / 32-14358001)
• 2 x Upper Exhaust Bellows (Replaces 32-44348T / 32-44348001)
• 4 x Stainless Steel Clamps

Installation Guide

1. Safety First: Begin by disconnecting the boat's battery to prevent any accidental starts.
2. Access the Stern Drive: Depending on your boat's configuration, gain access to the stern drive's exhaust components.
3. Remove Old Bellows: Loosen the clamps and carefully remove the old upper and lower exhaust bellows.
4. Remove Old Shutters: Extract the old, worn water shutters from the exhaust Y-pipe. Take note of their orientation.
5. Clean Surfaces: Thoroughly clean the Y-pipe and exhaust tube surfaces where the new bellows will be seated.
6. Critical Fitment Check: This kit will not work on V6 engines with one-piece manifolds or early V8 models with a round pin going through the flapper. Verify your system before proceeding.
7. Install New Shutters: Insert the new water shutters into the Y-pipe, ensuring they are correctly oriented and can move freely.
8. Install New Bellows: Fit the new upper and lower bellows into position and secure them tightly with the new stainless steel clamps.
9. Final Check: Re-connect the battery. Start the engine and check for any exhaust leaks around the new bellows.

Troubleshooting & FAQ

Q: How do I know if this kit fits my MerCruiser engine?

A: This kit is designed for MerCruiser V6 and V8 stern drives from 1982-1996 with a 4-inch exhaust system. Please check the compatibility tables on this page to confirm your specific model and year. It is crucial to note this will not fit V6 engines with one-piece exhaust manifolds or early V8 models that use a round pin through the flapper.

Q: What is the purpose of the "water shutter" or "flapper"?

A: The water shutter is a critical component in your exhaust system that prevents water from flowing back into the engine cylinders when the engine is off or at idle. A functioning shutter protects your engine from catastrophic water damage.

Q: What are signs that my old water shutters have failed?

A: Common signs of failure include rattling noises from the exhaust at idle, engine overheating, or difficulty starting. Upon visual inspection, you might find the old shutters are broken, brittle, missing pieces, or have fallen into the exhaust pipe.

Q: OEM vs. Aftermarket?

A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?

A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?

A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.