Exhaust Water Shutter Assembly - Fits MerCruiser Diesel 3.0L, 3.6L, 4.2L Engines (Replaces 807166A3)

Exhaust Water Shutter Assembly – Fits MerCruiser Diesel 3.0L, 3.6L, 4.2L Engines (Replaces 807166A3)

This exhaust water shutter assembly is designed for MerCruiser Diesel 3.0L, 3.6L, and 4.2L engines (1992–1995). It features the correct butterfly-style water flapper design required for the exhaust Y-pipe, preventing water from entering the engine through the exhaust system while allowing exhaust gases to exit.

This component is a direct replacement for Mercury Marine part 807166A3, Sierra 18-2732-9, and GLM 89170.

• Engineered for direct fitment to the exhaust Y-pipe.
• Compatible with diesel fuel applications.
• Installation is a simple press-fit process using the included rubber grommets.

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.

Technical Specifications

Package Contents

• 2 x Exhaust Shutter Assembly (Replaces 807166A3)
• 4 x Rubber Grommets (Attachment Pins)

Installation Guide

1. Ensure the engine is completely cool before beginning. Locate the exhaust Y-pipe where the old shutters are situated.
2. Carefully pry out and remove the old, deteriorated shutter assemblies along with their rubber grommets.
3. Thoroughly clean the mounting surface inside the Y-pipe to remove any debris or residue.
4. Insert the new rubber grommets into the pre-drilled holes on each of the new shutter assemblies.
5. Align the new shutter assembly inside the Y-pipe housing, ensuring the flapper is oriented correctly to open outwards.
6. Firmly press the grommet pins into the corresponding holes in the Y-pipe until the shutter clicks securely into place.
7. Manually check that both butterfly flaps can move freely without any obstruction or binding. Repeat for the second shutter.

Troubleshooting & FAQ

How do I confirm this fits my engine?
This shutter assembly is designed exclusively for MerCruiser Diesel 3.0L, 3.6L, and 4.2L engines made between 1992 and 1995. To guarantee fitment, please verify your engine model and year against our "Compatible Engine Models" list and ensure your current part number matches one of the cross-references provided, such as 807166A3.

What are the symptoms of a failing water shutter?
Common signs include engine overheating at idle speeds, a gurgling sound from the exhaust, or back-pressure issues. Visually, you may find the old shutters are cracked, broken, or missing entirely, which can lead to water ingestion and catastrophic engine damage.

Is this sold as a single item or a complete set?
This product is sold as a complete set. Each package contains two shutter assemblies and four rubber grommets, which is everything required to service one engine exhaust Y-pipe.

OEM vs. Aftermarket?
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.

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

What is your warranty and return policy?
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.