Exhaust Water Shutter Kit – Fits MerCruiser 3.0-4.2L (Replaces 807166A3)

Exhaust Water Shutter Kit – Fits MerCruiser 3.0-4.2L (Replaces 807166A3)

This exhaust water shutter kit is designed for specific MerCruiser 3.0L, 3.6L, and 4.2L inboard and sterndrive engines manufactured between 1994 and 1997. It acts as a critical check valve, preventing water from flowing back up the exhaust system and into the engine.

This kit is a direct replacement for the following OEM and aftermarket part numbers: Mercury/MerCruiser 807166A3, Sierra 18-2732-9, GLM 89170, and Mallory 9-42802.

• Function: Acts as a flexible check valve to stop water from returning up the exhaust system to the engine.
• Installation: Designed for direct replacement of the original shutter.
• Package Contents: Includes two water shutters to service your engine.

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.

Technical Specifications

Package Contents

• 2 x Water Shutters (Replaces 807166A3)

Installation Guide

1. Safety First: Ensure the engine is completely cool and disconnect the battery before beginning work.
2. Locate Shutter Housing: Identify the exhaust Y-pipe or riser where the water shutter is located.
3. Access the Shutter: Carefully remove the exhaust hoses or elbow connected to the riser to gain access to the old shutter.
4. Remove Old Shutter: Take out the old, worn water shutter. Thoroughly clean the inside of the housing to remove any old rubber pieces or debris.
5. Install New Shutter: Insert the new shutter into the housing. Ensure it is oriented correctly to open for exhaust gases to exit while preventing water from entering.
6. Reassemble Components: Reinstall the exhaust elbow and hoses. Securely tighten all clamps and bolts to manufacturer specifications to prevent leaks.
7. Final Check: Reconnect the battery, start the engine, and carefully check for any exhaust or water leaks around the service area.

Troubleshooting & FAQ

Q: How do I confirm this fits my engine?
A: This kit is designed for MerCruiser 3.0L, 3.6L, and 4.2L engines from 1994-1997. To ensure compatibility, check your engine's model and serial number against the "Compatible Engine Models" table above. It directly replaces OEM part number 807166A3.

Q: What are the signs of a failing water shutter?
A: Common symptoms include a rattling sound from the exhaust at idle, water ingestion into the engine cylinders (which can cause hydrolock), difficulty starting, or finding visible rubber fragments in the exhaust water discharge.

Q: How often should I replace the exhaust water shutter?
A: We recommend inspecting the water shutters annually during routine maintenance. They should be replaced every 3-5 years, or immediately if you notice any signs of cracking, brittleness, or deterioration, especially for boats operated in saltwater.

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.