Water Shutter Assembly – Fits MerCruiser V6/V8 (Replaces 807166A1, 807166A2)
Water Shutter Assembly – Fits MerCruiser V6/V8 (Replaces 807166A1, 807166A2) is backordered and will ship as soon as it is back in stock.
Couldn't load pickup availability
Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Water Shutter Assembly – Fits MerCruiser V6/V8 (Replaces 807166A1, ...
Product Details
This Water Shutter Assembly is a crucial replacement part designed to prevent water from flowing back into the engine through the exhaust system. It is engineered for a precise fit on MerCruiser V6 and V8 engines (including 4.3L, 5.0L, and 5.7L models) manufactured from 1996 to the present, specifically those equipped with a 'Y-pipe' and two-piece exhaust manifold configuration.
This assembly is a direct interchange for MerCruiser part numbers 807166A1, 807166A2, and the complete kit 807166A3.
- Installs in the exhaust Y-Pipe assembly.
- Made from durable rubber with a steel reinforcement rod.
- Includes essential grommets for a complete drop-in installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| MerCruiser | 807166A1 | Individual shutter or part of a kit. |
| MerCruiser | 807166A2 | Superseded version; may be identical or have minor revisions. |
| MerCruiser | 807166A3 | Designates a kit including the shutter and grommets. |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | 4.3L V6 | Various | 4-Stroke | 1996+ | 807166A1/A2 | With Gen+ engines and 2-piece manifold. |
| MerCruiser | V6 & V8 | Various | 4-Stroke | 1996+ | 807166A1 | Gen+ with larger Y-pipe. |
| MerCruiser | Alpha/Bravo | Various | 4-Stroke | 1996+ | 807166A1 | Must match Y-pipe model. |
Technical Specs
- Product Type
- Exhaust Water Shutter Assembly
- Installation
- Y-Pipe
- Fuel Type
- Gasoline
- Connection
- Drop-in with grommets
- Housing Material
- Rubber with steel rod
- Housing Color
- Black
- Fitting Type
- Drop-in
- Other Technical Attributes
- Prevents water backflow into engine; failure can result in engine hydrolock
What’s in the Box
- 1 x Water Shutter Assembly (Replaces 807166A1/807166A2)
- 2 x Grommets (Replaces 25-8M0204688)
Installation Notes
- Disconnect the boat's battery for safety.
- Gain access to the exhaust Y-pipe where it connects to the transom assembly.
- Carefully remove the exhaust bellows or hose connected to the Y-pipe to expose the old water shutter.
- Extract the old water shutter and its grommets. Note their orientation.
- Thoroughly clean the mounting surfaces inside the Y-pipe, removing any debris or old sealant.
- Insert the new grommets into the Y-pipe, followed by the new water shutter. Ensure it is seated correctly and can move freely.
- Reconnect the exhaust components and tighten all clamps to manufacturer specifications.
- Reconnect the battery and test the engine, checking for exhaust leaks.
Troubleshooting & FAQ
How do I know if my water shutter has failed?
Common signs of a failed water shutter include a rattling or clanking noise from the exhaust at idle, backfiring, or visible pieces of rubber in the exhaust stream. During inspection, a damaged, brittle, or missing shutter indicates it needs immediate replacement.
What happens if a faulty water shutter is not replaced?
A missing or broken shutter allows water to flow backward into the exhaust manifolds and potentially into the engine cylinders when the engine is shut off or operating at low RPMs. This can cause catastrophic engine damage known as hydrolock.
Is this the shutter only, or a full kit?
This is a complete kit that includes both the water shutter itself and the two required mounting grommets, allowing for a full replacement.
How can I confirm this fits my specific engine?
This part fits a wide range of MerCruiser V6 and V8 engines made from 1996-onward that use a Y-pipe. The best way to confirm is to match your existing part number to 807166A1 or 807166A2, or visually compare your old part to our product photos.
What is the difference between part numbers 807166A1, A2, and A3?
807166A1 and 807166A2 are part numbers for the shutter itself; the 'A2' often represents a minor revision or a different supplier but is functionally identical. The number 807166A3 typically refers to the complete kit, which includes the shutter and grommets.
Are special tools required for installation?
Standard marine mechanic's tools, such as socket wrenches and screwdrivers for hose clamps, are generally sufficient. Accessing the Y-pipe can be challenging depending on the boat's configuration.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
