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) is backordered and will ship as soon as it is back in stock.
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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.).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Exhaust Water Shutter Assembly – Fits MerCruiser Diesel 3.0L, 3.6L,...
Product Details
This Exhaust Water Shutter Assembly is designed for MerCruiser Diesel engines including the 3.0L, 3.6L, and 4.2L series models manufactured between 1992 and 1995. It features a butterfly-style water flapper design that provides a direct-fit replacement for the exhaust Y-pipe, preventing water from entering the engine through the exhaust.
It serves as a direct replacement for Mercury Marine 807166A3, Sierra 18-2732-9, and GLM 89170.
- Installs directly into the Y-pipe exhaust assembly.
- Designed for diesel fuel applications.
- Package includes two shutter assemblies and four grommets.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury Marine | 807166A3 |
| Sierra | 18-2732-9 |
| GLM | 89170 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| MerCruiser | D3.0L D-Tronic | 150 | 4-Stroke | 1992–1995 | 807166A3 |
| MerCruiser | D3.6L | 170 | 4-Stroke | 1992–1995 | 807166A3 |
| MerCruiser | D4.2L | 200 | 4-Stroke | 1992–1995 | 807166A3 |
| MerCruiser | D4.2L D-Tronic | 225 | 4-Stroke | 1992–1995 | 807166A3 |
Technical Specs
- Product Type
- Exhaust Water Shutter Assembly / Flapper
- Installation
- Direct fit to Y-pipe exhaust
- Fuel Type
- Diesel
- Connection
- Press-fit with rubber grommets
- Housing Material
- Rubber with internal steel support rod
- Housing Color
- Black
- Dimensions
- 4" (101 mm) diameter shutter width
- Fitting Type
- Butterfly-style hinge
- Other Technical Attributes
- Set of 2 shutters per part number
What’s in the Box
- 2 x Exhaust Shutter Assembly (807166A3)
- 4 x Rubber Grommets (attachment pins)
Installation Notes
- Disconnect the battery and ensure the engine is cool.
- Locate the exhaust Y-pipe assembly where the shutters are housed.
- Carefully remove the old, worn shutters and their grommets. This may require prying them out.
- Thoroughly clean the shutter housing and grommet holes, removing any debris or corrosion.
- Press the new rubber grommets firmly into the designated holes in the Y-pipe.
- Align the pins on the new shutter assemblies with the grommets and press them firmly into place.
- Ensure each shutter can move freely without binding.
- Reconnect the battery and test run the engine to check for proper exhaust flow and no water leaks.
Troubleshooting & FAQ
How can I confirm this shutter fits my engine?
This part fits MerCruiser Diesel 3.0L, 3.6L, and 4.2L engines from 1992–1995. Please check the "Engine & Model Compatibility" table and cross-reference your OEM part number (807166A3) to ensure a perfect match.
What are the signs of a failing exhaust water shutter?
Common symptoms include a rattling or clanking noise from the exhaust at idle, engine overheating at low speeds, or, in severe cases, water ingestion leading to hydrostatic lock. Regular inspection is recommended.
Is this sold as a single part or a pair?
This product is sold as a complete kit, which includes two butterfly-style shutter assemblies and four rubber mounting grommets, enough to service one V-engine exhaust Y-pipe.
What is the difference between OEM and this aftermarket part?
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.
How fast is shipping?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
What is your warranty and return policy?
This product is 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 for items that are unused and in their 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.
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