99370A2 3-Inch Exhaust Water Shutter for MerCruiser V6 & V8
99370A2 3-Inch Exhaust Water Shutter for MerCruiser V6 & V8 is backordered and will ship as soon as it is back in stock.
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99370A2 3-Inch Exhaust Water Shutter for MerCruiser V6 & V8
99370A2 3-Inch Exhaust Water Shutter for MerCruiser V6 & V8 is backordered and will ship as soon as it is back in stock.
SERDAMARINE / MARINE EXHAUST PARTS
3-Inch (76 mm) Exhaust Flapper Water Shutter for 1982–1987 MerCruiser V6 & V8
This aftermarket 3-inch (76 mm) exhaust flapper water shutter replaces the exhaust water shutter in 1982–1987 MerCruiser V6 and V8 stern drive applications referencing OEM number 99370A2. It is the 3-inch nominal shutter version and is cataloged separately from 4-inch water shutters and clamp-equipped exhaust flapper valves.
Configuration & Specifications
| Nominal Shutter Size | 3 in. (76 mm) |
|---|---|
| Catalog Distinction | 3-inch water shutter version (distinct from separately cataloged 4-inch water shutters and clamp-equipped exhaust flapper valves) |
Engine Applications
Designed for 1982–1987 MerCruiser V6 and V8 applications equipped with a 3-inch (76 mm) exhaust water shutter. Match the original shutter size, engine year, and part reference rather than selecting by engine configuration or the term “flapper” alone.
- MerCruiser Stern / Out Drive V6 — Years: 1982–1987. Configuration: Requires 3-inch (76 mm) exhaust water shutter. Fits when specified
- MerCruiser Stern / Out Drive V8 — Years: 1982–1987. Configuration: Requires 3-inch (76 mm) exhaust water shutter. Fits when specified
Not Suitable For
Applications requiring the separately cataloged 4-inch water shutter version or clamp-equipped exhaust flapper valves.
Reference Numbers
These part numbers are provided for identification and cross-reference only; they do not by themselves guarantee interchangeability across different exhaust configurations or indicate manufacturer identity.
| Primary OEM References (3-Inch Version) | Mercury Marine / Mariner / Quicksilver: 99370A2, 99370A 2, 92852, 23-92852 |
|---|---|
| Aftermarket References (3-Inch Version) | Sierra Marine: 18-2733 Mallory Marine: 9-42801 GLM: 89160 RECMAR: REC99370A2 |
| Additional Associated Catalog Records | Mercury Mariner / MerCruiser Stern / Out Drive: 92802 Sierra: 18-2732, 9-42801 GLM: 89170 |
Supplied Parts
- Exhaust flapper water shutter
Service & Installation Notes
General service guidance only. Use the service manual for your exact engine and exhaust configuration.
- Allow the engine and exhaust components to cool completely, shut off the battery switch, and secure the ignition to prevent accidental starting before servicing the exhaust passage.
- Compare the replacement 3-inch (76 mm) water shutter against the removed assembly and the housing mounting points to verify matching nominal size and seating style.
- Inspect the surrounding exhaust passage for detached pieces of the previous shutter and verify that the new flapper moves freely without binding after installation.
- After reassembly, monitor the exhaust system during initial operation and stop the engine immediately for inspection if abnormal exhaust restriction or leakage occurs.
The Serdamarine Approach
Exhaust parts need a configuration match. Serdamarine focuses on marine exhaust manifolds and their related service parts. Application details, connection requirements and public reference numbers are presented together to support part selection.
Questions Before Replacement
How does this 3-inch water shutter differ from other MerCruiser exhaust flappers?
This part is the 3-inch (76 mm) exhaust water shutter corresponding to OEM reference 99370A2 for 1982–1987 MerCruiser V6 and V8 applications. It is cataloged separately from the 4-inch water shutter version and from clamp-equipped exhaust flapper valves.
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