Exhaust Water Shutter (Flapper) – Fits MerCruiser 2.5L, 3.0L, 3.7L Engines (Replaces 60930, 25-43809)

$26.99

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Exhaust Water Shutter (Flapper) – Fits MerCruiser 2.5L, 3.0L, 3.7L Engines (Replaces 60930, 25-43809) is backordered and will ship as soon as it is back in stock.

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If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This Exhaust Water Shutter (Flapper) – Fits MerCruiser 2.5L, 3.0L, 3.7L Engines (Replaces 60930, 25-43809) is an essential replacement part for MerCruiser stern drives. Specifically designed for 2.5L, 3.0L, and 3.7L inline 4-cylinder engines from various model years, it functions as a critical one-way valve in the exhaust system to prevent water from flowing back into the engine cylinders.

This part serves as a direct replacement for Mercury-MerCruiser part numbers 60930 and 25-43809, and aftermarket equivalent Sierra 18-2727.

Installs as a direct replacement for the original part.
Constructed from durable rubber to withstand the marine environment.
Includes the necessary grommets for a complete installation.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket brands.

Brand	Part Number
Mercury-MerCruiser	60930
Mercury-MerCruiser	25-43809
Sierra	18-2727

Engine & Model Compatibility

Confirm your engine model and year in the table below to ensure correct fitment.

This part is compatible with specific MerCruiser inline 4-cylinder engines. Verify your model is listed before purchasing.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.
MerCruiser	2.5L	120	4-Stroke	1987–1989	60930/25-43809
MerCruiser	3.0L	130-140	4-Stroke		60930/25-43809
MerCruiser	3.7L	165	4-Stroke	1988–1989	60930/25-43809
MerCruiser	470 (224 CID)		4-Stroke		60930/25-43809

Technical Specs

Product Type: Exhaust Water Shutter/Flapper
Installation: Direct replacement
Housing Material: Rubber
Dimensions: Length: 3.85" (97.8 mm), Width: 3.00" (76.2 mm), Height: 0.40" (10.2 mm)
Weight: 0.16 lb (0.07 kg)
Other Technical Attributes: Includes grommets for installation

What’s in the Box

1 x Exhaust Water Shutter with Grommets (60930/25-43809)

Installation Notes

Ensure the engine is off and cool, and disconnect the boat's battery for safety.
Locate the exhaust Y-pipe where the old water shutter is housed. You may need to remove exhaust hoses to gain access.
Carefully remove the old, worn shutter and its grommets. Take note of its orientation.
Thoroughly clean the seating area inside the Y-pipe to ensure a proper seal.
Install the new grommets into the designated holes in the Y-pipe housing.
Insert the new water shutter into the grommets, ensuring it is oriented correctly to swing open for exhaust flow and close to block water ingress.
Reassemble any removed exhaust components, re-connect the battery, and test the engine on the water while checking for leaks.

Troubleshooting & FAQ

How do I know if my exhaust flapper needs replacement?

Common signs of a failing exhaust flapper include a distinct rattling noise from the exhaust area at idle, water ingestion into the engine cylinders (hydrolock), or visible signs of cracking, brittleness, or physical damage on the rubber shutter itself during inspection.

What is the function of an exhaust water shutter?

It acts as a one-way valve, allowing hot exhaust gases to exit while preventing water from flowing back up the exhaust pipe and into the engine when the boat is decelerating or stationary in the water. This is crucial for preventing catastrophic engine damage.

Will this fit engine models not listed in the compatibility table?

We can only guarantee fitment for the specific engine models, years, and part numbers listed. If your model is not on the list, do not assume compatibility. Cross-reference your original part number to be certain.

How often should I inspect or replace the water shutter?

Lifespan depends on usage, storage, and water conditions (saltwater is more corrosive). It is best practice to inspect the shutter annually and replace it at the first sign of wear, hardening, or damage to prevent engine failure.

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.

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