Exhaust Noise

[duchess]

All,

Older 31' Open with 454s with excessive exhaust noise > 2500 RPM.

Noticed it quiets down while making a turn to port while @ cruise.

The exhaust exits the sides instead of the stern and wonder if maybe it's the s/board muffler.

Any thoughts would be appreciated.

[jclark003]

Reduced raw water flow can increase exhaust noise. Possible you have a restriction in the riser or heat exchanger. Or an impeller that isn’t moving enough water. Unfortunately it’s hard to tell how much water is moving visually.

[duchess]

Thank you for your response, however the Sherwood raw pumps are new, in 2022, and both engines run 150 degrees so I don't think that's it.