Starboard engine “whirring”

[sixsandyfeet]

Couldn’t come up with a better way to describe it the sound.
2008 27PC, twin Merc 350’s. Buttoned her up for the season today . Fired up to idle to he pump out dock, and starboard engine didn’t sound quit right, making a “whirring” sound at idle and throughout the limited throttle range I was willing to test at the dock. She was not making this sound during the last outing 2 weeks ago.
Ran port and starboard together, starboard running about 15 degrees warmer, which stayed consistent to to pump out dock and back.
Thoughts? Sounds like bearings to me. Water pump? Impeller?

 

[afratki]

Definitely sounds like a bearing, could be any one of a number of things. If you don't have a mechanic's stethoscope, try using long screw drive (at least 2' long for safety) and probe the various components (water pump, belt idler and guide pulleys, alternator, etc.) with the engine running to find the source.

 

[La Cozzi Vita]

Is the sea cock that feeds water to that engine closed. Could be your impeller running dry. If open disregard.