I bought a 2008 280 Sundander....

[PPGWingman]

I bought a 2008 280 Sundander.  Recently while flushing the motors after a day on the water, I notice a squeal in both motors when the throttle was raised above idle.  The starboard was worse that the port, but both made the noise. Sounded to me like a pulley bearing, but I am not mechanically minded enough to be sure.  Any ideas on what it could be?  

[Thbouro]

May be loosen belt

[Jaay757]

If not belts. It could bec the noise from the throttle bodies. Not sure what u have fir motors, but there are2 small mufflers that go into the housing of the throttle bodies which are often not replaced. If they are missing when u throttle up it may sound like a squeal to some this is normal.. I have 8.1s and change these yearly.
Check the belts first.

[300_sunpancer]

Also, be careful when you throttle up. Mercruiser says to flush the engines no higher than 1300 RPM for up to 10 minutes

[Seabuz]

Check to ideler pulley on motor. I’ve had to change mine a couple of times. You can get them in a auto store for half the price.