Hammer knocking noise when in gear over 3000 rpm
 

Helping a friend out with a 26ft cabin boat with 350 carb motor, Bravo3. At the dock on the trailer, if you rev the motor upto 5000, there is no extra noises. When you put it in gear at about 2500 it starts with kind of a exhaust leak noise but as you throttle up it starts sounding like a hammer hitting in the back, by the coupler & drive shaft. We pulled the drive and checked the gimbal and u-joints and found no problems. We can shift the drive and spin the drive shaft over by hand smoothly. Any ideas what to try? Coupler, flywheel.
I have a spare bravo1 off my 502 that we could use to try and isolate the problem. Will it fit on the 350, Bravo3 mount?

What year engine?

What do the props look like. Anything hitting

Not sure about year but guessing around 2006-2008. I forgot the mention he said he hit a sand bar with the prop earlier in the weekend, and an hour before the noise, it quit running while under power, but started right up. Guessing that is when the sound started, but he was idling then to go get gas so he wouldn't have had the noise.

2001 SeaRay Sundeck

The shafts are bent and something is hitting when under load.

To answer your question, Yes, a Bravo1 will bolt on when you remove the Bravo3.
Did this noise just start recently

Sorry i just read he hit a sandbar w/prop under power,
He had better remove it before it gets destroyed, something inside the drive is broken..

like 253 said,the b1 will bolt right on,i would put the b1 on and see if the noise goes away,if not something else is wrong.

If insured have him contact his agent. I've had a couple covered over the years. One was a sand bar and other was a dead head at over 80 mph and that one took the drive right clean off. That one I had my hands full trying to get the boat under control.