f250 rattling noise from lower unit

[robaloroger]

I just bought this motor. It is a 2006 f250tur. I just got done rigging the motor on my boat and fired it up on the hose. When the motor is in gear a few hundred rpms above idle I can hear a rattling noise coming from the lower unit. When I accelerate I do not hear the noise or maybe it is getting drowned out by the sound of the motor. It does not do it in neutral. i took the prop off and the noise stopped. I put a different prop on and the noise is back. I shut the motor off and wiggled the prop back and forth and I think I hear the noise. Any ideas? The motor has new gears in the lower. I am wondering if something went wrong on the reassemble.

[renegade15]

Hmm, it could have been shimmed incorrectly, but is there any slop between the prop and prop shaft splines? I know mine has a little and the prop will make a light rattleing noise when free spinning out of the water. I'd see if you can swing by a mechanic just to hear the noise, I would think someone would be willing to take a listen free of charge?

[boatguy823]

normal prop rattle on the larger yammies.....goes away at about a 100 rpm doesn't it.......for about 900 bucks you ca make it go away with the new sds system from yamaha. It entails a new prop with a newly designed hub and thrust washer. Pretty pricey to make a little noise go away.