Yamaha gearcase noise in idle forward

"I have new twin Yamaha 150 fo

"I have new twin Yamaha 150 four strokes with less than 40 hrs and both make a constant low clattering noise from the lower unit/gearcase when I run them in idle forward gear with flushing muffs and a garden hose. I don't hear any noise when the engines are in neutral. Both gearcase lubes have been inspected and changed, and the fluid was clean. My dealer says this is normal, that the props need the resistance of the water to take the up the gear slack. He may be right, because I don't hear this noise when the engines are run in idle forward in the water. So is this really normal, or am I getting bad info from the dealer and need to pursue this further?"

i would never put them in ger

i would never put them in ger on land

"I have the same problem with

"I have the same problem with my 2005 225 four strokes. The noise ocurres when I put it into forward or reverse but only at idle-600RPM. My dealer had no idea, tried different props new "thrust washers" etc. I have searched many web threads and have found a common anwser....The wave washer and 2 flat washer along with the plastic collar and metal cap that are on top of the impeller were not installed properly. Apparently you have to lift the drive shaft up while installing these parts(on top of the impleller). I guess the wave washer gives just enough cushion to the drive shaft stopping the "chattering" or "knocking"...hope this helps....steve"

you should not have to lift up

you should not have to lift up
the sound is the brass washer/bearing they used in the midsection