HELP - Cracking Noise in Lower Unit

[lemaysanch]

Greetings folks,

Engine is a Yamaha OX66 Saltwater Series II year 2000.
I've only had this boat for a couple of months, but yesterday while flushing the engine...I decided to turn the gear to backwards. Immediately I hear a semi-loud cracking sound coming from the lower unit...I felt the shock in my hand when turning the control back.

If I take the engine to Neutral, and go reverse again then there is no noise the second time around. However, if I decide to go forward I hear the noise again (crack crack crack)...If I decide to go forward again a second time, no noise either.

I understand that when prop is running one way I need to give it time to reverse....but still leaving 2 minutes in between shifting forward and backward I hear the noise....is this normal?

 

[BOAT DOCTOR]

Re: HELP - Cracking Noise in Lower Unit

check your prop nut make sure it is tight if it is tight drain your lower unit oil look for metal or a grayish looking oil if they have metal you have a problem. also when you shift dont easy into shift it hope this helps

 

[rodbolt]

Re: HELP - Cracking Noise in Lower Unit

gearcase noise in gear on a 3.1L out of the water is rather normal.
however I really cant see the need to shift gears while out of the water except maybe after servicing.
and yes its normal for the prop to rotate even when in nuetral out of the water.