Loud Knocking

[SBMoss]

I have a 99' Mercury 150 Optimax that has been making a loud knocking sound in forward or reverse, sounds great in neutral. I was directed to change the lower unit and this did not fix the issue, I have also changed the hub for the prop. I have a check engine light on as well, but no warning horn. The noise sounds to be originating from the midsection. Any guidance at all would be greatly appreciated.

 

[Scott Danforth]

Time to pull it apart and find what is busted

 

[Faztbullet]

Knocks at idle rpm or all rpms??

 

[SBMoss]

Its heard more at idle. And seems to go away after the RPM's rise.

 

[Faztbullet]

Not unusual with a Opti with SS prop. It has non ratcheting lower unit and prop slows down when in gear idling and what you hear is clutch dog reengaging, also if torqueflow hub make sure it is tighten to 100ft lbs