Drivetrain clunk

[Sailvi767]

My 2017 LSV has a clunk that occurs at about 1500 to 1800 RPM accelerating. It only occurs after the boat has been in reverse. It can be duplicated out of the water as well as in the water. Transmission was replaced per Indmar but no change. Anyone else have this issue?

[kerpluxal]

Had an issue in my 2010 clunking only when going into reverse... Figured out the problem when the boat would no longer go into gear (forward or reverse), stress cracks in the propshaft in the coupler... Figured it out when my propshaft was no longer in my coupler... 

[teamerickson]

Have you checked your prop nut? Maybe there’s a slight gap between the prop and nut? In forward the prop tries to go up the shaft. In reverse it tries to come off. Maybe the clunking is the prop slamming into the nut because of a gap. 

[Sailvi767]

I checked it and the dealer has checked it several times. It’s also repeatable with the boat on land.

[formulaben]

I would remove the prop and see if it duplicates.

[wdr]

A quick check, grab the prop and give it a quick twist in either direction. You will feel and see it on the prop or feel it on the flange/shaft coupler.

Edited June 6, 2018 by wdr

[Woodski]

@Sailvi767:  If the key on a tapered shaft is not fully in the groove it will not allow the prop or the coupler to seat properly.  I would loosen prop, check to verify key is fully down in slot and reassemble.  It is pretty easy to have the key slide up the shaft when installing a prop or the coupler.