Mercruiser Engine knocks in neutral, goes away in gear

[greg82255]

Hi All,

I have a '86 Mercruiser 260 setup with a custom 383 I built a few years back. The past 2 times I have taken the boat out, after a few hours of cruising, I have noticed that the engine is making a knocking sound in neutral. It only happens after a few hours of cruising and in neutral. In gear, the sound goes away. I haven't been out to the boat this week so I don't have a video, but any guesses what might be going on? Thanks in advance.

 

[Rick Stephens]

Ujoints maybe.

 

[greg82255]

Whole outdrive/u-joint setup is brand new. Blew up the gears last year by forgetting to put gear lube inside, so I replaced the whole thing.

 

[Scott Danforth]

maybe the issue is in your signature line...... LOL

can you use a stethoscope to determine where the noise is coming from? could be coupler coming loose, u-joints, or something else.