(Chesapeake Bay, Va)
I have a 2004 yamaha f150 outboard. After running at about 3000 RPM for 20 minutes the engine started knocking real bad. After running a few test of my own it only happens when the boat is in gear and appears to be coming from the lower unit not the actual motor. It did not slow the boat down in any way or affect the handling. where I was in the Chesapeake Bay was about 45 Minutes back to my dock which didn't seem to matter to the engine but I was afraid of it falling apart right in the middle of the Bay as loud as it was. Any information on the cause and possible fix for this.