I have a Yamaha 2006 F90 that just starting knocking on my last outing. I have never had an issue with the motor or leg previously nor have I ever hit anything. The prop looks fine. I found that the knocking only happens when in forward gear. It's fine in neutral and reverse. Knocking increases with RPM, you can actually feel the knock. I removed the leg oil drain screw last night and found probably an inch worth of metal shavings attached to the magnet which is much more than I've ever seen. It doesn't look good. I will be taking the boat into a dealer but am interested in your expert opinion as to what will need to be fixed. Lastly, what could have created this issue? I've never had issues with the leg previously and have the leg oil removed and refilled at the end of each season and have never noticed any water in the oil. I've also checked the leg oil level mid year and it looked fine. There have been some very fine shavings on the drain screen historically during year end maintenance but very little amounts.
