Can someone help me determine the cause of this noise? I've got a 1995 Merc Alpha I w/135HP 4 cly I/O. <br /><br />While running today I suddenly hear a loud clicking/ratcheting sound from the lower unit. It varies with RPM, goes away in neutral. Same noise in reverse. I noticed that a few times I heard and felt what seemed like the boat shifting into gear on it's own while idling. The drive has plenty of gear oil in the res and I didn't hit anything. I didn't have any problems shifting when I moved the handle, just the noises.