I've got a 2009 Nissan NSF8A3 that I use as a kicker motor on my walleye boat. I've probably got around 200 hrs. on the motor. I have slowly developed a vibration at certain throttle positions as the motor has aged. There has been a bit more noise that has showed up as well. I recently switched from the factory 3 blade to a 4 blade for higher thrust. This prop causes less vibration (expected with a 4 blade) but there is now a funny whine or whistle at certain throttle openings. The noise is coming from the cowling/engine area. I don't even know where to start looking for the noise. I've gone through and checked all nuts/bolts/etc. for tightness. The only thing I think may cause a bit of an issue is the motor mounts are pretty soft compared to what they were when new. All the riding around in the tilted position on rough water has fatigued the rubber a bit I think. This is about all I can come up with when it comes to the vibration, but the noise is a mystery. Any help here? Thanks!
