Hi, I have a sweet 16 fitted with a 4.3 Mercruiser, I had been noticing an odd vibration at slow speeds and the odd clonk and some times a ringing sound when I snap the throttle open, so today I had a poke about in the engine compartment, well.....I found the harmonic damper had come apart, no trace of any rubber,and the two face's that the rubber should be bonded to are very nicely polished, so I imagine it been broken for sometime, I have only owned the boat for a year, and I know it had not been used for about 5 years before I bought it.
Its not to much of a problem, I just wondered if these things are prone to braking up or is it "just one of those things", I'm in the U.K.