Volvo D2 55hp Saildrive

[peterbotto]

The above engine in my Bavaria 42 Cruiser has done around 100hrs and between 1000 and 1500 rpm I get a high pitch resonating noise,from time to time, a bit like a loose fan belt but I have checked the belt and it seems tight enough. Once past 1500rpm all is normal.
This can happen when both increasing and decreasing the engine revs. Any ideas?

 

[branko]

I had this situation twice and at the end I found out that Zinc anode on saildrive, in front of the propeller, was unscrewed ( 2 screws) and make noise on some rev. You can solve this problem only when boat is outside the water.