Vibration in my Merc 135HPV6 at about 3000PM

[Chris1956]

Ladies and gents, I have a vibration in the subject OB at about 3000 RPM. It sounds like reed valves vibrating, but that seems unlikely. The next guess is something on the motor vibrating in sympathy like the partially rusted exhaust pipe cover on my car. The vibration goes away at lower or higher throttle settings.

Any idea from the experts?

 

[cyclops222]

Sounds like a resonance frequency. Year of the engine ?
Are all parts of the engine installed ? Run with cover on it ?

 

[racerone]

edited