Rattle coming from the front of the motor

[UNOMYFLO]

Its not a squeeling noise it is a RATTLE/ VIBRATION noise. I have been restoring cars and working on them for 20 years and I have never heard a serp belt make a rattle noise. I am with F5Fstop I think it is the clutch fan mechanism...when the heat sensative bushing inside of the mounting area heats it expands and engages it, plus it must tighten up the juncture and eliminates the noise...I would like to have a definite on this though. I could pull the fan mech and check it just for the short start up period to see if it eliminates it.