Occasional noise when letting out clutch, '90 C4
 

Realizing that it's difficult to diagnose noise problems without hearing them...

I own a 1990 C4, and when I let out the clutch to start moving from a stop, I occasionally get what I can best describe as a "whaaaaa" sound. I want to say it sounds like metal plates rubbing, but I really have no idea.

The slower I let out the clutch, the less likely it does it, to the point where sometimes I'm getting some choking from the engine because if I let it out any faster, I'll get the sound. I also only get it when going from a stop. The sound seems to come and go, and I haven't been able to connect it with heat, although when it rained a lot one week it seemed to be doing it more, and my mechanic mentioned it might be a belt slipping due to moisture.

Anybody had a similar problem, or know of any possibilities?

You should be able to determine if it's a belt slipping, by blipping the throttle and listening for the origin of the sound. If the car is in Neutral and you hear the sound, it wouldn't be the clutch slipping. You might want to check the fan belt sensor. A bearing that is going, might produce that type of sound.