Have had this problem for last 10k miles or so. Car is 01 V70 T5 at 113k miles.

When the car stops at a light/stop sign and get going again, there is what sounds like a higher pitch fog horn sound coming from the front end. It disappears quickly as you get going and never appear again while you are running. This occurs once in awhile with no particular patterns. In all occurrences, the car is going perfectly straight forward. Never have occurred on turns starting from stop.

PS fluid is flushed and full. Rebuild PS pump installed couple of thousand miles ago (The sound occurred before and after rebuild PS pump install)

Timing belt was done at 110k along with pulley and tensioner. Serpentine belt maybe 40k ago.

Alternator bearing? serpentine belt tensioner? Both of these are original. Anyone had this sound before?

 

I would remove the belt and spin the pulleys when the car is cold and see if they make any noise.