I've had this problem on both of my Foci. The tensioner had pretty much seized on both cars. I changed the tensioner and belt, and they've been great ever since.
Well I noticed now that it really only does it loud when the car is really cold. I started her up today and couldn't hear it, it seems like it only does it when I drive the car on a cold day before letting her warm up.
try turn on A/C, and see if the problem get worst. I have the same problem when start it will scream if the A/C is on it get alot worst I think my A/C is f..ked.
P.s I have new tensioner and new belt just past summer.
i replace my alternator - tensioner and it still whines - i am thou doing the big 3 on monday to stop the flickering
did you check your power steering fluid like I mentioned above...........
I had this problem, but mine was due to the udp, and slipping on the belt. Changed back to the stock udp and everything was fine. This was with the unorthodox racing udp.