Hi bumping this old thread as I think I am having the same problem, i have a high pitch whirring noise coming from the drivers side of the car where the belts are, first I thought it was the alternator but after reading abit more I think the noise might be from the belt being covered in oil, the noise started of just being occasionally but now it is all the time, it increases with the revs and also when I turn the steering wheel.
Took a couple of pics of the pipe above and as you can see the lower pipe under the alternator is cover in oil suggesting a slow leak,I think my fluid is also lower than it used to be but it is still at the "cold" mark in the reservoir. Surprise surprise my focus is a 1.6 also.
I have attached a couple of pictures of the pipe, best I could get, would someone be able to confirm this is the problem. Cheers