If you can turn the alternator pulley by hand and it slips on the pully the belt is probably loose. If you are losing coolant the water pump may be depositing the coolant on the belt causing a squeal until it warms up a bit. I'mnot familiar with your model and don't know if you have a belt tensioner that may be worn. It sound like a loose belt to me. If it is a V- belt they get glazed after years of use and harden a bit, and squeal.

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1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T