I've had water pumps on the brink of failure do as you describe; the bearings squealing until the seal-leak loses a little coolant that acts as a temporary lubricant. You might check around the water pump area for any signs of moisture and watch the coolant level closely until you find the source of your squeal.
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I've had water pumps on the brink of failure do as you describe; the bearings squealing until the seal-leak loses a little coolant that acts as a temporary lubricant. You might check around the water pump area for any signs of moisture and watch the coolant level closely until you find the source of your squeal.
It could be your alternator belt but I suggest you check all your belts you might need to tighten or replace them