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Probably something wrong with the accessory drive.
With another car I started the cold engine and heard a noise. I confirmed the noise was coming from the accessory drive by removing the belt and starting the engine and letting it run just long enough to confirm the noise was gone.
A check of all the accessory drives for play found the water pump with some. Not much but the other drives: power steering, A/C compressor, alternator; and the idler roller or tension roller bearings; clearly none of these had any play.
Also, the inner edge of the serpentine belt was sharp. And the belt was new. Looked at the old belt and both edges were "dull". The bearing play in the water pump was causing the belt to rub on the side of the pulley. Serpentine belts should not make any contact with the pulley sides.
Then with another car heard a dry bearing sound. Long story short turned out to be a bad idler roller bearing. I had all idler rollers and the tensioner replaced.
Years/thousands of miles later heard a faint intermittent chirp upon engine start. Turned out to be another bad idler roller bearing.
With that much noise if the noise is coming from some accessory drive component I think you'd be able to ID the component with a check for play, signs of wear/rubbing.
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