Either it's the guide (idler) pulley, or the fan bearing is also a common high-mileage failure point. Just did mine earlier this year.

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Streetside: 1987 Mercedes 300E Petrol Blue/Green
2014 Ford Mustang Grabber Blue
1999 Ford Ranger Green

Dockside: 1968 Eltro 17
1985 Silverton 34C