What is that noise? (water pump)

[Charlie Foxtrot]

My guess is that most readers will already be familiar with the water pump on the 4.0L 6 cylinder engine. It's one of the most basic pumps out there, and replacement is very straightforward. How to R&R is not the point of this short posting. I had an intermittent squawking, scraping noise that sounded like a failed bearing on the front of the engine, not in it. Kind of like an idler pulley or maybe a water pump. Took the belt off, no noise. Rotated/spun every pulley, no noise. Replaced the belt. Noise re-appears. This was driving me crazy. Replaced both idlers, still had the noise. Used the stethoscope, and it sure seemed like it was coming from the water pump area, but the pump was not leaking. In over 40 years of turning a wrench, I've never seen a failed water pump bearing with out a leak, but what the heck. Pumps are cheap, I had some antifreeze on the shelf, & I'd tried everything else. Pulled the pump. This is what I found. Even though the pump rotated freely w/o noise when I spun it by hand, the minute the tension of the belt was on it, the impeller was touching the cylinder wall. (see photos)