[O Haiii]

My 2nd car has a 3.8 liter V6 engine with about 60k miles. It's doing something pretty bizarre. When i start the car when it's warm, there is some kind of a grinding noise in the engine bay for about 5 seconds and then goes away completely. Completely cold start the noise isn't there. Hot start (aka shutting off after a drive then restarting right away) exhibits zero noise as well. It's after about an hour of cooling down after a drive (so the engine is neither hot nor cold) the noise presents itself. The noise seems to be coming from the engine itself and not any other components although i cannot confirm that with certainty. Other than that the engine runs perfectly fine and burns zero oil. Any idea what this can be? Thanks in advance.