If you decide to do this procedure I would suggest that you start with a cold engine in the morning that will reduce any risk of over heating since the t-stat has not opened and the engine coolant would have to start from scratch. Since it takes the engine about 5min to warm up this would give you plenty of time to find out if the alternator/serp belt is your problem...

 

Seeing as a cold engine takes a good 3 to 5 min to warm up and this process takes less then 1 min, overheating is the least of the issues.

Sheesh who would let their truck run for more then 3 min like this?

 

Hopefully he doesn't have to drive far for the noise to kick in, as it only happens when he's in gear, it appears, lol