My Blazer has a kind of squealing noise coming from the front of the engine, going up and down with the engine speed. It seems to be coming from one of the accessories, or perhaps the belt or the fan. Any ideas where I should start looking? Common problem this?

 

Its just a worn pulley or belt,its not a common problem,but not a rare problem either. Its just a problem that needs to be fixed. Only way you can really tell what it is is remove the belt,and spin the pulleys,if you feel/hear any grinding,sounds,worn bearings then replace the pulley. Buy a new belt for less then 25 bucks. I noticed these things like gaterback belts. Some other belts tend to squeak more then others.

 

Finally got around to replace the serpentine belt (used the gatorback like you recommended). The old belt was quite worn. The truck is quieter now, but that squealing sound is still there.

I tried spinning the pulleys (except the crank, obviously) by hand with the belt off, and could not hear much. I sort of suspect it is the fan. That - and the crank - is all that is left to squeal. Unless anyone has better ideas, I might go with an electric fan conversion.