First off, I am new to the forum so hello everyone. I just purchased a 96 four door 4x4 blazer. I notice that when I first start it coming from the rear of the enginebay there is kind of a odd sound. It sounds like when the blower motor for the heater starts to go bad, kind of a growly whine. But I am positive its not the heater motor. But it only does it at start up, and only for about a minute or so then it goes away. And it sounds like its from the top of the engine towards the rear. Any ideas on what it could be? Any help will be greatly appreciated. Thank you.

 

Turn off all blower/heater settings on panel to know for sure.

 

It makes the same noise even with the heater shut completely off

 

This might be a long shot but mine was making a similair noise on top of the engine towards the rear and it turned out to be the large O-Ring surrounding the spider assembly. Might wanna check there.