I am trying to diagnose a noise that is tied to engine speed, not vehicle speed.

I pulled the belt off to see if that would affect the noise. It idled really high and sounded really bad, so I turned it off after a couple seconds. Using a stethoscope I have not been able to source the noise at a pulley or alternator or condensor. Atleast nothing obvious. The tensioner and idler pulleys are new or good, the water pump and fan have zero play in them.

The noise is like a plastic scraping.

Question is assuming it never gets hot, is it okay to run it with out a belt for a minute or so?

Other suggestions?

 

Yes..,, for a minute or 2

 

Plastic Scraping?

Fan blades hitting shroud, but that would be obvious.

 

If you have recently changed any hose clamps on the top near the fan look for the extra hitting the fan. after I replaced my cooling system I had the plastic tip on the clamp hitting the fan. made a god awful noise. but like previous poster stated "that would be obvious"