I have a 2003 F150 4.2L v6. Standing in front of the truck looking at the engine, what is the pulley called on the very lower left side. I have a squealing noise coming from the engine somewhere. I changed the belt and the idler pulley and that didn't help. What else could it be???

 

Use a long screwdriver and touch It against a non moving part of the pulley then put the other end of the screwdriver against your ear. Or go to harbor freight and get a stethoscope.

 

Tensioner maybe?

 

You don't have a picture diagram on the shroud under your hood? It tells what is what.

 

Yes there is a diagram but it doesn't name the pulleys.

 

Well I know mine does!

 

I know on my5.4 its the a/c compresser pulley. Probably needs replaced, I had mine done at 117k