i have a 91 f150 with the inline six 4 spd and i have a nasty belt squeal the belt squeals when i start it and the goes away after i drive it for like ten min. the squeal also goes away/quiets alot when the clutch is pushed in i think it might be the belt but the belt looks brand new what do you guys think this could be? also when i start it up it sometimes will not squeal or go away right away

 

...it goes away when the clutch is pushed in.....

It's not a belt squeel it is a throw out bearing on the clutch fork going bad.

 

it may be a belt tensioner bearing or pulley bearing it may not be the throw out bearing, try using a stethoscope or piece of tubing to try and pin point the squeal.

 

Although a common problem is the tensioner bearing the noise shouldn't go away when the clutch is depressed if it is the tensioner.

An automotive stethoscope is an invaluable tool for a squeeling diagnosis.

 

tommorow i am going to take the belt off and start my truck if the belt is off and the squealing goes away i am going to spin all the pulleys and feel for resistance and listen for a very slight grinding if i take the belt off and the squealing is still there im going to assume its the throw out bearing or pilot bearing

 

Good approach. I agree in the idea that it probably isn't a belt or tensioner, since the clutch operation shouldn't affect either of those. I guess it is possible that if the clutch is dragging slightly the extra load on the engine could make the belt squeal until you push the clutch in, but that's a long shot.

 

i did not get a chance today to take the belt off but the squealing gets quieter when i push the clutch in its only completly went away when the clutch was pushed in once and usually if i let it idle for 2 min or so the squealing will stop but if i drive it it wont stop for like 10 15 min

 

thanks to everyone who tried to help found out it was the alternator took it to autozone and it failed their test and squeaked like hell in their machine put on new alternator and the squeak went away

 

anytime i knew it wasn't a throw out bearing.