I hv an '04 with 5.4 3v. After it rains, I get this loud squealing/metal-on-metal sound in the engine compartment. It sounds like its coming from the ps pump, but I'm not for sure. It seems to be getting progressively worse ( taking longer to go away). I had to replace the thermostat today and after i finished, I hosed the engine off to remove what little bit of coolant that got on the engine. I drove to work and it just about drove me crazy. Any thoughts as to what it could be? Streering seems to be ok. I almost wish it would break/quit working so I can fix it.

 

have you looked at all the suspension make sure nothing broke loose, it might be the belt squealing

 

sounds like its the belt to me. is the tensioner working? take the belt off and spin all the pulleys by hand and see if you hear anything.

 

I know its not in the susp, because it does it when truck is not moving

 

Get a new belt.

 

possibly a locked up or locking up pulley if it has a metal griding sound, but probably just belt.

 

Definetly check idler and tension pullies as the roller bearings do go bad. They will Grind and lock up. I have had to replace them on several cars and trucks. I just had one that locked up on the idler pully and the gal drove it till the bolt froze on the inner race. I had to go to the boneyard to get a bolt for it as Ford dealer dose not have them and they don"t come with a new pulley. It is a special shouldered bolt and that is the only place I can find one. Best of LUCK!

 

had same issue when i had my explorer sport track, after a rain or when it was hummid out the idler pulley would sqeele like a pig, it was from the moisure in the air.