I have a 2003 f250,4x4,v10. Every mourning after start up and after I start driving I hear a loud squeaking noise or a whinning noise, but I only hear it while the truck is in motion, and only for about 5 miles or so. Then it stops and I don't hear it until the next mourning. Any ideas

 

Driveshaft U-joint will do that. Is it speed sensitive, as it changes pitch or frequncy as you go faster? An alternator could be a source also.

 

A few things could do it. Any periferal engine component bearing, fan belt, tail housing bushing, U-joint, etc., etc.

 

Can you tell if it does it as RPMs increase?

 

Sqeeks are inherently illusive and usually go away at higher RPMs due to the loss of the harmonic effect. The parts do more sliding than rapidly grabing and letting go as the friction surface speed increases. Much like slowly scratching a blackboard (sorry I has to use that scenario) or probably the same is true with a violin but I never owned one.

 

Now with my U-Joints, I always figured the squeaking went away as RPMs increased simply because it became so high pitched that human ears could not hear it.

 

There could be some truth to that but a squeek is the rapid grabbing and letting go of 2 materials (chattering). There is a time factor in there and there is a point were the material can't grab and release fast enough. When you rub a champagne glass with a wet finger on top your finger is grabbing and letting go of the glass and every time it lets go the glass jerks (vibrates) and the sound is magnified by the bowl shape and the hard glass but if you rub it too fast the time factor sets in and your finger can't grab and release the glass fast enough so it resorts to merely sliding across the glass and the chattering (harmonic) noise disappears.