2000 F150 4.6 SC auto
I am hearing a high pitch whining nosies coming from the rear of my truck any ideas? It happen around 35 to 45 mph but at highway speeds I don't hear it I put the truck in neutral and coast and still hear it. It just started about two weeks ago what should I check for?

Thanks

 

Could be bearings, differential, or a midget if you've run over one lately. I would lift the rear of the truck and spin the wheels by hand to determine where the sound is coming from.

 

Check your rear axle code to see if it is a LS differential. If so, it needs new fluid and friction modifier. If not, start with a fluid change and go from there. But check things out first, could be U joints if its more of a squeak.

 

See if your bearing seals are gone. When my bearings went on my Mustang there was a good layer of fluid where the drive shaft dissappeared into the tube.

 

In 2008 at 73,746 miles had Differential Service Pinion seal replace & Mobil 75/140 Sinthetic Oil truck has 97,845 miles on it now ?

 

Sounds like gear noise. If it was run low it could have scarred up the gears and causing them to whine. I just had the same problem a month or so when someone installed a rear axle seal backwards...