Whining from rear of 2004 Ford Explorer

Whenever I am over 25-30 mph and accelerating, a whining noise comes from my rear. I thought it migh be tires, but notice that it only occurs when accelerating. If I put the SUV in 4 wheel drive, the noise lessens, so it does seem that the greater the torque on the rear wheels, the louder it is. Could this be a problem with the rear differential? How can I tell for sure

I’d at least pull the rear diff cover off and have a gander in there. What comes out with the old diff lube tells a lot of what’s going on inside the diff.


Thanks for responding…I did have the fluid changed a few weeks ago…seemed like it was a little better for a while but now its as lod as ever.

Ford Motor Company has a technical service bulletin out regarding this concern. They know they have a problem with these differentials, Changing the fluid might quiet it doen some but is not the fix. Chances are it will not cause a problem but will continue to be an agrevation until repaired properly. Check with your Ford Dealer even if it is out of warranty and see if he can help. There are monies set aside for situations like this; Ford calls them “after warranty adjustments”. Tis a fact!