Howdy,
I own an 07 Edge, AWD, 35K mi, had the PTU replaced so that SHOULDN'T be an issue but all of a sudden I have a grinding noise at highway speeds. I replaced front and rear rotors and pads, (both worn but normal wear) and the wheel bearings don't seem to be a problem. If I can fix it myself I will but I'm at a loss here. Any suggestions?

 

Thats strange. I would check dust shields and retake the brakes apart and check it out.

 

and check the hubs!

 

Center bearing on the drive shaft..unless that's what the PTU is but I didn't know what that meant.

 

The PTU is, I believe, the AWD equivalent of a transfer case.

From what I've read, people have had to have the PTU seal replaced multiple times due to leaks. You'd be well-served to check yours as it could have leaked again draining the fluid... leading to the grinding noises.

 

You are NOT going to believe this. First, Thank you to all that responded, I haven't repiled as I just took a very long trip. Rust was the problem. Being in Upstate New York, that should have been easy to find! Pieces of rust where getting caught between the dust shield and the rotor on the pasenger side of the car, front and back. In fact, I had a squeal that drove me crazy and that was the dust shield on the rear passenger brake that just needed to be bent back with a screwdriver. Just goes to show, check the simple stuff first. Thanks again to all.