Hello,
I have a 2017 Lincoln MKX which I bought new and it has the AWD. I am quite sure the design is the same for both the Edge and the MKX. My car thus far made about 12 of these clunks so far and I have 20,000 miles on the car and just over a year of driving. When I back up about 5 to 10 feet, you sometimes get that clang. First time I noticed the clunk was at 15,000 miles.
I researched it and find that it is a also a common issue with many manufactures other than Ford for AWD vehicles. It appears that the noise is when the friction disks which engage and lock when you are going forward so more power is directed to the rear axle. When you back up, it unwinds the driveline and then it released locking device then the gears in the rear axle clang, only once. There seems to be no answer to the issue and is a common issue for many different manufactures.
I am planning to live with the issue since it is near impossible to duplicate at the dealership and seems like it is an inherent characteristic of AWD vehicles.
Are you still having the issue or did you get it resolved?
I am also in Iowa.
