Ford Customer Service called again today to give me an update. They are still no closer to determining the source of the car's hum. She briefly explained how they use chassis ears to diagnose the source of a hum and that they are continuing to look for the source. She'll get back to me on Wednesday.
The service manager from the service dealer also gave me a call today. That was fairly disheartening. He told me that they have used the chassis ears on every part they can think of to find the hum and can't find where it's coming from. The first thing they tried was the wheel bearings, then the intermediate assembly, intermediate bearings, top bottom and sides of the transmission, motor and transmission mounts, and even the car's floorboards (because you can feel the hum through the floorboards as well as hear it). He said that they continue to call the Ford hotline for help, and that he has so far described my issue to no less than 4 different technicians. As we can all imagine, it's very hard to describe a humming noise over a telephone.
He said that the next course of action will involve a Ford Field Service Tech stopping by to drive the car and hear the hum for himself. This is why he drove my car and compared it to another car on the lot that does not hum. This is what the Field Service Tech will have to do to see that there is actually a strange issue with my car. He may or may not get the Field Service guy to stop by tomorrow depending on the Field guy's schedule, and he'll call me back tomorrow about it (Tuesday). He estimates that they would need the car in the shop a minimum of 3 days should that tech be able to stop by and help diagnose the problem....
This sucks. The question I can't help but ask is, what happens if they can't find the source? I love my car to death but I can't live with a car that sings a crappy tune to me when I drive between 45 and 60 mph
Still have my fingers crossed, I just want it fixed!