My 2003 Expedition EB 4x4 is making strange noises from the front end. This is my second 03 so I am sure this isn't normal, I have a humming noise coming from the front end, it starts at about 43 mph and goes away just past 45mph. The noise is only there under power, if I lift off the gas it quits. I know it's not the tires as the were replaced last week and the noise didn't change. I had a friend that is a mechanic drive it and he suggested that it was the left front hub as you could also feel a slight vibration in the floor board and in the steering wheel. I've replaced both hubs and it does feel smoother but the humming noise is still there.
Now today on my way home from work I noticed a rattling noise, almost sounds like an exhaust heat shield rattling. It is around 30mph and quits passed that speed, after riding with my wife and listening out the windows it is clearly coming from the right front. If I turn on AWD or 4X4 the noise stops. I think it has to do with the vacuum controlled locking hubs, but I really have no idea how this system works or what tho look for.
Any help would be greatly appreciated - THANKS!!