My 98 Expedition has developed a noise, metal on metal type, that is driving me crazy. It is not there constant, just once in awhile, and for a few seconds. At first I had a noise like the mud flap was rubbing the tire, but eliminated that. Thought it was a wheel bearing, that's not it. I figure that noise may be caused by the front calipers. Now I have what is best described as a sort of hestitation then the metal on metal noise. The front axle u-joints are solid and I can't find any "slop" in the front or rear differentials. The drive shafts seem tight. With 183,000 on her, it could be anything. Any comments or opinions would be appreciated.

 

Does it do it when hot and cold? I had a nasty tap tap tap that went away when warmed up. turned out to be an exhaust manifold leak.

If its a clunk or similar...check the ball joints...tie rod ends...ect.