I own a 1996 Jeep Grand Cherokee with a 4.0L full time 4 wheel drive with 108,000 miles on it. The recent problem I am experiencing is that when I'm driving the car will sporadically start making a metal on metal grinding noise that seems to be coming from the front end. It happens only once and a while and lasts for about 10 - 15 seconds. As soon as any brake pressure is applied the sound goes away. I have also noticed that If I make a sharp left turn I will sometimes get a clicking noise like the Half Shaft is going out, but again this only happens once in a while. Going from forward to reverse seems to make the grinding happen more frequently. In the past year I have already changed the following
-Both Half Shafts
-All Brake pads and Rotors
-A Used Transfer case was installed with a used front drive shaft (This was done 9 Months ago) I am thinking that it could be my Front wheel bearings, but I do not know why the noise is so inconsistent if it is a wheel bearing. There is only a slight chance I believe ball joints are at fault because of the noise (there is no clunking). I have also been told it could be the U Joint, but I have already had one go out on my Jeep, and it is not making this noise nor does there seem to be play in the joint. I have checked the dust guards and the are not making contact with the rotors. There is something wrong and I cannot figure it out, any help would be appreciated. I have no problem changing the wheel bearings, but at $140 a pop, I don't want to change them if they are still good. Could it also be a differential problem, my thoughts are that if it was it would consistently make the noise, which is not my case. Please Help.