Alright i been looking for this for quite some time now and there are many possible answers but still not sure. Ok, so this is my problem, my 96 chevy blazer has a weird grinding noise coming from the front no particular side sometimes it seems its coming from the left but sometimes from the right. i have replaced all the front suspension components, such as ball joints arms, bearings and all that good stuff. First, i replaced the brake and rotors but grinding still there. second, i replaced both bearings at the same time and the grinding still there. I have checked and double checked the rotors for any unusual scratches and its all fine. I also read it might be the differential, how can i check for that? the sound is there when i have in in 2 and in 4. Any suggestions

 

Are you positive the sound is coming from the front? It could possibly be a rear axle bearing too. External noises are really hard to pin down. Its also possible that its a CV, or even the front diff. I was in a similar boat, where I had a grinding noise that continued after replacing most of the front end stuff including brakes, hub bearings, and CV's. It didn't go away until I replaced my front diff when I changed both front and rear to get lower gears.

 

to check the diff, get a clean bucket and drop the oil out of it and inspect the oil for shiney metal shavings. if you have a lot than most likely the bearings in the diff are shot. very common on gm trucks. i rebuilt a bunch of them when i was at the dealer. not fun.