[scholzee]

My loud humming roaring noise is gone, it turned out to be a bad pass front hub / bearing assembly. My noise would not change while turning either direction or when in 4x4 or not. I finally put the Blazer up on 4 jackstands, wheels off the ground, front wheels removed. I let it idle in 4x4 so the front wheels were rotating. I used a mechanics stethoscope and could hear noise in the passenger side hub and none in the drivers side hub. you could feel a vibration / grinding in the control arm on the passenger side also. BE VERY CAREFUL WITH THE VEHICLE RUNNING ON JACKSTANDS AND HAVE A BUDDY WITH YOU. I have 4 very sturdy wide based Snap-On jackstands and had my wife present to shut the truck off if need be. Testing like this is probably best for the more experienced people or professionals. Hub was $ 125 at Autozone.