I am stuck. I've been tracking down this thumping/humming noise in the front end of my 99 protege 1.6 m/t. What has been replaced is; struts, wheel bearings, cv shafts, rotors, calipers and pads. I've finally tracked down the noise. It happens at all speeds from 3mph until infinity. Gets louder when turning right and/or braking. Its the intermediate shaft bearing, I found the dust sheilds have come off and left the bearing exposed. Sure id just buy the part from mazda and slap it in, one problem. The upper bolt on the back of the engine block spins free, but wont come out. Wont tighten either. Id cut the head off the bolt but I can't get to it... what do I do?!