with the 4.0 ohv motors it the cracking of the flex plate a common occurrence? the reason im asking is that just recently my motor is making a really nasty metal on metal scraping noise. its not continuous nor does the tone change through the rpm. it only really does it at idle and low rpm. the noise is coming form the bell housing of my automatic trans. i know its not the torque converter because if it was i would know for sure.