Ok first of all I know this is mostly a jk forum but I just bought my first jeep and a yj was what I could afford. I paid 1900 for it because it had a cracked head. I bought the new head and got it installed and drove it a little when it started to knock every now and then. I thought it might be a rod bearing so I took the pan off and replaced all the rod bearings and one of them had started to spin. But once I started it again it still knocked. So is it a bad main bearing or what? Please help!