Unknowingly ran my Jeep without any oil, and now it makes a knocking noise. We thought it was a lifter, so we replaced all those, and now it's still making the noise. Sometimes it seems to be coming from the top of the motor, other times at the bottom of it. I rarely drive it anymore, but while accelerating, it sometimes sounds like a loud ratteling noise. What could this be? Or should I just get a new engine alltogether?