Originally Posted by chevymec

I repalced the lifters that did the same thing but the guy had been driving it like that for a good while. I put the lifters in it at 165k miles. Same noise again. Repalced the motor and when I tore the old one down I found the cam bearings toast. The lower parts were ok, sides had bronze showing the the upper part looked like black tar and was real rough to the touch.

2nd truck I know has 250k+ on it( 6.0) and does it after a about 3 or 4k miles on an oil change. He replaced the lifters in it tracking down and intermittent misfire.Change the oil and it stops.

Originally Posted by zeake

I have heard of this before. I would bet that his cam bearings are toast.