Ok, so I bought a 2004 aveo hatch with 77k miles for cheap because the girls mechanic told her the camshafts were super worn and needed to be replaced because of "Korean metals". There is the usual valve chatter, but on and off there is this louder noise that sounds almost like a bolt bouncing around. I pulled the valve cover and the camshafts are perfect. I poured 10-40 all over the lobes and lifters closed it up and started it and the normal valve chatter was gone but the bouncing bolt noise was still there. It is gone sometimes, it is louder sometimes. Sometimes it's very slight. Checked the plugs, they're fine. The timing belt was done at 68k.

Did a compression test and it's 200 on all 4 cylinders, perfect. The noise seems to be coming from the intake side of the left most cylinder when looking at the car from the front. Any ideas? It runs fine, doesn't overheat, doesn't have any misfire or surging idle.....but it is so loud sometimes. I can't figure out what the heck it is. Do the valve guides come loose on these things or something? Looking at trying 5w-40 to see if that quiets it down. Any help is appreciated.