So this is my sisters cobalt. She had the engine replaced due to a broken rod last summer.. This engine has around 90k miles on it. I just changed oil a week and a half ago and it started making this noise about 5 days later. I don't think it's related to the oil change though. Popped the valve cover off and took the top chain guide off.. Timing chain seems firm and tight not much slack at all. Cam, rockers, springs, etc.. Seem all ok. Could it be lifters? Anything these engines are common for? Would a tensioner make this noise?
Here's a video of it.
https://m.youtube.com/watch?v=6jFwuszjZjc&feature=youtu.be
What oil did you use? Does it go away after warming up?
"In Oldskool we trust"
Formula shell 5-30... No stays the same. I'm thinking has lifter or valve. Just replaced the tensioner, while I was in there I found a rocker that was easy to move on the opposite side of the roller tip, guessing Ill have to have the head pulled
Sounds like you're on the right track. I will say, though, that the rockers are often easy to wiggle around.
"In Oldskool we trust"
Wiggle yes, but I could pish the back side opposite of the roller, up and down with a screwdriver effortlessly
