I have been trying to figure out my girlfriends 2005 cobalt 2.2. It's making a loud noise, sounds like it is coming from the timing chain area. It starts up and runs fine doesnt make any noise for 5 minutes or so until it is warm. Once warmed up there is a loud noise at idle and if I give it gas when the rpms drop it will drop low or stall. I have changed the timing chain tensioner the balance shaft tensioner and looked at the guides which seemed fine. any suggestions would be greatly appreciated.
YouTube Link to the sound Cobalt engine sound https://m.youtube.com/watch?v=xDc1Y1fGd9Y
My car has 110000 miles.
My car has an automatic transmission.
Thank you for the link of the noise that you are hearing. The noise sounds like the timing chain is slapping the timing chain cover. Check the tensioner and make sure that it is tight. If the timing chain tensioner was replaced, then the guides could be worn causing the chain to slap on the housing or make the loud noise as the chain is rubbing on the tensioner. If the guides are in good shape then the timing chain is stretched and needs replaced. Even though the timing chain may seem tight when installed, but it will move around when under a load. As the engine speed gets to a higher rpm, the noise will go away as the engine is smoothing out. I recommend replacing the timing chain. If you need further assistance with your engine’s loud noise on or near the timing chain cover, then seek out a professional, such as one from Your Mechanic, to help you.