I've got an 06 Sebring that was rattling at startup. I put in new chains, tensioners, and a water pump, at 89K kms. It was good for about a month, then this knock started. When I use the stethoscope, you can hear it but it is really quiet, and I cant get it's location. An inspection of the cams, rockers and everything , looks good. I was really hoping I'd screwed up and I'd be able to find something, where the sound seems to come from. Chain runs quiet, and the car runs smooth. Has anyone heard this before?