I had my timing chains (and water pump) replaced on my 09 CTS about a month or so ago. Since day one after the work it rattled when it first starts. The noise (which sounds like a diesel) goes away a few seconds after it starts but it is pretty annoying and getting louder. The shop said to give it a few weeks and it should go away.....it never did. They also said it sounds like the tensioners are dry at start up but after the oil circulates it stops. Can anyone shed some light on what could be going on and how to fix it?? By the way the shop has agreed to fit it since it's still under warranty. Thanks for the help.