I am looking for information. I have a 2001 Yukon that has what I would call a 'knocking' noise. Actually, it is more of a loud ticking sound. When the car was new, it only did it on a cold start. Now, with 34,000 miles on it, the noise is constant. The dealer says there is nothing wrong, "they all do that." My guess is that if they all did that, it would be listed as a feature of some sort.......