I have a 2014 Silverado LTZ (very high milage - 219,000) Runs great and still has some power left under the hood. For the most part, it is in great shape. It have a strange noise when acceleration or getting up to about 3 or 4 thousand RPM. It only does it under load, so it is hard to find where the noise is coming from. In the attached video, it takes place at 12-18s and then again at 40-46s. It is hard to hear because of the wind noise, but I can't figure out how to isolate the noise any better. If anyone has any ideas, I would sure appreciate the input. The water pump was just replaced, and so was the alternator, along with the tensioner pulley. I admit my limited knowledge under the hood, but I am willing to learn and fix it, if I can.
https://youtu.be/PctCm6Ai09Y