I recently changed intake maifold and gaskets on my 2003 yukon 5.3. Engine has a chirp noise that appears to be coming from the bottom rear of the engine . [not a typical bearing knock] . The engine seems to run normal with no codes. The oil pressure gauge reads same as when new [ My shop said it was from the front y pipe. [possiby bad or damaged cat] . I changed pipe and still have chirp only after engine is warmed up. I changed belts and idlers . Water pump is original. Fan clutch appears ok . Anyone with similar problem ? thanx. I just found a video on you tube that shows someone else with my same problem. If i was a little more tech savy i could probably post the link . I found it by going to you tube and typing 2005 gmc yukon noise . video posted by desisanders. There are no comments on his problem either but i thought it might help to hear what I am hearing. I am lost on this and dont want to just start replacing parts . i appreciate any help on this thanx again. Been driving about 2k miles since last post . Chirp noise is the same. no worse no better. I have found several other posts in this forum and others with others having the same problem but no one seems to know what it is. The chirping is most noticeable at idle but you can hear it while driving. [only when engine is warmed up] . If anyone has had similar problem or has been able to fix it I would appreciate any help . thanks again .