Hey guys I'm new here but I do have a serious question. So I have a 2001 BMW 540i with 90,500 miles and recently we replaced the alternator, valve cover gaskets, timing chain gasket, and some other cosmetic stuff. However, whenever we start it there is a rattling noise in the front only during a cold start and it last for only a few seconds during the startup. I have looked it up and my theories are that it could be timing chain related(like timing chain guides) or possibly vanos issues. I doubt it would be vanos but honestly who knows. I'm leaning towards a timing chain issue but can anyone else shed a light on this?