Hello, my Audi (see signature) recently gives, I mean since it’s so cold, but doesn’t want to determine if it’s because it’s because of a really loud mechanical clacking of itself at the cold start for the first approx. 1-2 sec in the morning. After this 1-2 sec. it’s still to be heard but still not so loud. As soon as the engine is warm you can’t hear it anymore, only if you let it run and stand directly in front of the bonnet. nn it was changed only a few days ago together with the timing belt everything. On this occasion I communicated to the workshop master that the engine slightly clacks, he meant after the oil change it should be gone… But it is not. It is worse than ever. A friend said these are the valves / hydro plugs. Can this be? And what should be done to remove this noise? And is it harmful to the engine ? thx