Mine ticks at first too. Been doing that for almost 7 years.

Fact is our engines are noisy.... Because they are a Mercedes. If you want quiet and smooth get a Lexus. If you want noisy and clunky but last a million miles then get a Mercedes. Not trying to be rude... Just want you to know with confidence everything is ok. Some here had this problem to the extreme and had it fixed. But I don't think you have a problem.