Possible oil pump problem. Upon cold start up, the engine "ticks" quite loudly.

Thanks for the advice. Mercedes dealers seem to be notorious for not exploring owner's issues.

That's the reason for my response, dont let them get by with excuses. Go over their heads if you have to! I know you may have to deal with this dealer in the future but right is right,, so make them FIX it!

They got the money ,they pay john boy good for those commercials.......

Well you guys are right. I left the car overnight at the Merc dealer, and they verbally told me they heard the engine ticking upon cold start up. But they said all the 6.3 litre motors do it and would only be abnormal if the sound doesn't stop when warmed up. So they won't do any more. They didn't put any of the conversation in the written record, so there won't be any recourse I guess if expensive repairs are needed after the warranty period is up. I plan on a written complaint to the dealer GM and Mercedes head office. Any other ideas?

Go over their heads, find out who the factory rep is, or you should be able to contact the main office and throw a fit. Those cars are advertised to be the best, and they need to stand behind them. Get their attention.

I will. I have already documented the issue and service advisor conversation in an email to the General Manager and Service Manager. Thx for the advice and diagnosis.