Just purchased, 52K miles, locally MB dealer serviced by PO, all services completed on schedule, no open recalls. Noticable intermitent tick originating from upper drivers side of engine. Just had MB local dealer service, Mobil 1. SA had can of "MOA" formula (whatevere that is) added, said it may take a week if that might resolve it. Drove 60 highway miles next day, tick gone for the day. Later that evening after a 15 mile drive, ticking resumed as I was pulling into the garage.

MB newbie would greatly appreciate your advice on what it may be and next steps. Should I start a home loan process to pay for repair?