AndrewAZ

We had a topic about a strange thumping noise form the back of the car. Which some MB tech later responded it was the purge valve to some canister. Took the 07 E350 in and my SA heard it, got it back a few days later and it said reinforced and insulated purge valve to charcoal canister. Well the dam car still makes the same noise and now I think it happens more often or at least can be heard more often... Any advice or tips? It seems like every new MB car makes this noise even the darn little C class loaner cars.. Is this a quality issue or just a bad part? We have an 06 E350 and its silent as can be..