Hello Everyone, newbie to the Forum having recently aquired a 2005 ML 320 Cdi and hoping for some advice.

Sorting out various oil leaks on the engine, I replaced the charge air muffler (between turbo and intercooler) and now have a loud rumbling noise on decelaration. The noise can be clearly heard even when the car is stationary by just applying some revs and falling back to idle.
According to the MB dealer who supplied the new muffler, this noise is "normal", but the old unit that was replaced didn,t make any noticable noise?

Any advice/comments would be useful

Thanks