Originally Posted by F104
it's simply a first level foam filter to prevent the larger pieces of sand, leaves, insects etc go into, and block the folds of the paper element. Open the airbox, most of the stuff you find lying on the bottom was kept out by the foam
Yeah, It's amazing how much of a vacuum cleaner our intakes are. I cleaned mine out 3k miles ago and opened it up last week to find it filled back up with leaves, bugs, dirt, salt, small pebbles, etc.
I know that the assembly is labelled "suction silencer/filter cartridge" but I do not believe that there is a resonator of any kind built into the assembly. Any idea what the "silencer" portion refers to if not the foam bit? It does seem odd that no petrol BMWs are equipped with this AFAIK, and i would imagine that if it were only for filtration purposes, the paired primary/secondary filtration configuration would be more common among the brand. The n/a vehicles seem to have an intake silencer built into the air duct (such as the 328, shown here: http://parts.bmwofsouthatlanta.com/s...roduct=8398318
), but the 335i has the suction silencer label and no visible resonator/silencer, so perhaps it is just referring to the box. Hmmm, perplexed...