Quote:
Originally Posted by PhaseP
Sounds something plastic loose rattling in closed place. You have 330 which has an intake manifold with two DISA valves on it. One of them may have gotten broken and lose rattling inside. That is one possibility that comes to my mind. If you search for DISA on N52 you will find lots of information.
The other from your description "The noise seems to be coming from below the intake towards the windshield", the crank case ventilation valve that is tucked inside the folds of the intake manifold towards the windshield (firewall) side may have ruptured its membrane and flapping.
There is also possibility that some of the serpentine belt got thrashed to pieces and sucked into the engine through the front crankshaft seal. It is hard to believe this can happen there have been many reports on this, even pictures from inside engine with pieces of belt stuck at the oil pick up line filter. Maybe some piece got also made its way from the crank case into the crank case ventilation valve and flapping around there.
There is also possibility the belt swung and took out some breather line made it loose and rattling.
Good luck!
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Forgot to update what actually caused the noise. You were right, it was the broken rubber orange membrane from within the Crankcase Vent Valve (I took apart the valve and the membrane was ripped up). Once I replaced that, sound went away. I did have to replace the breather hose since it was brittle and got damaged during removal.
Crankcase Vent Valve broken membrane pictures:
https://drive.google.com/drive/folde...DQ?usp=sharing