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      02-19-2013, 10:11 AM   #3
New Member

Drives: 2009 E90 335i
Join Date: Jun 2012
Location: Ohio

iTrader: (0)

I had a hammering sound in my old 330i that seemed to be coming from someplace behind the dashboard, and only at idle. Checked all the heat shields, they were secure. Dealership had no idea, a local indy thought something might be caught in the header or cat. It went on for about a year, but then last spring I was doing a fluid and filter change and found a loose washer bouncing around in the engine air filter housing. Once that was gone, so was the noise.