Thread: Vibration noise
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      01-28-2013, 04:01 AM   #17
hobo mofo
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Drives: 2007 325i e90
Join Date: Apr 2012
Location: London

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Quote:
Originally Posted by poggy View Post
If its a metallic rattle that could be under the bonnet, it could be the overrunning alternator pulley - it has a clutch in it that allows freewheeling in one direction to take up sudden changes in engine speed. When the clutch stops working, the changes in engine speed cause the belt to rattle the tensioner. Was doubtful when mine was diagnosed but a new one totally cured it. Most noticeable when pulling away and engine is cold.
This is intresting because mine does have abit of a rattle but i thought it was just down to the cold weather.
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