Listen to this Strange (mystery) noise on morning start ups....

[vanossa 0]

Hi everyone. 93' 325i Coupe, Auto (360kms). Could anybody please identify what this noise may be? Sometimes it does not appear, but occasionally it's very clear. The sound is a knocking (rasping) every second or so ( it also may sound like a small/medium size dog barking next door) Car runs beautiful as usual and when this noise does occur it's gone after engine reaches normal operating temp. It only happens on the morning start ups. ps... sorry for the crap cellphone recording, but you can clearly hear it though headphones. Any and all suggestions or ideas welcome.

Thank you in advance.

http://youtu.be/ZLGc5MiWvVs