MA043HA

I searched this site and several others including YouTube for threads/posts and listened to scores of video recordings of engine noises but didn't find anything like this. A metallic whirring sound at cold startup lasting about 20 seconds then stopping consistently. Not heard on warm startup. Please listen to video with headphones. M273 engine. Thanks in advance for constructive advice.
http://www.filefactory.com/file/1n32...%20seconds.MOV

BenzNinja

iTrader: (4)

remove plug 6
cold start
if the noise is gone, then its your secondary air pump




MA043HA

Thanks BenzNinja! I'll check it out.

MA043HA

Still hearing noise with secondary air pump disconnected as suggested. After a couple of tries over several days I noticed the noise stops just after the body stops rising to its normal height which of course happens with airmatic.
New hypothesis - whatever pump or subsystem raises the car initially is making the noise when cold. To test this idea I started the car from cold and heard the noise for about 20 seconds as before noting again that it stopped just after the car had been raised to its normal height. I then pressed the button on the dash that raises the car higher than normal (very useful if your bumper should settle down on a granite curb or concrete parking marker). This immediately produced the noise again for about the amount of time it took to raise her further.
To me this is supportive evidence for the hypothesis that the part of the airmatic system which raises the car is making the noise when cold.

Any advice from this point?

BenzNinja

iTrader: (4)

i'll need your vin to check the system you have and give you description

MA043HA

WDDEJ86X79A020863

BenzNinja

iTrader: (4)

MA043HA

Thanks!

BenzNinja

iTrader: (4)

my pleasure