Cold Start and Clunk - Maybe secondary air pump in this case?

[trahsub]

I am familiar with the noise a lot (all?) of these E9x cars make when starting after the car has been sitting for a day or more.

My cousin's E90M3 has a loud clunk - which is not bearings - in which the severity of the 'clunk' increases the longer the car sits. I was at his place today and we took his car out after he had not started it for two weeks. The clunk was pretty significant! Much more so than what I hear from my car after it sits for a few days.

But I noticed his car started (not throaty off the bat)...then a few seconds later CLUNK...and then it got throaty in the cold start sequence. It did not jump into muscle car beast sound immediately.

So in this case, could the air pump be lazy and that is what we are hearing? I will have to have him record this as there was a definite sequence of events:

-1 second or so of normal (as in not throaty) sounding start
-CLUNK
-then cold start loud mode

Has anyone experienced this? Or is this just all the same as what other members hear?

[///M Power-Belgium]

Originally Posted by trahsub

I am familiar with the noise a lot (all?) of these E9x cars make when starting after the car has been sitting for a day or more.

My cousin's E90M3 has a loud clunk - which is not bearings - in which the severity of the 'clunk' increases the longer the car sits. I was at his place today and we took his car out after he had not started it for two weeks. The clunk was pretty significant! Much more so than what I hear from my car after it sits for a few days.

But I noticed his car started (not throaty off the bat)...then a few seconds later CLUNK...and then it got throaty in the cold start sequence. It did not jump into muscle car beast sound immediately.

So in this case, could the air pump be lazy and that is what we are hearing? I will have to have him record this as there was a definite sequence of events:

-1 second or so of normal (as in not throaty) sounding start
-CLUNK
-then cold start loud mode

Has anyone experienced this? Or is this just all the same as what other members hear?

Exactly !
Here everything about the cold start clunk noise => http://www.m3post.com/forums/showthr...ight=LIMITLESS

And the "Puma case" (paper) shows the ultimate fix for it , and "Vanos Gears" are not cheap...
Amen..