e86 - weird start-up sound after Inspection 2 (video included)

[Latari]

Hello,

Got my e86 from Inspection 2 service few weeks ago (its been driven 110k km). Things worth mentioning replaced;
-spark plugs
-oil & filter
+as extra replaced the vanos solenoids (intake and exhaust) in order to get rid of emission light that has emerged every now and then.

However the car has developed a strange start-up sound after the service https://youtu.be/6Ut5eVUIxf0

Here are some characteristics of the sound;
-Never heard during cold start, only involved in start where engine warm
-Not heard during every warm-start either, heard only maybe 1/5 of starts
-As seen in video, eventually after 10-15 seconds, sound goes away itself
-Tone of sound not changing with revs
-No error codes
-Performance of car totally fine, on the road works normally.

In addition car has bit un-even idle during warm start, but that symptom has been there already for longer time even before this new worrying start-up sound. (unfortunately vanos solenoid replacement did not get rid of the problem either)

Sounding familiar? Any diagnosis? Much appreciated to hear experiences what could be the origin of sound! Last but not least, greetings from Finland, here´s some pics of my e86; http://maxmauku.1g.fi/kuvat/Automotive/BMW+Z4+Coupe/

 

[jan_tekin]

Hi, great photos

I think its possibly you belt tensioner

Part one shown here. Mine sometimes makes a similar noise and thats what I'm going to replace.

Guide can be found herer, access is little harder on ours so it will need to be done from underneath i think.