E92 M3 - Metallic clunk / grind on cold start (With 3 Videos + Image of Noise)

[bradleyland]

Originally Posted by SenorFunkyPants

Hmmm except it doesn't account for why the engine starts quiet waits a second or two then makes the noise.
It "could" be a function of oil pressure, as it could equally be a function of engine temperature.

Maybe, except for no. The engine temperature does not climb that quickly (seconds). It is not irregular at all for lifter knock to occur a few seconds after startup. The hydraulic lifters are in an expanded state when the car is turned off, The valve action at startup is what causes them to momentarily collapse.

[SenorFunkyPants]

Originally Posted by bradleyland

It is not irregular at all for lifter knock to occur a few seconds after startup. The hydraulic lifters are in an expanded state when the car is turned off, The valve action at startup is what causes them to momentarily collapse.

You think the noise is from the lifters?

[NashvegasR]

Mine does it also (2009).

Sometimes it's very loud, sometimes not at all, sometimes just a faint noise. Always about .5-1 sec after startup and sounds exactly like the clips posted here.

This wknd I test drove a 2011 M3 convertible at Nally BMW in Atlanta. Same noise. I asked a tech about it as my car was in the service area getting a new wheel and oil change. He said "it's m-distinctive clatter on startup"...nothing to worry about.

My experience w/ BMW dealers is that they will happily endlessly diagnose any noise or rattle -- and charge me for it. He was pretty clear that there is no fix and almost all M3's do it.

[bradleyland]

The only relationship I can think of between the brake pedal and this noise would be the vacuum system. It takes a seconds or two for vacuum to build up when you start the car. This vacuum is sometimes used to actuate other systems on a car, but these days, it's more common to use a solenoid these days, because electronics are so cheap. When you press the brake pedal, you actuate the brake booster, which is basically a giant cylinder that gets drained of pressure by the vacuum system. This creates a large draw on the vacuum system, which will cause it to take even longer to build up a vacuum.

If the brake pedal actually does anything, my guess is that it prevents the immediate build-up of vacuum, which delays the actuation of some other system.

[iansanderson]

Originally Posted by L4ces

I am certain it is the same. In the video I am posting, the sound is more faint because the phone is near the engine bay. Had I recorded from within the cabin the noise in question would be more distinct. It goes without saying that one has to listen carefully to pick it up.

My car sounds identical to this video: clatter then clunk noise. Just heard it again tonight after leaving it sit for about 4 hours. I am still under CPO. I'm 50/50 if my dealer will say it's "normal" or actually try and diagnose. It's definitely one or more the vanos unit(s).

I have a 2008 6MT.

[BMWNTHZST]

I heard this noise for the first time ever just the other day

In my case it happened just after I pushed the start button, the engine was only in it's first rotation of turning over. It was extremely noticable. My wife (who never hears any odd sounds) even said what was that!

At this point I do not see any reason to take it to the dealer. I'm still under warranty and it only happened once.

Subscribed for any updates on the cause....

[Cyclone Chris]

I've heard the same noise on my 2013 with 5K miles. Typically is only happens after the car had been sitting in the garage for a few days.

[///M Power-Belgium]

Originally Posted by Cyclone Chris

I've heard the same noise on my 2013 with 5K miles. Typically is only happens after the car had been sitting in the garage for a few days.

I see your car has "DCT", so you can try "the brake procedure" .

[bradleyland]

Originally Posted by SenorFunkyPants

You think the noise is from the lifters?

The noise I heard in some of the videos sounds a lot like lifters. It's hard to hear over video recording, but I've heard what I think is lifter knock in my car on a couple of occasions too.

[anom3]

welp, some progress.

i had a chance to have the gf start the car while i had my head under the hood.

100% without a doubt, coming from the drivers side vanos area. i actually had my head on the other side watching the belt / ac compressor and the noise was so present on the other side that i turned my head right as soon as i heard it.

worth noting the one time i did this with the intake manifold off i thought it was coming from drivers side as well, but i was quite a bit 'deeper' into the engine bay and paying much more focus on the valve covers rather then the vanos.

i think this is the way to go for the time being. i'm going to do this a few more times over the next couple of days focusing more and more on the drivers side seeing if i can pinpoint if its coming from the vanos or under the valve cover.

last but not least, when i said 100% without a doubt... i mean it. im not deaf or dumb... the noise distinctly came from the drivers side vanos. my face was directly over the passenger side vanos as like i said, was watching the belt as i wanted to see if there is a some sort of delay between when the motor ignites and the belt starts spinning. passanger side vanos, nothing, drivers side vanos, grind!

stay tuned

[s85e90]

The Saga continues. I'll say it again, save your money, but it's yours not mine. On another note I'm up to 55k with my second m3 making this clunk w/ ZERO issues. Normal M clunking for sure.

But I am curious to see if you'll ever get it silent. @M3po your's still quiet?

[///M Power-Belgium]

Originally Posted by s85e90

The Saga continues. I'll say it again, save your money, but it's yours not mine. On another note I'm up to 55k with my second m3 making this clunk w/ ZERO issues. Normal M clunking for sure.

But I am curious to see if you'll ever get it silent. @M3po your's still quiet?

Like I was saying several times it's the Vanos gears , and he (anom3) can get it quiet by replacing them,and it's needless to say it's....$$$$ !
And I need to repait my question...
What I realy don't get is the fact that pulling the problem out ( the Vanos gears) and replace them with the same problem ( the new Vanos gears ) and so with exactly the same Vanos gears will make it quiet ?!?!
I realy wanted to hear an explanation for this , but i'm sure it never will !
BTW....I'm making mine quiet by using the brake procedure (DCT) and that's the second mystery of the clunk noise

[nusevad]

Originally Posted by ///M Power-Belgium

I'm making mine quiet by using the brake procedure (DCT) and that's the second mystery of the clunk noise

what is the DCT brake procedure?

I have this clunk as well, especially if car sits for awhile.

Do you guys think that this leads to vanos gear wear which will lead to a expensive repair soon?

[///M Power-Belgium]

Originally Posted by FifthStreetz

what is the DCT brake procedure?

I have this clunk as well, especially if car sits for awhile.

Do you guys think that this leads to vanos gear wear which will lead to a expensive repair soon?

The DCT brake procedure is.... > # 4 on this page > http://www.m3post.com/forums/showthr...3#post16319163
Please post the result !
About expensive repair...saw on here owners with 60-70K miles on it with the clunk noise,so who knows ?

[anom3]

just thought i would chime in...

since i now understand a lot more clearly how vanos works and its interaction with starts / cold starts..

i decided to email bpmsport and get another tune, with cold start ENABLED.

flashed it today, noise still there... forgot how loud this car is @ cold start with the cold start enabled...

regardless, this issue is not caused by the cold start delete from bpmtune.

[///M Power-Belgium]

Originally Posted by anom3

just thought i would chime in...

since i now understand a lot more clearly how vanos works and its interaction with starts / cold starts..

i decided to email bpmsport and get another tune, with cold start ENABLED.

flashed it today, noise still there... forgot how loud this car is @ cold start with the cold start enabled...

regardless, this issue is not caused by the cold start delete from bpmtune.

Exactly the same case here , when Mike (BPM) removed my cold start cycle clunk noise was still there,now I realy missed the sound of the cold start cycle,so Mike turned the cold start back on,same thing the clunk noise was still there !
So "with" or "without" cold start cycle the clunk noise lives on !
I'm keeping it for the moment with the "DCT brake procedure" it works 100% for me, just flawless !

[USCTROJANSFIGHTON]

Drop off my car Monday.
They are still trying to finding the cause of the metallic clunk on start up. M3PO mention the VANOS. I showed them a copy.
Their technician are communicating with BMWNA to open a PUMA case.
Still under original warranty......so no worries on my end.
They think it is something other than VANOS...


I'll keep everyone updated.

[USCTROJANSFIGHTON]

Originally Posted by ///M Power-Belgium

Exactly the same case here , when Mike (BPM) removed my cold start cycle clunk noise was still there,now I realy missed the sound of the cold start cycle,so Mike turned the cold start back on,same thing the clunk noise was still there !
So "with" or "without" cold start cycle the clunk noise lives on !
I'm keeping it for the moment with the "DCT brake procedure" it works 100% for me, just flawless !

You shouldnt have to do the DCT brake procedure. It's not normal..
Hopefully I will have an answer in a couple of days...from the dealership

[///M Power-Belgium]

Originally Posted by usctrojansdent

You shouldnt have to do the DCT brake procedure. It's not normal..
Hopefully I will have an answer in a couple of days...from the dealership

Agreed it's not normal , we all know that .
The only solution that we saw on here was replacing the Vanos-Gears but it's very expensive !
Please keep us posted with updates from your dealership.....

[anom3]

please notify as to what they come up with.

i am still getting this noise.

although its quite a bit better now.

i switched to 0w40 for a while and ran a bottle of ceratec thru the oil for about 5000K KM. it seams to have helped quite a bit.

but i would still like to get this resolved 'properly'.

thanks!

Originally Posted by usctrojansdent

Drop off my car Monday.
They are still trying to finding the cause of the metallic clunk on start up. M3PO mention the VANOS. I showed them a copy.
Their technician are communicating with BMWNA to open a PUMA case.
Still under original warranty......so no worries on my end.
They think it is something other than VANOS...


I'll keep everyone updated.

[lockeed]

Mine doesn't do that, and it's not a normal sound. No doubt you should be able to pinpoint the source.

As stupid as it may sound, did you checked the engine and exhaust mounts? Mine produced a similar sound from the back when the weld on my muffler support brace broke off...

[///M Power-Belgium]

Originally Posted by lockeed

Mine doesn't do that, and it's not a normal sound. No doubt you should be able to pinpoint the source.

As stupid as it may sound, did you checked the engine and exhaust mounts? Mine produced a similar sound from the back when the weld on my muffler support brace broke off...

Negative , the clunck noise comes from on top front of our S65 , 100 % sure !