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

[///M Power-Belgium]

Originally Posted by ivad32

What is the issue?

.

[anom3]

thanks for the input, by the sounds of it you are far more knowledable then most.

the one thing i would like to mention regarding the possibility of an 'electrical glitch' is that this happens only on first cold start. start -> grind -> off -> start -> no grind. if this sequence is done even seconds apart, there will be no grind the 2nd start. it will only occur again if the car is allowed to let sit for a number of hours (4+ seams to be the mark... although by 6+ the noise is there 100% for sure).

wish i could push start the car on my own... major pain in the butt

the car has been sitting for about 48 hours today. when the gf gets home from work im going to have her start with my head under the hood so i can see if i can at lease get a sense of the general direction the noise is coming from.

once again, thank you very much for the input, its appreciated.

Originally Posted by SenorFunkyPants

Interesting read. My 2009MY car doesn't make this noise no matter how long my car stands - so no, every car doesn't do it
The way the sound occurs (cold start after standing) does seem to point to some sort of VANOS issue, although its hard to visualize what sort of internal event could be happening to produce such a sound. AIUI the VANOS is in the default position at start up and tickover, the only parts that would require instant oil pressure are the timing chain tensioners - 75 psi should be more than enough to work the tensioners and if they were the cause why doesn't it make the noise the instant the engine starts? But if replacing VANOS components fixes the issue then it does sounds like the most likely fix
Regarding the starter motor - although it sounds unlikely, the grinding does actually sound like the noise you get if you try and start a car that is already running, where the starter gear hits the already turning flywheel teeth. Pressing the brake pedal in a DCT (clutch pedal in MT) releases the interlock and allows the starter to turn to start the engine - I guess there could be some sort of electrical glitch that causes the starter to momentarily try and re-engage despite having already started the engine?
A push start test (in an MT) is the next step to see if it eliminates this possibility.

[anom3]

in order to further investigate the possibility of an electrical glitch / fault... later today i will try disconnecting the battery for 30+ mins. reconnect. start. to see if the noise occurs again.

Originally Posted by anom3

thanks for the input, but the sounds of it you are far more knowledable then most.

the one thing i would like to mention regarding the possibility of an 'electrical glitch' is that this happens only on first cold start. start -> grind -> off -> start -> no grind. if this sequence is done even seconds apart, there will be no grind the 2nd start. it will only occur again if the car is allowed to let sit for a number of hours (4+ seams to be the mark... although by 6+ the noise is there 100% for sure).

wish i could push start the car on my own... major pain in the butt

the car has been sitting for about 48 hours today. when the gf gets home from work im going to have her start with my head under the hood so i can see if i can at lease get a sense of the general direction the noise is coming from.

once again, thank you very much for the input, its appreciated.

[///M Power-Belgium]

Originally Posted by anom3

thanks for the input, by the sounds of it you are far more knowledable then most.

the one thing i would like to mention regarding the possibility of an 'electrical glitch' is that this happens only on first cold start. start -> grind -> off -> start -> no grind. if this sequence is done even seconds apart, there will be no grind the 2nd start. it will only occur again if the car is allowed to let sit for a number of hours (4+ seams to be the mark... although by 6+ the noise is there 100% for sure).

wish i could push start the car on my own... major pain in the butt

the car has been sitting for about 48 hours today. when the gf gets home from work im going to have her start with my head under the hood so i can see if i can at lease get a sense of the general direction the noise is coming from.

once again, thank you very much for the input, its appreciated.

When my wife started the car i held my hand on front-top of the manifold,and i could feel the vibrations of the clunk through my hand !
But locating the clunk noise so close to the engine ...sadly i could not ,no way !

[Race_Doc11]

Thank you so much for the input. Great information.
For the last few days I have been starting the car right away trying to convince myself that the Brakes procedure has nothing to do with it and I have been getting the clunk every single time. It is not as loud as most of you here it became quite since I got the vanos tensioners changed 2 years ago. Today I decided to try the brake procedure again and there was NO sound what so ever!!!! My mind is refusing to believe that the brakes have any thing to do with it but it works...In my case what bothers me the most that I can’t figure out the cause. I can live with it as long as I know what it is.

Originally Posted by SenorFunkyPants

Interesting read. My 2009MY car doesn't make this noise no matter how long my car stands - so no, every car doesn't do it
The way the sound occurs (cold start after standing) does seem to point to some sort of VANOS issue, although its hard to visualize what sort of internal event could be happening to produce such a sound. AIUI the VANOS is in the default position at start up and tickover, the only parts that would require instant oil pressure are the timing chain tensioners - 75 psi should be more than enough to work the tensioners and if they were the cause why doesn't it make the noise the instant the engine starts? But if replacing VANOS components fixes the issue then it does sounds like the most likely fix
Regarding the starter motor - although it sounds unlikely, the grinding does actually sound like the noise you get if you try and start a car that is already running, where the starter gear hits the already turning flywheel teeth. Pressing the brake pedal in a DCT (clutch pedal in MT) releases the interlock and allows the starter to turn to start the engine - I guess there could be some sort of electrical glitch that causes the starter to momentarily try and re-engage despite having already started the engine?
A push start test (in an MT) is the next step to see if it eliminates this possibility.

[anom3]

worth mentioning, just tried the following, and the noise was still there:

under the CAS module, there is a software setting KOMFORTSTART (something along those lines, dont have my other laptop here right now).

this setting basically makes it so that instead of having to "hold down" the start button while the motor is started, all you have to do is quickly press it and the computer will start the motor on its own.

akin to turning and holding the key in a 'regular' style ignition.

this basically gives you complete control of the starter.

i tried disabling the comfort start as bmw calls it (its default to enabled).

noise was still there

[///M Power-Belgium]

Originally Posted by racedoc11

Thank you so much for the input. Great information.
For the last few days I have been starting the car right away trying to convince myself that the Brakes procedure has nothing to do with it and I have been getting the clunk every single time. It is not as loud as most of you here it became quite since I got the vanos tensioners changed 2 years ago. Today I decided to try the brake procedure again and there was NO sound what so ever!!!! My mind is refusing to believe that the brakes have any thing to do with it but it works...In my case what bothers me the most that I can’t figure out the cause. I can live with it as long as I know what it is.

Same here with the"brake procedure" but works only with DCT cars !
I said it before on here knowing that it sounds realy unbelievable !
Note; Build year of the engine is no specification for the clunk noise,because i know someone with a 6 months old engine and has the clunk noise too !

[SenorFunkyPants]

It used to be that if you kept pressing and releasing the brake pedal with the engine off you would eventually bleed off the vacuum in the brake servo reservoir (don't know if this applies to the E9x M3).
I'm certainly not an expert on how the VANOS works but I suspect that the manifold pressure enters into it.
Whether the brake servo attempting to restore its vacuum (from the low air pressure in the engine) could affect the VANOS is a possibility I guess.
Can't think of anything other way the brake system could have an effect on the start up cycle.

[Race_Doc11]

I discovered something wired the other day. I usually turn the ignition on then try the brake procedure then push the start button again to start the car but on random occasions the car will start by just pressing the brakes . It doesn't happen all the time but randomly. I'm also the opposite of everyone; when my car is not driven for a while there is no noise. But if I drive it everyday the noise will come back all it takes is a couple of hours to cool down then boom it will do it.

Originally Posted by ///M Power-Belgium

Same here with the"brake procedure" but works only with DCT cars !
I said it before on here knowing that it sounds realy unbelievable !
Note; Build year of the engine is no specification for the clunk noise,because i know someone with a 6 months old engine and has the clunk noise too !

[FormulaMMM]

Originally Posted by racedoc11

but on random occasions the car will start by just pressing the brakes .

What??

[Race_Doc11]

Exactly! While my ignition is on if I press the brake it will start not all the time but random like I said. I have never knew until it happened by chance. I think this might support the electric glitch theory

Originally Posted by FormulaMMM

What??

[Rupes]

Man, times like these I wish these forums had some actual BMW engineers on here to explain these concerns. This one especially sucks because you can't duplicate the problem without waiting 6+ hours.

[anom3]

so...

i just walked back in the house.

i just removed the intake manifold for the first time, fairly straight forward.

now am waiting for my gf to come home from work so she can start the car while i have my head under there.

hopefully this will give me a better idea of where the noise is actually coming from.

will keep everyone posted.

(sorry for the blur, iphone camera is shit)

[///M Power-Belgium]

Originally Posted by racedoc11

I discovered something wired the other day. I usually turn the ignition on then try the brake procedure then push the start button again to start the car but on random occasions the car will start by just pressing the brakes . It doesn't happen all the time but randomly. I'm also the opposite of everyone; when my car is not driven for a while there is no noise. But if I drive it everyday the noise will come back all it takes is a couple of hours to cool down then boom it will do it.

So when i get this right...
1- Keyfob in
2- Brake procedure (tapping the brake )
3- And while tapping the brake pedal the car starts without pushing the start/stop engine button ?!?!
I believe you ! But never i heard or saw it before !
And personal i think this is not normal , strange things are going on with our cars ?!?!It 's almost hocus-pocus and have no explenation for it !
BTW...had or has your car some coding ?

[///M Power-Belgium]

Originally Posted by anom3

so...

i just walked back in the house.

i just removed the intake manifold for the first time, fairly straight forward.

now am waiting for my gf to come home from work so she can start the car while i have my head under there.

hopefully this will give me a better idea of where the noise is actually coming from.

will keep everyone posted.

(sorry for the blur, iphone camera is shit)

Just came back from work , and i'm curious if you will be able to locate the clunk noise,because i was not ,i thought and felt the vibration on front top of the manifold but was not able to say that i found the right spot of the clunk !
I had the impression the closer to engine the harder it is to locate the clunk !
Anaway hope that you have more luck than me !
Also i can see that your oil cap is leaking ,do you know that there is new type of oil cap with different part number ? (stops the leaking )

[anom3]

we will see how it goes, still have to wait about 2 hours for gf to come home.

oil cap was replaced about a month ago not leaking anymore.

Originally Posted by ///M Power-Belgium

Just came back from work , and i'm curious if you will be able to locate the clunk noise,because i was not ,i thought and felt the vibration on front top of the manifold but was not able to say that i found the right spot of the clunk !
I had the impression the closer to engine the harder it is to locate the clunk !
Anaway hope that you have more luck than me !
Also i can see that your oil cap is leaking ,do you know that there is new type of oil cap with different part number ? (stops the leaking )

[///M Power-Belgium]

Originally Posted by anom3

we will see how it goes, still have to wait about 2 hours for gf to come home.

oil cap was replaced about a month ago not leaking anymore.

Ok thanks for the info man ! Will be back on here too !
BTW...the new type of oil cap looks different than your's !
On here you can see in # 20 pic of the new type of oil cap and in # 1 are the new/old part numbers > http://www.m3post.com/forums/showthread.php?t=704497

[anom3]

oh you are right about the oil cap.

mine does not look anything like that.

it was replaced because the old one was falling apart. i think they just ordered the same part that was there in the first place.

will look into it, but i can say for sure, right now, its not leaking at all... probably because its brand new. if it starts ill order the new designed one.

[Minator]

There is a SB on the oil caps...makes no difference if it is old style or new...you CANNOT turn the cap upside down after removal...only lay the cap down in upright position when removing!....I have the SB somewhere..

For what its worth with the clunk and rattle cold start issue...my '09 did it random and my '13 (low miles) will rattle on cold start intermittently..clunk seems to be gone if I tap brakes?

I'm going to try a little RPM before I shut it down and see what happens maybe that will shoot some oil up into vanos gears/chain?....

I mean if BMW could figure out the oil cap why is there no SB on this funky noise.

[anom3]

so i just had my gf fire up the motor with my head under the hood.

have to admit, with the number (not necessarily the volume) of noises its VERY difficult to pinpoint where the noise was coming from.

i had a feeling it was located somewhere under the drivers side valve cover.

but like i said, so many noises, really hard to say.

i can for sure rule out the following tho:

secondary air pump
alternator

but yea, it really sounded like something from where the valves are located on the drivers side.

also, we (gf actually) turned the motor off almost right away. proceeded to start again. not a whisper of the noise.

also, having the motor idle. 0 trace of the noise.

so its clearly a cold start, first time only noise...

*sigh*... any ideas?

[///M Power-Belgium]

Originally Posted by anom3

so i just had my gf fire up the motor with my head under the hood.

have to admit, with the number (not necessarily the volume) of noises its VERY difficult to pinpoint where the noise was coming from.

i had a feeling it was located somewhere under the drivers side valve cover.

but like i said, so many noises, really hard to say.

i can for sure rule out the following tho:

secondary air pump
alternator

but yea, it really sounded like something from where the valves are located on the drivers side.

*sigh*... any ideas?

Like i said , it's very hard to pinpoint this damn clunk noise that close to the engine !
Back to off...........

[anom3]

here is a video i recorded with the intake manifold off and my head under the hood.

the sound is quite distinct here, and sounds 'worst' in real life.