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

[redpriest]

2011 M3 with DCT, 62.5k miles - I've never heard this clatter sound ever on cold start.

[FrankieP]

This is normal for the S65 motor. My car has done it for 5 years (with no issue) and almost every M3 that I have worked on has had this noise on cold starts as well.

[Beemdog]

"Normal" implies that they all make this sound. Some do, many don't.

[bradleyland]

I've been reluctant to post in this thread, but since reading so much about it, I've paid closer attention to my car on startup, and it makes this sound sometimes on cold start. Engines are mechanical. They make all kinds of sounds. This doesn't strike me as anything to worry about, and the anecdotal evidence points to that. Who has experienced a failure after hearing this sound?

[4corners]

IMO this happens after the engine oil has had time to drain out of the Vanos system. When started, until oil gets to everything, it makes the sound for a split second.

We also have the electronic oil stick. If you were able to check the oil before driving the car, and it's been sitting, you will likely get an incorrect reading because all the oil in the valve train has drained into the motor.

It's my guess that's why we have no dipstick. The car has to be run to get an accurate reading.

[///M Power-Belgium]

Originally Posted by bradleyland

I've been reluctant to post in this thread, but since reading so much about it, I've paid closer attention to my car on startup, and it makes this sound sometimes on cold start. Engines are mechanical. They make all kinds of sounds. This doesn't strike me as anything to worry about, and the anecdotal evidence points to that. Who has experienced a failure after hearing this sound?

The question is, what will it cause on long-term ?
It's realy a metallic sound ,and to create such a loud sound like metal on metal ,it just can't be healty for our S65...no way !

[bradleyland]

Originally Posted by ///M Power-Belgium

The question is, what will it cause on long-term ?
It's realy a metallic sound ,and to create such a loud sound like metal on metal ,it just can't be healty for our S65...no way !

I disagree. There's zero proof that it has any long term effect, and you can't make that assessment by sound alone. You simply cannot. "Metal on metal" doesn't mean a thing. If the force is insufficient to cause deformation, two pieces of metal can tap each other for many, many years before any appreciable wear will occur.

This thread is full of the blind leading the blind. I know what causes engine failures, because I've taken apart failed engines. I've rebuilt them so they work again. I've also seen motors run in conditions that -- if you think this little knock is bad -- would make your head spin.

[///M Power-Belgium]

Originally Posted by bradleyland

I disagree. There's zero proof that it has any long term effect, and you can't make that assessment by sound alone. You simply cannot. "Metal on metal" doesn't mean a thing. If the force is insufficient to cause deformation, two pieces of metal can tap each other for many, many years before any appreciable wear will occur.

This thread is full of the blind leading the blind. I know what causes engine failures, because I've taken apart failed engines. I've rebuilt them so they work again. I've also seen motors run in conditions that -- if you think this little knock is bad -- would make your head spin.

Not sure if you know that we are talking about our Vanos Gears creating this metallic clunck noise ?
Personal i'm thinking our Vanos Gears are no joke when making this metallic loud noise...so again not healty my friend and $$$$.....

[bradleyland]

Originally Posted by ///M Power-Belgium

Not sure if you know that we are talking about our Vanos Gears creating this metallic clunck noise ?
Personal i'm thinking our Vanos Gears are no joke when making this metallic loud noise...so again not healty my friend and $$$$.....

You don't know that it's the Vanos gears. I don't know that it's not. What we do know is that people report having this noise for tens of thousands of miles with no ill effects. Even if it is the Vanos gears making the noise, that doesn't mean they're about to fail.

It's a metallic tap. It sounds scary to you, but that's an emotion, not a mechanical condition. If you want to be an effective troubleshooter, you've got to learn to disassociate those two things. I've heard it in person, and IMO, it doesn't sound nearly as bad as it does in the video. I think this is a consequence of the way microphones respond to this type of noise. It sounds a lot like lifter knock to me, which sounds scary, but an engine can run 100k miles with lifter knock and never experience a failure.

Then again, I'm shouting in to the void here. Some people obsess over details that are irrelevant. Some people will spend thousands of dollars chasing a "problem" that is only a problem in their mind. If that's what you want to do, go for it, but I'll voice my (informed) opinion that until we have some causal link between this noise and a failure, it could very well be an exercise in tail-chasing.

[Stronie]

I posted a great video of mine. I'm certain this is what everyone is talking about. Can you guys confirm.

Also I've had this noise since day 1. Sounds terrible but I'm going to chalk this up as normal.

[///M Power-Belgium]

Originally Posted by Stronie

I posted a great video of mine. I'm certain this is what everyone is talking about. Can you guys confirm.

Also I've had this noise since day 1. Sounds terrible but I'm going to chalk this up as normal.

100 % sure It's the clunk noise,exactly the same as mine,but your is louder !
I posted your video also in this thread .

[///M Power-Belgium]

Originally Posted by bradleyland

You don't know that it's the Vanos gears. I don't know that it's not. What we do know is that people report having this noise for tens of thousands of miles with no ill effects. Even if it is the Vanos gears making the noise, that doesn't mean they're about to fail.

It's a metallic tap. It sounds scary to you, but that's an emotion, not a mechanical condition. If you want to be an effective troubleshooter, you've got to learn to disassociate those two things. I've heard it in person, and IMO, it doesn't sound nearly as bad as it does in the video. I think this is a consequence of the way microphones respond to this type of noise. It sounds a lot like lifter knock to me, which sounds scary, but an engine can run 100k miles with lifter knock and never experience a failure.

Then again, I'm shouting in to the void here. Some people obsess over details that are irrelevant. Some people will spend thousands of dollars chasing a "problem" that is only a problem in their mind. If that's what you want to do, go for it, but I'll voice my (informed) opinion that until we have some causal link between this noise and a failure, it could very well be an exercise in tail-chasing.

99 % sure it's the Vanos Gears #60 => http://www.m3post.com/forums/showthr...=996069&page=3

[bmwnukid]

Originally Posted by FormulaMMM

Please replace only one thing at a time or else we'll never get to the bottom of this...

Both my 6MT and DCT do it. Not unique to 6MT.

Guys,

I took my car tot he dealership because it was doing the same thing. My car is a 2009 DCT with 40K miles. I'll admit I seldome drive the car and the dealership seems to think it's because the sit in garage instead of getting driven. The dealership called in a case to PUMA and thier response was that they don't go by noises and if the car is working fine then no need to do anything. Talk about deminishing my product confidence (they aced that one). Anyway I've driven BMW for thirty years and it's time to move. I've owned every model except for a convertible and I've really really enjoyed the product but to wait until there is a catstrophic failure just doesn't seem eficiently feiseable to the consumer or the produce. good luck with this one as well as the bearing issue. By the way the car I mentioned is in my garage waiting for pick up with the rest of my weekly trash. WHEN HURTS THIS BAD ALL YOU CAN DO IS LAUGH!

[bradleyland]

Originally Posted by ///M Power-Belgium

99 % sure it's the Vanos Gears #60 => http://www.m3post.com/forums/showthr...=996069&page=3

Yes, but there was no failure there. They (effectively) replaced the Vanos gears to eliminate a noise that may or may not have a negative impact on longevity. That is my point: that this may or may not have a negative impact. There are plenty of high-mileage S65 motors in the wild, and Vanos gears have not turned up as a significant source of failure. If this noise actually caused any damage, we'd have seen it in the form of Vanos failures by now.

[bmwnukid]

Originally Posted by bradleyland

Yes, but there was no failure there. They (effectively) replaced the Vanos gears to eliminate a noise that may or may not have a negative impact on longevity. That is my point: that this may or may not have a negative impact. There are plenty of high-mileage S65 motors in the wild, and Vanos gears have not turned up as a significant source of failure. If this noise actually caused any damage, we'd have seen it in the form of Vanos failures by now.

I get that and agree to what you're saying however in the past many years ago BMW did what was know as servicing cars at various intervals and at that time if something seem to be problematic or had the potential to become problematic they would call it in and get the authorization to repair..... and I guess to some extent I expect the same thing and it's just not going to have. It could also be that those cars with the same noise could have been told the same thing and because of that may have accepted it as normal, but I'm not going to put myself in that predicament. Good to see it from another perspective though, thanks for that.

[lockeed]

Everyone has his own opinions. But to me, this isn't a "normal" sound at all. If my car did that, I'd be dissembling it piece by piece until I find the source... I couldn't stand it.

[///M Power-Belgium]

Originally Posted by bradleyland

Yes, but there was no failure there. They (effectively) replaced the Vanos gears to eliminate a noise that may or may not have a negative impact on longevity. That is my point: that this may or may not have a negative impact. There are plenty of high-mileage S65 motors in the wild, and Vanos gears have not turned up as a significant source of failure. If this noise actually caused any damage, we'd have seen it in the form of Vanos failures by now.

Look my point of view was and still is...Is it normal or not ?
Others above are stating it's normal ?!?! Well when i'm reading things like this my blood begins to boil !
So if this clunck noise is normal ,ok no problem with that !
But than there is one thing that we must remember ....to all the ///M3's who don't have the clunck noise => are not normal ,because the clunck noise is normal !
BS !
And when you are saying metal on metal doesn't hurt ,don't forget the Vanos Gears have some sprockets and making a loud and metalic noise !
Pic below in front the Vanos Gears .....Think twice !

[anom3]

+1.

this is exactly where i stand. yes, the car runs great... but this cant possibly be normal...

i love just about everything about the car... this is one of the things i hate about mine :/

Originally Posted by lockeed

Everyone has his own opinions. But to me, this isn't a "normal" sound at all. If my car did that, I'd be dissembling it piece by piece until I find the source... I couldn't stand it.

[bradleyland]

Originally Posted by ///M Power-Belgium

Look my point of view was and still is...Is it normal or not ?
Others above are stating it's normal ?!?! Well when i'm reading things like this my blood begins to boil !
So if this clunck noise is normal ,ok no problem with that !
But than there is one thing that we must remember ....to all the ///M3's who don't have the clunck noise => are not normal ,because the clunck noise is normal !
BS !
And when you are saying metal on metal doesn't hurt ,don't forget the Vanos Gears have some sprockets and making a loud and metalic noise !
Pic below in front the Vanos Gears .....Think twice !

Gears, sprockets, loud noises, OH MY!

Go tap two coins together. Hear how loud they are? Are you tapping very hard? Now go do the same with two sponges? Not very loud, eh? When metal taps, it's loud, even if it's not very hard.

"And when you are saying metal on metal doesn't hurt ,don't forget the Vanos Gears have some sprockets and making a loud and metalic noise!
Pic below in front the Vanos Gears .....Think twice!"

Yes, but you haven't the faintest clue what the actual mechanism that causes the noise is. There are gears and sprockets. Ok. What is making the noise, and how will it affect the wear characteristics of the Vanos mechanism? Has anyone documented any irregular wear in these components? Do you even know how Vanos works, or are you just staring at what appears to be a Rube-Goldberg machine from your perspective?

Vanos is actually really simple. The cam drive gear/sprocket is mounted to a helical cut gear that acts kind of like an adjustable spline. This mechanism is aligned axially with the camshaft. Cam phase adjustment is actuated by moving this gear in and out, again, inline with the camshaft's axis.

So, is the rattle due to lash in this helical gear? That would be bad. It would also be the exact problem that many BMW owners have experienced. It's well documented, and it doesn't go away after startup. Vanos gear lash can be heard in the RPM mid-range pretty easily. No one has reported that.

Another possible cause is actuator clatter. Vanos is actuated by a piston, which is what moves the helical gear. You can see a video of this actuator here. The actuator is moved by oil pressure, so it's a prime candidate for noises occurring at startup. There are observed oil pressure drops at startup, which occur concurrently with the noise.

The thing is, the actuator could tap on the end of that helical gear for hundreds of thousands of cycles and never do any damage, because:

1) It's tapping against a gear which is very, very hard metal.
2) The actuator and gear-end have a large surface area, so the force is spread over a large area.

If it is related to Vanos, my money is on this being an actuator noise. It's of the right frequency to coincide with camshaft rotation. As the cam rotates over the valve lifters, the aggregate cam profile (the combined cam profile of all valves) has "lumps" in it, which cause a varying amount of resistance. At low oil pressures, the Vanos actuator may be "pushed back" by these forces, causing a clatter that sounds like lifter knock. If it were gear lash in the Vanos gear, we'd have reports of mid-range Vanos rattle, and definitely more failures. Gear lash in the Vanos gears will cause failures (eventually) because of the number of wear cycles. Gear lash is always present, so the lash continues to worsen as the engine turns over at thousands of RPM. This clacking noise happens 8-10 times on startup, then goes away. That's less wear cycles in a year than in a couple of minutes of operation when compared to gear lash.

That's my theory anyway, and it's informed by my experience working with mechanical systems. If you want to chase it, go for it, but my advice to anyone fretting over this is to go take your car for a drive and forget about it. "Normal" is a statistical distribution; nothing more. Being outside normal doesn't automatically lead to failure, no matter how obsessed anyone here is with it.

[bradleyland]

Originally Posted by lockeed

Everyone has his own opinions. But to me, this isn't a "normal" sound at all. If my car did that, I'd be dissembling it piece by piece until I find the source... I couldn't stand it.

"Normal" is a statistical distribution. That is to say, it represents the situation that occurs "most" often. However, it does not indicate that there is a problem. Problems lead to failures. I've heard this noise on my car while parked in the garage by itself so it could echo off the walls. I have since listened to it from under the hood. I suspect that the noise is far more common than we expect (I didn't think mine did it for the longest time), but that most owners simply don't notice it. So maybe it is "normal" under the right circumstances.

[///M Power-Belgium]

Originally Posted by bradleyland

Gears, sprockets, loud noises, OH MY!

Go tap two coins together. Hear how loud they are? Are you tapping very hard? Now go do the same with two sponges? Not very loud, eh? When metal taps, it's loud, even if it's not very hard.

"And when you are saying metal on metal doesn't hurt ,don't forget the Vanos Gears have some sprockets and making a loud and metalic noise!
Pic below in front the Vanos Gears .....Think twice!"

Yes, but you haven't the faintest clue what the actual mechanism that causes the noise is. There are gears and sprockets. Ok. What is making the noise, and how will it affect the wear characteristics of the Vanos mechanism? Has anyone documented any irregular wear in these components? Do you even know how Vanos works, or are you just staring at what appears to be a Rube-Goldberg machine from your perspective?

Vanos is actually really simple. The cam drive gear/sprocket is mounted to a helical cut gear that acts kind of like an adjustable spline. This mechanism is aligned axially with the camshaft. Cam phase adjustment is actuated by moving this gear in and out, again, inline with the camshaft's axis.

So, is the rattle due to lash in this helical gear? That would be bad. It would also be the exact problem that many BMW owners have experienced. It's well documented, and it doesn't go away after startup. Vanos gear lash can be heard in the RPM mid-range pretty easily. No one has reported that.

Another possible cause is actuator clatter. Vanos is actuated by a piston, which is what moves the helical gear. You can see a video of this actuator here. The actuator is moved by oil pressure, so it's a prime candidate for noises occurring at startup. There are observed oil pressure drops at startup, which occur concurrently with the noise.

The thing is, the actuator could tap on the end of that helical gear for hundreds of thousands of cycles and never do any damage, because:

1) It's tapping against a gear which is very, very hard metal.
2) The actuator and gear-end have a large surface area, so the force is spread over a large area.

If it is related to Vanos, my money is on this being an actuator noise. It's of the right frequency to coincide with camshaft rotation. As the cam rotates over the valve lifters, the aggregate cam profile (the combined cam profile of all valves) has "lumps" in it, which cause a varying amount of resistance. At low oil pressures, the Vanos actuator may be "pushed back" by these forces, causing a clatter that sounds like lifter knock. If it were gear lash in the Vanos gear, we'd have reports of mid-range Vanos rattle, and definitely more failures. Gear lash in the Vanos gears will cause failures (eventually) because of the number of wear cycles. Gear lash is always present, so the lash continues to worsen as the engine turns over at thousands of RPM. This clacking noise happens 8-10 times on startup, then goes away. That's less wear cycles in a year than in a couple of minutes of operation when compared to gear lash.

That's my theory anyway, and it's informed by my experience working with mechanical systems. If you want to chase it, go for it, but my advice to anyone fretting over this is to go take your car for a drive and forget about it. "Normal" is a statistical distribution; nothing more. Being outside normal doesn't automatically lead to failure, no matter how obsessed anyone here is with it.

1- When replacing the Vanos Gears the clunck noise disappears .
2- The Vanos Gears are replaced by exactly the same Vanos Gears as when the car left out of the Factory .
3- So when thinking logic , pull out the problem and put back in the same problem .
4- And so why was the noise gone now when replacing with exactly the same Vanos Gears ?
5- And 4 was my question ???

[douglee25]

Mine does the noise as well.

Doug