high pitch sound during acceleration - e92 M3

[xfactor]

Hi Guys,

Just started to get a new high pitch sound (like a hollow whistle), when I slightly press down on the accelerator. It's somewhere around 3-3500 RPM (specifically in 3rd/4th gear). When I press pass the point the sound goes away, it's only when I hold on to that point in throttle the sounds remain. I have a appt set-up at the local dealer for next week, but was curious to see if anyone have gone through this or have a clue on what's going on.

Thanks in advance,
-a

[abehwang]

normal sounds

[disapr]

Mine is really bad about that...

You're fine.. The dealer will just take it for a joy ride.

[Green///Hell]

Originally Posted by disapr

Mine is really bad about that...

You're fine.. The dealer will just take it for a joy ride.

Well yeah lol the SC will give you that awesome whistle all the time

[xfactor]

Originally Posted by Green///Hell

Well yeah lol the SC will give you that awesome whistle all the time

Hmmm, weird that it just started to happen. Maybe I'll read around a bit, don't want to waste time at the dealer if they're not going to find anything.

[jphughan]

Originally Posted by Green///Hell

Well yeah lol the SC will give you that awesome whistle all the time

Damn, I was going to say that!

[TxFeatFan]

Is your GF in the passenger's seat?

[xfactor]

Originally Posted by TxFeatFan

Is your GF in the passenger's seat?

haha, what? Are you missing a smilie or two?

[TxFeatFan]

[GIdriver]

Originally Posted by xfactor

Hi Guys,

Just started to get a new high pitch sound (like a hollow whistle), when I slightly press down on the accelerator. It's somewhere around 3-3500 RPM (specifically in 3rd/4th gear). When I press pass the point the sound goes away, it's only when I hold on to that point in throttle the sounds remain. I have a appt set-up at the local dealer for next week, but was curious to see if anyone have gone through this or have a clue on what's going on.

Thanks in advance,
-a

Normal

[xfactor]

I can get normal, but all the sudden after 3 years. Doesn't seem too normal, that's what's perplexing me.
-a

[disapr]

Maybe you can make a recording of it and post to youtube for us to hear.

[sameh]

Heat shield needs tightening. Search the forum "heat shield" you'll find a thread just like that but on different RPM.

[Templar]

I've gotten it too occassionally. I've read it's normal, read it could be the heat shield, etc. I've never heard anything really bad coming of it, so I never bothered to have it looked into.

This car makes some noises, so I take everything in stride.

[E92Mazing]

i just took the car in for service since i had a grinding sound (tire rubbing on plastic) when I'd coast or brake after it was warmed up. Sounded awful. They checked the wheels/brakes/dust shields for rocks/e brake/exhaust/ and finally said it was a heat shield rubbing against the drive shaft... got the car back same day and the rubbing is definitely gone but when i coast in any gear between 5-6k rpm, I have a very high pitched sound.. nothing under acceleration. This I can live with since I don't normally drive the car at those speeds, and when I am... my foot is usually on the gas!

[xfactor]

Just to put up more info for future searchers:

Took it into the local dealer today. The techs take it for drive and couldn't figure out where the noise is coming from. Take it again for a second road test and after the fact they put it up on the hoist and pin point it to the fact that the sound is coming from the differential.

Tells me that I need to change the differential to get rid of the noise. Mine is out of warranty by 5xxx miles. Don't think I want to pay 5K (parts and labour) to fix this now. Plus I want to get a second opinion on what the noise is and why it is happening.

They said that they have never heard the noise from another 3 series or M3, but don't think that these guys get that many M3s into their bay. I want to know, how that noise got there (wear and tear or abuse), so I'll try to find out before I decide on what to do. Now you know, don't know the noise is normal or not (as other M3 owners suggest here), but according to the techs who inspected my car; not normal.

[Superfly_M3]

how about flushing the differential and putting new oil in? seems like a small, simple thing to try to get rid of the noise.

[xfactor]

Originally Posted by Superfly_M3

how about flushing the differential and putting new oil in? seems like a small, simple thing to try to get rid of the noise.

Absolutely. Going to do that this weekend (fingers crossed)

[MrD1198]

My X5 would do something similar to that. It would whistle like there was a vacuum leak but only at one position of the throttle. If I let up or pushed further on the throttle it would go away. No idea what it was...

[GIdriver]

Originally Posted by xfactor

Just to put up more info for future searchers:

Took it into the local dealer today. The techs take it for drive and couldn't figure out where the noise is coming from. Take it again for a second road test and after the fact they put it up on the hoist and pin point it to the fact that the sound is coming from the differential.

Tells me that I need to change the differential to get rid of the noise. Mine is out of warranty by 5xxx miles. Don't think I want to pay 5K (parts and labour) to fix this now. Plus I want to get a second opinion on what the noise is and why it is happening.

They said that they have never heard the noise from another 3 series or M3, but don't think that these guys get that many M3s into their bay. I want to know, how that noise got there (wear and tear or abuse), so I'll try to find out before I decide on what to do. Now you know, don't know the noise is normal or not (as other M3 owners suggest here), but according to the techs who inspected my car; not normal.

You don't sound too confident about your dealer. Any chance you can get a second opinion? I hear some sort of whistle since day one, although not sure at what rpms, will pay more attention to it now. What I hear in my car is very unlikely that is diff related, appears to come from the engine bay, and as I said before, from day one. Not sure what's happening to yours. A diff fluid change will not hurt. Please keep us posted.

[ploo]

[xfactor]

Originally Posted by GIdriver

You don't sound too confident about your dealer. Any chance you can get a second opinion? I hear some sort of whistle since day one, although not sure at what rpms, will pay more attention to it now. What I hear in my car is very unlikely that is diff related, appears to come from the engine bay, and as I said before, from day one. Not sure what's happening to yours. A diff fluid change will not hurt. Please keep us posted.

I'm not that confident in this particular dealer due to the fact they spent a lot of time trying to identify the issue and once they did; they were not able to provide a reason why the issue was happening.

I was able to find this from the net and it appears to be the issue for my situation.

A BMW differential's most common wear item are the output bearings. Output bearing wear is characterized by a hum or whine from the back of the car that will become audible between 3000-4000 rpm, usually more noticealbe in fifth gear at a constant cruising speed. The noise will stop or change when you lift your foot from the accelerator pedal and may also change as the suspension rebounds from dips and valleys in the roadway. The perceptability of the noise is dependent on the load on the bearing The noise may also stop entirely above a given rpm. Also, many cars with differentials showing this wear have gone another 50,000 miles with this noise and no further, so it's not necessarily something that needs to be addressed right away. But the longer you let it go, the more likely it is that other parts, such as the expensive ring and pinion gears, may wear out as well....

source: http://bmwnut.blogspot.com/2006/03/b...iagnosing.html

I have consulted with another local BMW tuner shop and they iterated that I should do a diff oil flush and then take it from there. I'll keep you updated on the developments.
-a