[bsigaroudi]

Hi,
My new m235i has been making this un-welcomed noise while at cursing speed 40-70 miles/hr. I did a test drive with BMW shop foreman and he thinks it is coming from transmission. He does not think it is the turbo or fuel pump as the noise is still there when i let go of the gas pedal. He was not sure if it is normal or not, as he hasn't experienced with enough m235i yet. The car has about 700 miles and going up. I haven't, and don't plan to drive it past 4500 rpm until 1200 miles.
Has anyone else noticed this low volume high pitch frequency noise while driving with windows up and audio and air fan off?
it will be great if you could share your thoughts.

[JustinCredibleM]

Hi,
My vehicle never had this issue, so I am unfamiliar with what it could be with this car.

Is it a hissing noise like an air leak from something in the cabin or a hiss similar to cracking your window .5mm and having the outside air come in?

[bsigaroudi]

Hi Justin,
thanks for the reply. The same shop foreman test drove a similar brand new car from their lot today and told me he did not hear the same noise. So he asked me to bring it in so they can spend time on it with a BMW specialist-field rep. I am scheduled for end of this week. Will update as I know more about it.

[JS919]

I have the same noise on my M235i and my girlfriend's has it on her 320i. She had her car before me and called me once when she heard it. I was on the phone with her and could hear it over the phone. Then a couple weeks later I got my M235i, it was parked (turned off) in the driveway and I heard the noise while doing yard work. I recognized the sound from hearing it over the phone. So I started searching the car for the source and I found the area it was coming from. I couldn't figure out what it was though. Since then I noticed it usually happens when the car has been driven, then parked for a little while (up to 3 hours) then driven again. The noise starts shortly after turning it off and continues while parked. If you drive again within a few hours it makes the noise until the engine is fully up to operating temperature.

I even took a video of it making the noise.

It had been turned off for at least an hour. It comes from an area on the driver side of the engine block, down low near the front. It sounds kind of like pressurized water or air being released through a small port, kind of like whistling noise.

I don't think it's anything to be concerned with.

[kerm1t]

ill test it today, but i dont think i have this issue. all i hear it my turbo..

[SuitedUp]

Wow. It's probably just haunted.

[kerm1t]

nope never had this issue on mine

[bsigaroudi]

Wow, that is an interesting noise!
Mine does not make this noise, perhaps i have not noticed that yet.
For me it happens while driving at around 60-70 miles/hr, continuous low volume high pitch. It does not matter if the car is cold or not. When I hear that noise i shift into neutral and still hear it. Could that still be transmission related?

[aacabriolet]

Originally Posted by JS919

I have the same noise on my M235i and my girlfriend's has it on her 320i. She had her car before me and called me once when she heard it. I was on the phone with her and could hear it over the phone. Then a couple weeks later I got my M235i, it was parked (turned off) in the driveway and I heard the noise while doing yard work. I recognized the sound from hearing it over the phone. So I started searching the car for the source and I found the area it was coming from. I couldn't figure out what it was though. Since then I noticed it usually happens when the car has been driven, then parked for a little while (up to 3 hours) then driven again. The noise starts shortly after turning it off and continues while parked. If you drive again within a few hours it makes the noise until the engine is fully up to operating temperature.

I even took a video of it making the noise. http://<div class="youtube-playerCon.../iframe></div> It had been turned off for at least an hour. It comes from an area on the driver side of the engine block, down low near the front. It sounds kind of like pressurized water or air being released through a small port, kind of like whistling noise.

I don't think it's anything to be concerned with.

This is probably the water pump cooling the turbo down? I've heard the turbo BMWs do this when the car is shut off.

[kerm1t]

my car does make longer buzzing noise (sounds like its coming from the fuel pump) but nothing like the video. mine will buzz when shut off sometimes

[MilehighM3]

It's the A/C compressor. Advise your dealer of the noise with that video and they'll get it replaced.

[bsigaroudi]

Hi all,
It is more sounds like a jet engine which is noticeable more around 60-70 mph. Above that it stays the same and does not get any louder.
I am not sure if it is coming from the engine or transmission. A few days ago i had a 320i loaner and it did not make that noise at all. is this normal or something is definitely wrong with my car.
I had my car in the dealer for a day while BMW engineer from Germany was there but he could not hear the noise as it was a rainy day. He visits this center once a month. So i have to wait for him to do a test drive to see if he can figure out what is going on. Otherwise the car is a blast to drive.

[kerm1t]

does the sound go away in between shifts?

[MilehighM3]

Originally Posted by bsigaroudi

Hi all,
It is more sounds like a jet engine which is noticeable more around 60-70 mph. Above that it stays the same and does not get any louder.
I am not sure if it is coming from the engine or transmission. A few days ago i had a 320i loaner and it did not make that noise at all. is this normal or something is definitely wrong with my car.
I had my car in the dealer for a day while BMW engineer from Germany was there but he could not hear the noise as it was a rainy day. He visits this center once a month. So i have to wait for him to do a test drive to see if he can figure out what is going on. Otherwise the car is a blast to drive.

See my post above, recommend they check the a/c compressor. It's a somewhat common noise on the N55.

[darkerosxx]

Originally Posted by SuitedUp

Wow. It's probably just haunted.

Yes! Best comment ever, given the video.

[bsigaroudi]

Kerm1t,
it does not go away between shift. in fact when i hear the noise i put it in nutural gear, while driving, and noise still there.

[bsigaroudi]

MilehighM3, thanks for the suggestion. i will bring it up at my next dealer visit.

[bsigaroudi]

MilehighM3, would a/c compressor make noise even when a/c is not on?

[K99]

"My new m235i has been making this un-welcomed noise while at cursing speed"
Think you meant cruising but cursing is more apt!!!! :-)

[MilehighM3]

Originally Posted by bsigaroudi

MilehighM3, would a/c compressor make noise even when a/c is not on?

Yes it can. Is the sound the same as the video above? Engine off or running the noise can be the same, it's just heard differently due to the engine noise.

Regardless of the a/c button being activated the compressor can still engage if needed. There is actually no clutch on the compressor but rather a bypass valve that creates a restriction and pressure buildup as a result.

[bsigaroudi]

well, finally i was able to bring the car in while bmw regional rep was at the dealer. their diagnoses was "possible differential making noise". now dealer will submit this repair request to bmw na to get approval. will update this thread once i know for sure they will replace the part. dealer says that once they submit all testing data collected from my car to bmw na, they might analyze the data differently than the dealer and may ask for more testing. we will see how it goes next week.

[pikcachu]

ask them to put the LSD instead of the stock diff