[wholefoods]

Question to seasoned 335i owners:

I've had this car for about a week and when coasting on highway with speed dropping from around 130 to 110 kmh I get a very noticeable and annoying whistling sound - that really gets into my ears!

Please listen to these videos (preferably with headphones):

1 -

2 -

3 -

If I accelerate during this whistling interval the sound goes away, but the moment I let go of the gas pedal the whistle is back! Happens when both coasting or breaking.

My previous car was X3 35i with the same N55 engine but it never produced such a sound.

Does anyone know what the cause may be? Is there a fix to this?

Thank you for your input!

[gomichaelkgo]

Sigh, that is annoying. Hopefully you can faithfully reproduce it for the technician.

[TwinPowerF30]

Is this a 2014 with eco sail mode?

[wholefoods]

Nope - 2013

[BMW_F30]

Do you have the 8AT? This transmission has been known to whine for some people. Try shifting into N while decelerating and see if noise changes.

[Mobster1983]

It's hard to hear on the video, but it sounds similar to an issue I had last month with my M6. The dealer had the car for about three days before they figured out it was the power steering fluid pump. The entire pump and hoses had to be replaced.

Fortunately I have extended warranty still. :-) I would take it to the dealer sooner rather than later.

[JAYMAN420]

Did you ever find out why it was making that noise? My BMW X4 is making the same exact noise and its really annoying

[Dirk Diggler]

I have a 2012 F30 335i that makes the same noise... too much road noise to hear at your speeds though, mine is louder at around 60-90km/h. Sounds like either the rear diff or transmission whine. I don't think it's an issue if the noise doesn't bother you. Mine's very minor, and I doubt a passenger would ever notice unless I point it out.

[JAYMAN420]

Originally Posted by BMW_F30

Do you have the 8AT? This transmission has been known to whine for some people. Try shifting into N while decelerating and see if noise changes.

I have that same problem. When I shift it into N while decelerating the noise goes away and as soon as I put it back in drive it starts again. What does that mean??

Please help

[JAYMAN420]

Originally Posted by BMW_F30

Do you have the 8AT? This transmission has been known to whine for some people. Try shifting into N while decelerating and see if noise changes.

I have the same problem, but when I shifted it into N while decelerating the noise stopped. When I shifted back to drive while decelerating the noise continued. What does that mean?

[XxThe_RemedyXx]

Happened to me. Turned out to be a rear differential seal that was leaking. Happened at low speeds 15-20 MPH and letting off the accelerator.

[tardboi]

Another year old bump... does anyone else experience this? Mine makes the exact same noise at the exact speeds as the videos above. I never noticed it before, but recently had the transmission heat exchanger replaced, and the invoice states "Check trans fluid level" (but no invoice for a new transmission pan, so they couldnt have done it correctly). Thinking the fluid might be too low/high? Or.. maybe this is common and most people just dont notice it.

Oh, and in eco mode - when the trans disconnects, or whatever - noise goes away.

If its something to be concerned about I will try to get the dealer to do a fluid change or otherwise figure it out.

[SergioRamirez]

This exact noise happened to me. Any ideas???

[tardboi]

Well, I went back and fortunately had some old dashcam footage. Found that the noise was occurring before the transmission heat exchanger was replaced but I never noticed.. so, not too worried about fluid levels.

RPM has no effect on noise, neither does AC/fan.

So, it would have to be... the transfer case.

[StannisBaratheon]

Same noise in my 2016 340i. Very annoying and I haven’t figured it out. Tried putting tape over various seams and panels to see if it was just wind noise but still haven’t figured it out. My guess is transfer case.