[kneepuck]

Did a search but found nothing...

After the car has been driven, and is parked for a short term (say 3 hours or less), it makes a high pitch whistle noise when driving.

Facts:

-only happens when car has been driven and is still “warm”
-doesn’t happen on cold start like in the morning or if parked for a few hours
-sound is not rpm dependent and doesn’t correlate to acceleration or deceleration (pitch doesn’t change..just a weeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee when moving)
-sound only occurs while moving, not when stopped
-after driving a few minutes it completely goes away
-not from hvac. Happens with ac/heat on or off. Fan on or off.


Any ideas or anyone experienced the same thing?

[Thecastle]

It’s probably a PCV vent line. This is a common issue. Check for cracked lines especially those that are near the engine or that cross over the engine if you have a v8

[kneepuck]

Doubtful it’s a vent line. If so, why does it only do it after a warm start and goes away after a few minutes of driving?

Again, it is not rpm or engine dependent. When the car is moving and I throw it in neutral and coast it, it’s still there. Same pitch until I come to a stop.

[550iBM3]

Had the same issue, except it would only go away while driving, at idle, high pitched noise. Here's how to check if it's breathers and/or lines, while it's idling, if it is making the noise, just pull the oil cap off.... if it goes away it's the breathers or lines.

[kneepuck]

I have zero noise when it’s not moving. Only when it’s moving and sound stays even if I shift to neautral and let it coast at idle

[Gulfstream550]

I have the same whistle sound and pretty much conditions when it happens. Only happens when the car is moving. Like the OP, I feel like it happens when the car isn’t fully warm or completely cold. Mine seems to stop once fully warmed.

[Gulfstream550]

Originally Posted by kneepuck

Did a search but found nothing...

After the car has been driven, and is parked for a short term (say 3 hours or less), it makes a high pitch whistle noise when driving.

Facts:

-only happens when car has been driven and is still “warm”
-doesn’t happen on cold start like in the morning or if parked for a few hours
-sound is not rpm dependent and doesn’t correlate to acceleration or deceleration (pitch doesn’t change..just a weeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee when moving)
-sound only occurs while moving, not when stopped
-after driving a few minutes it completely goes away
-not from hvac. Happens with ac/heat on or off. Fan on or off.


Any ideas or anyone experienced the same thing?

do you happen to use a cigarette lighter phone charger?

[kneepuck]

Originally Posted by Gulfstream550

do you happen to use a cigarette lighter phone charger?

Nope, almost never charge my phone in the car. It only happens after driving, then parked for couple hours where car isn’t completely cold, then the first few minutes of driving again.

[top ramen]

Might be your pcv/ccv.

Does it sound like what's in the video at 58s.

[kneepuck]

Definitely not that. I have an e90 with a broken PCV in the valve cover before so I’m familiar with that failure.

[Gulfstream550]

Originally Posted by kneepuck

Nope, almost never charge my phone in the car. It only happens after driving, then parked for couple hours where car isn’t completely cold, then the first few minutes of driving again.

Good to know, I think i may have solved my issue. I saw a post of reddit about how the usb style car chargers omit some weird frequencies. I unplugged my charger from the "cigarette lighter" port and haven't heard the whistle since. I'll report back if anything changes.

[Granrey]

@ kneepuck

My car (2009 F02 750Li) does exactly the same thing!!!

Did you ever find the cause of this mysterious symptom?

[steveg959]

kneepuck hello did you ever fix the whistle ? i’m having exact same issue right now , appreciate your help please

[steveg959]

kneepuck did you solve this please it’s driving me nuts i can’t find out what it is ? kneepuck ?