My 95' Volvo 850 Turbo has been making this high pitched noise (it is NOT a grinding/thumping/clicking noise, just listen to the recording). It used to only make the noise when I was turning a sharp right, now it comes randomly, most often when more than one person is in the car and I am going high speeds (freeway). Sometimes it can go for periods of 20+ minutes. When it does start making the noise, it is loud enough that I can't talk to the person sitting in the passenger seat. I was driving to Wingstop the other day and it made the noise the whole way there, but not once on the way back. You can feel the floor vibrating when it makes the noise, I am unable to tell if it is coming from the back or the front. When I am on the freeway and brake (not too hard) the noise completely stops, but as soon as I stop braking it comes back. But then, I was on side streets the other day, and it only made the noise when I started to break...no idea what i could be. Seems almost to change when the weight of the car moves?

My mechanic used to work for Volvo and he knows his way around a car.. He replaced both a control arm that was damaged and fixed my suspension, but it still makes the noise. Finally I recorded it on my iPhone and played it back for him. He was shocked and had no idea what it was and is going to take a another look underneath the car again this afternoon. I am turning to the internet to see if anyone has any ideas.

Took the recording from my iPhone and put it on my computer. You can hear the noise here. I boosted the volume in goldwave so it should be easy to hear. It is 5x as loud than it sounds in this recording.

http://uploads.mailboxdrive.com/carnoise2.mp3

Any and all ideas welcome..

 

I am going out on a limb here but is sounds like a piece of trim is vibrating with the wind. It would be a small piece to hit that harmonic resonance. Finding it will be hard. You may need a second person in the car moving around, head twisting to locate it. To me it does not sound like something mechanical.

 

...just to add, look for anything that can vibrate. e.i. heat shield, firewall, exhause shields under the car, Metal, plastic, etc.

 

I thought that as well at first but another thing that makes me think it is not: It used to make the noise when I was turning to the right (whether it be a long wide turn on the freeway or a sharp turn on a street) , and it would stop as soon as I straightened out. And sometimes, the other way around. Unless you think that could still be related to the wind idea?

 

Wheel well tubs?

Does it happen when your going slow or fast? Does it happen when you hit a certain engine speed? Next time it goes, speed up or slow down.

What do you hear with your windows rolled down?

 

It's not really a "certain" engine speed, but 99% of the time it happens if I am driving on the freeway or making a turn, I don't know if it has ever happened while I was just driving straight on side streets. When making a sharp turn, if I have my foot on the brake while I'm turning, it won't make the noise, but as soon as I take my foot off (or straighten out) the noise will stop. It happens less frequently than several months ago, but when it does happen, the sound is worse than ever before. If I had to guess I would say its not coming from the engine. You can hear outside when you roll the windows down, but it sounds like its coming from underneath the car.

That recording I have up, at the very end when the noise stops, that me straightening out after going up a turning hill.

 

...a bit confusing

 

Not hard enough to slow down considerably but enough to shift the weight of the car and make the noise stop

 

Axle bearing failing? Stepping on the brake/turning would change the stresses on it.

Easy enough to pop the bolts out to inspect. Any foreign matter/scratching/scoring could lead to screeching and vibration.

 

That's pretty wild! Definitely something hitting its resonant frequency. Has this car been in a collision recently? Is there any significant event that correlates to when the noise first appeared?

You said braking lightly makes the noise go away; what about just letting off the gas? Does that do it too? Is it only at highway speeds?

Does rolling all the windows down make it go away?

If not, I would look in the engine compartment (all over the car actually) for anything loose. Things I thought of are the metal brake/fuel lines under the car. Any/all exhaust heat shields. Also the AC drier in the right front corner of engine bay area; if the bracket broke it might sound like that.

If it's definitely the brakes that make it go away, then look over the drive train carefully; something is loose!

Let us know what you find.

 

Yes an odd one.
If you weave back and forth after it starts does it change?
Does opening the sunroof(If it has one) change the noise?
Do you have an OEM wind deflector on it?

 

Thanks for all the responses guys! Big help. I'm going to shoot these ideas to my mechanic. I'll try and address all your questions.

-I was also thinking that braking was changing the stress on certain parts of the car and that's why it was stopping

-When the noise comes in I can feel the floor vibrating beneath my feet, but my friend in the backseat said he thought it was coming from underneath him. It's so high pitched that it's hard to pinpoint it.

-Rolling down the windows does not change the noise (I haven't tried the sunroof but it sounds like it is definitely coming from underneath the car).

-Letting off the gas does not remove the noise, but it does eventually go away as I slow down to a stop.

-It only does it at highway speeds or if I'm turning (although recently it hasn't done it as much while I was turning)

-I do not have a wind deflector.


The first thing that popped into my head when I heard it was that it sounded like two pieces of metal rubbing together (kind of like when youre breaks squeak). Not grinding as you can obviously tell, but almost like two things brushing each other at a high speed. Maybe I am wrong, not exactly sure what metal would sound like doing that. Someone said possible bad wheel bearing?

Something important I forgot to mention. I was driving it to the mechanic on the freeway yesterday and I could hear the noise VERY faintly. I had to turn off my stereo to hear it. It was quickly/lightly cutting in and out, wasn't going constantly.

 

Try messing with the hood to make sure the hood is not making the noise. Or put a rag between the rubber stops and the hood and close it. Then see if the noise stops.

 

Did some testing, had my friend sit in the back left seat while I winded back and forth on our street and it started to make the noise. Then I had him leave the left door open so we could hear it better. It would only do it when I weaved to the right, and it is definitely coming from underneath the car on the left side. It did not matter if I was accelerating or just letting the car roll. And we were only going 20, so it can't be a wind related issue.

Really annoying thing is that we parked and went out later to do the same thing, and it wouldn't make the noise

 

Dry wheel bearing? Next time it does it, put the car in neutral and let it roll. IF it stops, you have eliminated the transmission as a source

 

This might sound stupid but had similar on a Ford .
tiny stone trapped between disc and pads.

 

This post is eleven years old. He probably sold the car by now.

 

Does it sound like R2D2 screaming?