I have been driving my 2007 Volvo S80 for about 3 years now. I had it passed down to me from my mother when my previous car just completely gave out. My mother took good care of the S80 when she had it; she kept up with the maintenance of the vehicle, got regular oil changes, and kept it in like new condition inside and out.
I, on the other hand, have not taken care of it as well as she did, but I haven't wrecked the vehicle or missed any oil changes.

My S80 has been making this awful, high-pitched noise for about 7 months. The noise is like a sharply blown whistle or a high-pitched whine.

It doesn't always happen; sometimes I can use the car and it won't make the noise at all, but this typically happens only when I haven't driven the car for around 24 hours. When it does start making the noise, it usually starts while I'm driving. Once it does start making the noise it will typically last all day, and 9 times out of 10 the car won't be making the noise the next day. (Until it randomly starts up again.)

It gets worse when you start to press on the brake and is the loudest when you come to a full stop. It slowly dies out when you accelerate, and completely goes away when you are accelerating at a high speed (like when I'm driving on the freeway).

I left my car dormant for about 3 months from around January until March. During this time I took it to the mechanic to have it checked out. Of course, it wasn't making the noise so the mechanic didn't know what the problem was. On top of that, when he did hear the noise, finally, he claimed to be unable to find the problem/unable to fix it.
As soon as I started using the car again on a regular basis, the noise started back up.

Sometimes the noise gets SO loud that I can hear it with the door closed, and when I have music playing. It makes it hard for me to use drive-thru windows, as I cannot hear anything when I open my window, even if it's someone who is standing right next to the car. It creates a huge nuisance to those around me, as every time I come to a stop or park anywhere, the noise can be heard from a pretty safe distance. I constantly turn my car off just so the noise will stop, which is becoming a huge inconvenience in more ways than one. For example, every time I turn the car off I no longer have use of my A/C or radio; it uses extra gasoline; it takes extra time to stop the car and start it again which causes an inconvenience, not only for me, but for other drivers.)

Has anyone had this problem with their S80 or their Volvo? Does this sound like a common problem? Does anyone possibly know what the issue might be or what I could do to fix it? Thank you, any help would be greatly appreciated!

 

When its making the noise, open the hood and pull out the oil dipstick. Does it stop?

 

I tried that, and it worked! the noise completely stopped. thank you so much for your help! do you also now how can I fix this issue?