HELP! My car has tinnitus!!
My engine is making a really loud whistling sound even though it is off and the key is out!
The car hasn't been running for over 3 hours so the engine is now cool enough to touch but still slightly warm. I was washing it and noticed a whistling noise. I put my ear to the bonnet and concluded it was coming from the car, so I opened it up and sure enough, the sound was coming from the bottom right section of the engine where the video below shows.
Sorry the video isn't the best of quality, I used my Android Phone to take it. The whistling was intermittent. At one point (most of the time on this occasion) it was very loud and high pitched, but then it would go away all together for a few seconds then come back quieter and gradually louder to the volume and pitch the video shows.
What is making the sound and why?
Have you had any experiences like this? Is it a problem?
Your help would me much appreciated!
2009 E90 BMW 330d 60k miles.
EDIT: Car is now at 80k miles and I haven't caught it whistling again so I'm not concerned, just very curious!