Hello all!
The weather got really cold recently and I immediately noticed a high pitched whining sound at 2K rpm's while driving. I think it might be weather related but maybe a coincidence? It'll warm up again in a couple of days so I'll see if it goes away.
I've included a video, please see the link at the end of the post.
Basically while driving, when the engine RPM's reach 2K i hear a high pitched whining sound from inside the vehicle. I rolled the window down and can hear it louder, outside the vehicle too.
To rule a few things out, I had the vehicle in park and got it up to 2K rpms and it didn't do it. I have to be driving. Also, while driving it does it on all gears, and OD. The sound goes away when the vehicle has been warmed up to 190F and/or I've been driving for 10 minutes or so. It does it in all modes, 2WD/AWD/4WD.
I did some research and was able to find a 98 4Runner with same issue and the comment from the OP said it turned out to be the exhaust but didn't specify. It does sound like some sort of resonance but I don't know where it might be, something touching the exhaust system? And why only when cold?
Any insight is much appreciated.
https://www.youtube.com/watch?v=ByPnHGO-uVQ&feature=youtu.be