It is driving me crazy, it almost sounds like an air compressor running or an electric motor. It doesn't happened all the time, just most of the time. I don't hear it when the engine is cold or I can get it to stop if I rev over 5k.
I thought it was a vaccum leak at first, but now I have no idea....

 

Have you recently installed anything?

 

No i haven't right now it only has intake. I replaced spark plugs a few months ago

 

Just curious what you found out about with this. Mine has been making a similar noise, but its at the front of the engine. It seems to be my belts, and hub says its time to replace them anyway. Im hoping this will fix it.

 

I have not figured it out yet. It has not done it since it got cold so I kinda forgot about it till you said something. I need to replace my belts as well, I am have alot more noise from them lately. I just keep meaning to buy new lightweight pulleys when I do buy belts.