I posted a thread up on another Volvo forum but I'd thought i stop by here and see if anyone has had a similar problem and know what to look for. I'll post the original thread link.

 

When I first read this post, that you posted a video trying to share the sound, I thought, "Why do people do the videos? We can't hear the sound through their cheap mic, compressed video, and our cheap .03 cent speakers." I'm actually surperised of how well it turned out.

Any way, the sound is horendas. I was expecting a buzz, that was more like a howling growl. What you should do is take the serpentine belt off and start the car (belt can be removed in seconds). If the noise is still present, the problem is in the timing belt path. If the noise goes away, it's in the serpentine belt path.

Now, if the problem is in the serpentine path, no real big deal. If it's in the timing belt path, dial 911. Get it fixed like - TODAY. It's likely a bearing on one of your rollers about to totally fail and toss your timing belt, which will pretty much destroy your motor. You may want to find out when the last time the timing belt was replaced with idler and tensioner roller.

Other than that, congrats on getting a very nice model car. Very good car to own.

 

Also, when I looked at your pic of the location I could not help but notice the oil near the fuel lines. That is not good. Have you had the PCV system checked since you purchased the car?

 

Picture is not my car i just found it online.

Found the problem it is a vacuum leak. Right under the thermostat housing there is a black hose it runs behind the manifold the hose itself split a little a tiny bit and it's causing the noise. I was fishing around the engine with the car running with a screwdriver moving all hoses around and when i moved this specific hose the noise stop. Problem is the hose is very hard to get to to properly replace it with a new one without removing the power steering pump and thermostat housing. I noticed if i push on the hose either up or down on it slightly the noise stops so I'm going to use a tie wrap a long one so i can maneuver it in the tight space and around the split area of the hose and zip it up this will shut up the noise by closing the split and keeping it like that. It did not cause the check engine light to illuminate and no performance was lost so this should do the trick. To replace the hose with a new one will be a PITA to get in there without removing things. Thanks for all the advice i appreciate it.

 

That is your PCV system. Probably has never been serviced. It will cause a lot of problems with leaks and blow seals if not taken care of ASAP.

https://volvoforums.com/forum/volvo-...ginners-18639/