Can’t figure out this noise!

2012 Volvo S60 2.5

noise only happens when cold. Goes away after the 15 seconds. Noise gets loud when you first accelerate for a mile or so. Then it goes away completely until it’s cooled off for a hour.

 

I'm assuming the noise is coming from the engine and not inside the cabin? When the car is first started, have you tried to pinpoint the location of the noise? Why not record and upload it to YouTube. That would help us to help you.

 

sounds like it could be an exhaust leak that goes away once the metal heats up and expands sealing the leak. Only other thing I can think of is that on some models there's a vacuum pump that kicks on with a cold start to build up brake booster pressure. I'd open the hood and give a listen - it should be on the drivers side by the firewall and will not change sound with acceleration.