noise

Hi,
In the last few days my 2014 cascadia developed a noise. It sounds like tires when you roll the window down but much louder. It starts at 55 mph and gets weaker faster i go. I can hear it more when with a trailer or under load. More likely coming from the back but not sure. When cruising and giving it more gas the noise gets louder. Moment i get my foot off the pedal it gets weaker. Under 55 i barely notice it. Truck has 400k miles on it and i am pulling tanker. Any ideas please. Thanks

 

this makes no sense, please re-read..

1) It sounds like tires when you roll the window down but much louder. It starts at 55 mph and gets weaker faster i go.

2) When cruising and giving it more gas the noise gets louder.

you first say it gets weaker the faster you go, then you say it gets louder the faster you go....can't have it both ways.

 

Lets say i go 60 on flat. The moment i press gas and create more torque it gets louder. Its louder under torque

 

My best guess would be turbocharger.

 

Any vibrations, rattling or humming?

 

Forgive me if this seems like a stupid question, but it has to be asked. Is your engine fan stuck on?

 

Or exhaust/flex pipe leak.

 

Yes, before this noise started i had vibrations once in a while and only with some tandem trailers and only between 34-50 mph! I thought this was the trailer problem. This noise that i hear is a humming noise. Low frequency hum

 

Engine fan starts and stops like it normally does

 

So i shut engine off while driving and noise is still there. But its so weak that i am not sure. There is tires hum and something else on the background.