2018 2500 Cummins hissing/air noise

[NUGNUG]

I have a 2018 2500 Cummins with only 17k miles on it. The other day, while waiting in line for fuel, a hissing sound started out of the blue coming from the engine bay somewhere. The truck has not thrown a code. It seems to only happen when the truck is at operating temperature, I do not hear it when I start it up cold. I checked the intake hose in the passenger fender to see if it had collapsed, and it had not. It was fine. The air intake hoses are all tight going from the air filter box to the turbo. I can't make it happen consistently. When it happens, it sounds like it is coming from the passenger floor area when sitting in the driver's seat. It's really odd. Any ideas on what to look for will be appreciated. TIA

 

[C M McCormick]

Exhaust Brake???

 

[NUGNUG]

Exhaust Brake???

It's not the normal exhaust brake sound I'm used to hearing when driving and slowing down. This noise it at idle as far as I can tell.

 

[C M McCormick]

It's not the normal exhaust brake sound I'm used to hearing when driving and slowing down. This noise it at idle as far as I can tell.

Yes I know that. But I have mine on all the time and at a stop light I can hear it. I'll turn it off then back on and there is a difference in sound. I came out of a 2nd gen and this is my first 4th gen. Believe me I'm still learning..
Craig

 

[NUGNUG]

I bought this truck new in 2018 and this is the first time my wife or I ever heard this noise. It's quite loud. If it's the exhaust brake, something broke in it. Thanks .

 

[AEdelheit]

I bought this truck new in 2018 and this is the first time my wife or I ever heard this noise. It's quite loud. If it's the exhaust brake, something broke in it. Thanks .

It could be an exhaust leak, when the exhaust brake turns on and builds backpressure any leaks pre turbo will make a hissing noise.

 

[NUGNUG]

It could be an exhaust leak, when the exhaust brake turns on and builds backpressure any leaks pre turbo will make a hissing noise.

Could this happen at idle?? Thanks

 

[Ozymandias]

Absolutely

 

[NUGNUG]

Thank you.

 

[kthaxton]

While this may or may not be relevant....exhaust leaks are sorta common. On mine, I would get a whistle only when using the exhaust brake and for the most part, was only audible with the window open and when I was nearly to a stop (likely because of less highway noise compared to using the brake at highway speed). I never noticed it at idle unless I was using the idle up feature with the EB on. I eventually noticed I could hear it (again, only when using EB) with the windows up as long as the stereo was off and I was listening for it.

I just recently fixed it over the Christmas break, replaced all exhaust manifold gaskets. It appeared cylinder #6 was the only one leaking and apparently #6 is the most common one to fail.

 

[NUGNUG]

Thanks kthaxton. I'll check that too.

 

[Wal_mart]

I had a hissing noise but on drivers side,The hydro boost liner hose was sucked up out of the hose.