Cummins low pitch whistle sound

[Dbow20]

I am experiencing a low pitch hollow whistle that seems directly related to boost. It starts at 2 psi and fades out by 3.5-4 psi. It will make the sound rising through 2 psi as well as decreasing down through it. At first I thought a boost leak. I have checked for a leak and can’t find any. Also, would a boost leak fade out as pressure increases? The sound seems to be on the driver side but sound travels so it may not actually be on the driver side.
Has anyone else experienced anything like this?

 

[crash68]

At that low of boost I would guess probably some air flow resonance in the intake/turbo. Your probably barely touching the throttle your hearing the noise between 2-4 psi. Maybe the engine is taunting you to step on it.., it's saying "wusss"...LOL

 

[Dbow20]

You’re probably right! It’s a new sound after an intake modification so it might just be different air flow sounds I’m hearing.

 

[mtnrider]

.....It’s a new sound after an intake modification .....

^Your post should have started with this....

What kind of mod did you do? The stock system really is the best for flow and filtration unless you are heavily modded and pushing big HP so I personally wouldn't mess with it.


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[Dbow20]

The new mods include a s400 turbo on a 2nd gen manifold, pusher intake intercooler pipe and manifold, and pusher grid heater plate. So more than an intake mod

 

[mtnrider]

The new mods include a s400 turbo on a 2nd gen manifold, pusher intake intercooler pipe and manifold, and pusher grid heater plate. So more than an intake mod

I feel pretty confident in saying the source of the new sound is all the new parts you just put on it.


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[Dennis Shellito]

I realize you installed a new grid heater and gasket, but you could try using smoke around the grid heater to check for a boost leak. My truck had a leak at this gasket that other people could hear but I am too deaf and didn't hear whistle. The dealership tech didn't tighten the GH bolts which allowed the boost leak.

 

[crash68]

The new mods include a s400 turbo on a 2nd gen manifold, pusher intake intercooler pipe and manifold,

With those mods it definitely taunting you to step on it...LOL

 

[Dbow20]

I realize you installed a new grid heater and gasket, but you could try using smoke around the grid heater to check for a boost leak. My truck had a leak at this gasket that other people could hear but I am too deaf and didn't hear whistle. The dealership tech didn't tighten the GH bolts which allowed the boost leak.

I checked for leaks after putting everything together I used compressed air and soapy water and got all the leaks sealed up. At first I though boost leak but now I’m not sure since the sound goes away. You would think with a leak the sound would get louder with higher boost pressure.

 

[Dbow20]

With those mods it definitely taunting you to step on it...LOL

You’re not wrong. I have to baby it for now so I don’t create a few extra neutrals in my transmission

 

[Dbow20]

Here’s a video of the sound. It doesn’t come out very well in the video but around the 11 second mark you can hear it.

it’s easier to make out in this video

 

[Dbow20]

Has anyone else experienced a low pitch whistle like in the videos?

 

[Audiowriter]

It must be from the mods you made.

 

[Dbow20]

Still curious about the sound I’m hearing on my pickup. I know y’all have said must be from the new parts but I can’t find any other videos with the same sound.
I’ve noticed lately that the sound seems to be much louder and happens over a lager boost range when cold. When the coolant/oil warms up it is a little quieter.

-There’s no in and out play in the turbo shaft.
-no boost leaks
-exhaust manifold studs are all tight
-turbo mounting studs are tight

What else could be causing a low pitch whistle?

 

[Badger 13]

Is it possible that the "silencer ring" was removed from the inlet side of the turbo ??

 

[Dbow20]

Is it possible that the "silencer ring" was removed from the inlet side of the turbo ??

I didn’t remove it so it should still be there.
I don’t know what kind of silencer ring s400s have though so I don’t know what to look for.