Ford Diesel and Choooo sound.

[FADEC]

Was behind a newer Ford diesel truck yesterday, that made a weird sound. Every time the driver accelerated and the truck shifted it would let out a loud CHOOOO sound. It would also make this sound if the driver accelerated then lifted off the accelerator.

It seemed like it was coming out of the exhaust or from underneath the truck. Truck looked stock and had a quiet exhaust. Driven by an older man. Also saw a different Ford diesel later that day that made the same sound. Have not noticed this sound from Ram or GM diesel's.

Is this sound from some exhaust component that is breaking down? Or something with the new DEF fluid. It's a very odd sound to be coming from a truck. Very high pitched.

 

[jeepman3071]

Likely some kind of exhaust leak somewhere or issue with the turbo.

 

[Smokescreen]

I have heard that lots from Ford diesels. There are simple mods they do to make the turbo sound louder by taking off parts or venting parts (wastegate) to atmosphere. I have heard both the choo sound and the amplified whistle and even a heavy sound like compressed air.

 

[Linctex]

Originally Posted by jeepman3071
Likely some kind of exhaust leak somewhere or issue with the turbo.


Wrong.

These turbos have "variable Vane" technology.

At low RPM's the vanes are laid down flat, almost closed - this is so the angle of the exhaust stream hits the blades of the turbine to get it to spool up faster.
These narrow vane openings makes the whooshing sound.

Under heavy loads, the vanes go wide open.

 

[Linctex]

Here's a good picture explaining the concept:

 

[DoubleWasp]

All it takes is a cold air intake.

The factory PSD turbos either whistle like a tea kettle or chuff like like a blowoff valve with the intake or exhaust even mildy uncorked.

6.0 is the chuffer, 6.4 is the Whistler.

The 6.0 even makes noises just shutting the engine off. ZeeeewzewzewzewHUUUFF!

For whatever reason, Cummins and DMax turbos have little tell tale.

 

[FADEC]

Originally Posted by DoubleWasp
All it takes is a cold air intake.

The factory PSD turbos either whistle like a tea kettle or chuff like like a blowoff valve with the intake or exhaust even mildy uncorked.

6.0 is the chuffer, 6.4 is the Whistler.

The 6.0 even makes noises just shutting the engine off. ZeeeewzewzewzewHUUUFF!

For whatever reason, Cummins and DMax turbos have little tell tale.

Definitely a high pitched whistle more like a chhooooo sound. Seems like it came from the rear of truck. Must have been the 6.4