Weird noise from under the hood

[foursixtysix]

Hey guys,
Over the past couple of weeks i have noticed a weird noise randomly coming from the engine compartment...At first I thought it was from the turbo but now I have noticed it whenever the fan is engaged. It usually occurrs after the accelorator is released and the engine rpm has dropped or is dropping. It's a steady high pitched tone that lasts only for a few seconds then goes away anyone have any ideas or had this problem before?

[Diesel Freak]

Possibly just a turbo fart!
Does it just happen after romping on the go peddle??
More like a flutter sound?

[Diesel Freak]

Mabe belt is slipping ever so slightly. try some belt dressing!?

[foursixtysix]

I don't think it's a turbo fart...I've heard that before, it's a weird steady tone maybe I can try to get a video of it, it's loud enough that I think the camera would pick it up

[sky120hunter]

I have had the same tone I think. I will try and describe what I am heaing. It almost sounds like a high pitch squeak. Lasts from 1 to 3 seconds. Comes and goes. Some days won't do it at all others every time you let up a bit on the throttle. Does not sound at all like a belt squeak! If you have been for a hearing test where you listen for the tones... it is like the one about one third of the way down from the highest tone. I had a tech look at it but of course it wouldn't reproduce on the test drive.

If you figure out what it is can you let me know.

John

[owtcast]

Sounds like you may have a leak on one of the intercooler hoses when the system is pressured up.