For the last couple weeks my Tahoe has been making this very odd fluttering whistle like noise. You can hear is on start up and it soon fades. But... As I start driving and acceleration under load its back. A Fluttering, whistle-esque like continuous noise. I have a video although it doesn't do this noise justice. I'll upload it as soon as I figure out It sounds like its coming from back of the motor. Under the truck whilst it is being rev'ed sound frightening to say the least.

 

https://www.youtube.com/watch?v=cW89...ature=youtu.be

 

Have you checked for exhaust leaks around the headers?

Not sure if I am hearing exactly what your describing. It almost sounds like a bad lifter that's not pumping up.

 

I made sure everything was tight. Header bolts, band clamps, o2's. Nothing else past that. Also checked under the valve cover. everything seems to be running smooth. The sound is coming from below the headers. bottom- rear of the engine.

 

Sounds like an alternator, can hear a lifter noise, but something definitely goin on with alternator or one of the pulleys hard to tell from video though!! How is your battery?? My alternator made similar noise when my battery was goin out...

 

Possibly around the torque converter/flex-plate area?

Maybe the bolts are coming loose or the flex-plate is cracked.

 

Wouldnt that be more of a knock than a whistle??

 

Possible starter not pulling all the way back in???

 

Only my couch pulls out, I don't...

 

Some have heard a knocking while others say there is a buzzing.

It's all crap to me until I start poking around and listening to different area's.

Bad cam bearings can sequel as well as when the lifer roller seizes up.


Now that I listen again it sounds like the power steering pump is whining.