What is This Whistling Noise?

[SkiDooNick700]

Hello all. I've noticed this whistling sound at idle on my truck. I am unsure how long it has been making it.

 

In the video, I start it up, give it a couple very light Revs to see if there is any difference in sound. Then, I cycle to R, N, D, N, R, P. The audio turned out OK, you can hear the whistling sound the best at 25seconds and thru the end.. I don't know if it makes the sound as I am driving down the road.

 

EDIT: You can't really hear the sound when looking at the engine bay. It is most audible when under the truck.

 

Any thoughts on this? I am probably going to swing by the dealer after work tomorrow and have them take a listen.

 

I appreciate your responses. Thanks!!

 

 

[gone_fishing]

Flapper valve maybe? Check this TechLink report out: http://sandyblogs.com/techlink/?p=3296

[SkiDooNick700]

Flapper valve maybe? Check this TechLink report out: http://sandyblogs.com/techlink/?p=3296

 

Interesting, maybe I'll have to give that a try just to see what happens.

[Jordan18]

I would bet money on it being the flapper but I haven't really paid attention to exhaust noises on mine, I have the GM borla exhaust.. I'll listen underneath and see if I can find a similar noise when I have time today

[SkiDooNick700]

Couple guys from the dealer looked at it. They are saying it's normal and just the sound of the oiL being pressurized and pumped thru the orifice. They kept telling me I had a really good ear to hear it.

 

I'm gonna mess with the flapper tomorrow just out of curiousity.

[TedzGMC]

Its the secret turbo. You didnt know we had them?

[SkiDooNick700]

Lol that would be the dream.

[20L8TSierra24]

Its the little weep hole in the rear of the mufler to let condensation out. I clamped my flapper open and the whistle went away as well

[tanner709]

Anyone have the TSB number for this job? My dealership is giving a bit of resistance and saying its normal operation seeing as I have nothing to reference.