Hissing

[snarkee]

mine too, its rpm and load sensitive.

 

hopefully tomorrow it will be a tad warmer so I can look at it

[snarkee]

cant seem to find anything........i did notice after i shut off the truck and removed the key, i had a slight static sound for 30 seconds.....the radio and lights were off...it sounded like it was coming from the dash area and not the onstar speaker/aspirator whatever its called

[toothpick]

I don't have Z package and can, when it decides to make the noise, hear it in park, just pressing the accelerator even so slightly. With a load, it becomes more like a muffled exhaust sound, like old school exhaust manifolds used to sound.

[Snow White]

cant seem to find anything........i did notice after i shut off the truck and removed the key, i had a slight static sound for 30 seconds.....the radio and lights were off...it sounded like it was coming from the dash area and not the onstar speaker/aspirator whatever its called

 

maybe a different sound? the fan blower is always on so when you shut the truck off the fan blower is still spinning... fyi.

[Slabi]

Any chance it's a vacuum leak from the power brake booster...try pumping the brakes with the engine running and see if the sound changes. ??

[toothpick]

The frustrating issue is that the particular sound is that it sounds differently at different times. I'm attempting to make a log of conditions together, then present them to the dealership for review when I bring the truck in for a look over. I figured it would be worth it for at least a documentation point of view that I brought it in to them to check out, even if they say they can't find anything. If something goes wrong down the road, it just helps my position to have tried.

 

If I place the truck in park and barely press the accelerator pedal, the noise will surface briefly, then disappear. But then during a given acceleration range, under different loads, the noise gets louder, but stays persistent through some acceleration. It disappears not immediately after releasing the accelerator pedal, I'd say after the RPMs lower to a given range.

 

Very frustrating.

[snarkee]

Any chance it's a vacuum leak from the power brake booster...try pumping the brakes with the engine running and see if the sound changes. ??

 

 

nope

[snarkee]

The frustrating issue is that the particular sound is that it sounds differently at different times. I'm attempting to make a log of conditions together, then present them to the dealership for review when I bring the truck in for a look over. I figured it would be worth it for at least a documentation point of view that I brought it in to them to check out, even if they say they can't find anything. If something goes wrong down the road, it just helps my position to have tried.

 

If I place the truck in park and barely press the accelerator pedal, the noise will surface briefly, then disappear. But then during a given acceleration range, under different loads, the noise gets louder, but stays persistent through some acceleration. It disappears not immediately after releasing the accelerator pedal, I'd say after the RPMs lower to a given range.

 

Very frustrating.

 

 

verrrrry inconsitent. thats why i havent taken it in to the dealer

[L29er]

I don`t have this issue. Very strange, just as strange as mine not starting when its cold.

 

Hope they get it fixed for you Mark. Its been much to warm here for my dealer to troubleshoot mine.

[98 Z71 SLT]

You guys are describing an exhaust leak. A very small leak.

 

Re-torque your driver side manifold bolts

 

Re-torque y-pipe bolts

[pm26]

Hmm, I had an exhaust manifold gasket leak on my '95 Nissan V6 pickup and it was only noticeable when the engine was cold on acceleration. After the engine warmed up, the gaskets sealed better and the rumbling noise disappeared. This was a very common issue on Nissan 3.0 V6 engines on pickups, Pathfinder, Xterra and Quest minivan.Virtually every one developed these leaks after about 80k miles. The good thing about that was that the techs could identify the problem instantly and it was easy to fix.

[snarkee]

You guys are describing an exhaust leak. A very small leak.

 

Re-torque your driver side manifold bolts

 

Re-torque y-pipe bolts

 

funny you say that......cause today when i left for work at 530am, I had a "tick" which souned to me like an exhaust manifold leak

[bud4ya]

Any update on the whinning noise? My 08 Denali is doing the same thing. I am going to try to get it into the dealer next week and have them look. It just makes like a s/c whine under acceleration.

 

You guys are describing an exhaust leak. A very small leak.

 

Re-torque your driver side manifold bolts

 

Re-torque y-pipe bolts

 

funny you say that......cause today when i left for work at 530am, I had a "tick" which souned to me like an exhaust manifold leak

 

[oldmann]

FYI...warmer out today and my truck is not hissing.

[bud4ya]

I will do the same test mid week when it warms up here and see if my hissing goes away. Probably Wed or Thr suposed to be around 50

 

FYI...warmer out today and my truck is not hissing.