HISSING BUZZ SOUND - Please Help!

awilley17 · December 8, 2015

Hello fellow GM truck owners,

Really need some assistance/advice. I'm reposting this because I had only one response and I can't find any other threads that fit my issue.

I own a 2015 Silverado 4.3 L with 7000 miles. Two months ago I noticed a minor hissing/buzzing sound coming from behind the dash and or underneath the steering column. The sound is a bit hard to describe, but I would compare it the sound of large volumes of sand being "dumped" that grainy sliding sand sound. I know its a weird description but the best example I could think of.

Only happens when the car is put under stress such as accelerating quickly, driving up hills, and its pretty steady when the vehicle is going 70MPH or higher. Also only starts up after the car has been driving for at least twenty minutes.

When I am cruising on the highway in the fast lane going about 75-80 MPH the constant hissing is VERY ANNOYING and is always present. It ruins the quiet cabin

It BOTHERS me, and I've brought it to the dealership that I bought the truck at twice. First time they didn't hear it. Second time I did a ride along and he noticed it. Came back and they told me it was just a normal "engine noise".

Took it to a second dealership for a THIRD time. Did a ride along guy told me a bunch of technical jargon but what I got was is that it was the sound of the engine exhaust.

Is it just me. This issue is driving me CRAZY.

Appreciate any responses, I'm minor OCD and this sound has been ruining my brand new purchase!

The Zip · December 8, 2015

You may want to capture the sound and someone may be able to assist. Guessing the dealer did this, but check to see if your duct work is not defective or securely fastened near and around the air filter.

awilley17 · December 8, 2015

I'm assuming that the first dealership did this, but they didn't mention that they did. They said they checked my firewall which covers checking my duct work I'm guessing.

The Zip · December 8, 2015

The dealer may have been checking your sound deadening on the cabin side of the firewall, but if it was faulty reparing it would not have stopped the sound, only eliminated you from hearing it. Have the dealer look at the duct work and fasteners around the engine air filter. Also, other owners can verify if this is normal or not.

awilley17 · December 9, 2015

Ill keep this in mind. Do you think this may be the issue considering that the sound is associated with engine workload?

The Zip · December 9, 2015

The hiss will probably get louder under throttle, but just pop the hood and take a quick look around the air filter, something could just be loose.

pm26 · December 9, 2015

The hiss will probably get louder under throttle, but just pop the hood and take a quick look around the air filter, something could just be loose.

Like GM quality control, for example?

awilley17 · December 13, 2015

I'll have to ask them to look at it. I've popped the hood and looked around but I don't see anything that seems out of the ordinary. Just hate taking my truck to the dealership for a 4th time. It's getting ridiculous.

awilley17 · December 13, 2015

UPDATE:

Just drove my Silverado about 30 miles south on the freeway. Minimal sound, faint but I could hear it obviously since i'm looking for it. On the way BACK the sound was MUCH MORE pronounced.. I mean it was bad enough to where I recorded the sound on my iphone while driving (I know, I know, sorry). The sound was a very pronounced buzzing/hissing. When I got off my exit at the stop light I put the truck in park and hit the accelerator.. sound came back. So it does appear when the vehicle is not moving and the RPM's are revving. The sound only makes its appearance when you press on the accelerator, if I'm going 80, then left my foot off and slowly cruise down the sound disappears.

Came home and inspected the underside of the car, and the engine bay above. Couldn't find anything out of the ordinary. Taking it to the dealership first chance I get. Am I really the only one out here experiencing these issues? Seems hard to believe. Just my luck.

pm26 · December 13, 2015

In case you did not know, GM800 series trucks had gurgling and hissing A/C noises behind the dash occasionally and that was considered normal for the system. I am not sure if newer trucks exhibit the same symptoms, but if it is just related to A/C operation, i would not lose my sleep over it.

awilley17 · December 13, 2015

It does resemble a gurgling/hissing. I wondered if it was my AC. It's just the gradual increase in sound that bothers me, and the sound itself is somewhat loud and it ruins the experience for me cause I can't stop noticing it. Also this may be a dumb question but when I'm not running my AC unit would it still make that noise?

pm26 · December 14, 2015

It does resemble a gurgling/hissing. I wondered if it was my AC. It's just the gradual increase in sound that bothers me, and the sound itself is somewhat loud and it ruins the experience for me cause I can't stop noticing it. Also this may be a dumb question but when I'm not running my AC unit would it still make that noise?

If the A/C is off and the noise was caused by the A/C operation, then obviously no.

awilley17 · December 14, 2015

Once I get my truck fixed from my recent collision I'm taking it back to the dealership. For the 4th time. Going to have them look at both sides of the firewall and look at my air filters. So sick of this shit. Really starting to think I should have gone with dodge or ford.. This belief will be solidified if they come back and can't find anything. Whenever I hear the sound while driving it makes me want to punch something in the face hard.