Squealing noise silverado 2014 when she is shut down

[Rush78]

I have a 2014 1500 silverado 5.3. When the truck is off there was been a squealing noise coming from under the hood, it's there for a long time after too. Say 5 hours later or more. It will make the noise and stop then do it again. Kind of reminds me of the old dial up modems. I have never heard it in any of my older trucks and have no idea what it is. My truck is about a year old and has less then 12000 on it. Was wondering if this is normal with the new models and what it is. The first time i ever heard it was right after the annual inspection. I took her home and gave her a wash and wax. Never thought much of it at the time because i had just gotten her back and figured if it was something wrong that they would have picked up on it. Any help would be appreciated, even to kill my own curiosity now.

[Jsdirt]

If it was leaking enough to make that sound, I'd bet the A/C would be non-op by now. Certainly possible though - could be a leaky high pressure blowoff valve.

 

A mechanic that's been around A/C will instantly pick up on the smell too - I would think the previous dealer that looked at it would have. It has a distinct smell to it from the oil when there's a large leak. If not, a refrigerant detector would definitely pick it up. There would also be a big oil spot wherever it was leaking from - dirt will stick to it, making it pretty obvious, especially on a truck that new.

[Jsdirt]

Battery disconnected eliminates an electrical cause. Has to be pressure venting from EVAP. I have no idea where those components are located on the new ones.

[Rush78]

I have gotten an answer from Hickman motors which actually makes a lot of sense to me.

The video has gotten around the rest of the garage and was seen by one of there mechanics who has the exact problem. He has traced the noise and found it coming from a relief valve belonging to the evap system, which is located under the hood in that area. The fuel system in the new trucks is a fully inclosed pressurized system, everyone knows what happens to gas in a cherry can left in the heat, the valve allows this pressure to vent. Which explains why the first time I heard it was when I gotten the truck back.

That day was the first extremely hot day we actually had for the summer(I live in Newfoundland, Canada). I had just filled the truck up and was washing/waxing it before we left to go camping. I also live in a very quiet neighborhood which makes it the perfect time and place to hear it. After thinking back all the times i heard the noise the temperature and quite had played a key roles. Even with the latest time where the temperature and humidity were high.

So the truck is actually doing what it is supposed to do. Plus the sound When you think about it and listen to it again actually sounds like a small toy train whistle. It happens later after the truck has been sitting for a while because the pressure is relived normally with the engine running and and gas flowing. While she sits the pressure builds.

Not sure if I explained it good enough for anyone to make any sense out of it. But we got talking about it with the Hickman motors guys and it made plenty to me and them.

I also checked my battery, which is all good, and disconnected it to see if it helps.

I got another full tank of fuel today so all i need now is a hot day. Which doesn't look good anytime this week....lol

The video is still being sent to GM from what I have been told.

[Rush78]

Was talking to the guys at the dealership apparently I not the only one who has this problem, but the first to have it on video. They are all stumped, everyone including the mechanics after i Showed them the video. They asked me to email it to them but it was to big a file and i never had my usb for the phone. So i gave them the link them the link. The head of service has taken everything and looking into. Asked about leaving the truck but like i figured, it makes no sense because you can't tell when it's going to happen.

[The Zip]

Deleted, kinda missed the part where the truck was OFF.

[The Zip]

Start with the Hickam Motors service invoice, whatever they did had a negative impact on the component making the noise. If Hickam is a dealership, they should have conducted Goodwrench multipoint inspection. Find out from them what that inspection entails. Went to the dealership yesterday for truck maintenance and wanted to hear the 2016 SS while I was there, the battery was dead. So don't assume the battery is good based on the age of the truck.

 

If this was me I would disconnect the battery for 10 minutes or so and see if everything resets. If it was still making the sound, the battery would still be on the hook. I would take the battery in to check the volts, recharge if low, then see if it will hold the charge. An auto parts store could tell you volts, low, and if the battery can hold a charge. The issue should have the dealership stumped, but whatever it is needs juice from the battery or else it wouldn't be making that sound? Ask the service department what are they going to do and if you decide take the truck in, I would tell them to look at the battery first or else you run the risk of them disassembling parts.

 

Anything that goes wrong with my truck and I don't know exactly what it is, I usually start with the easiest to get to and the cheapest component in the link. In your case the battery would be a no-brainer for me.

[Rush78]

Lol...no worries. I can't explain it, but I do have a video with the noise and the truck isn't running. It was sitting up roughly 5 hours when i noticed it this time. I was wondering if maybe it could be the computer board or something. Wish i could post the video.

[Rush78]

Never mind won't download

[Jsdirt]

Take the battery out of the equation, and I bet the sound goes away. Whether it's low or fully charged probably isn't going to matter - something has failed or is failing ... or is just poorly manufactured, as was the case with my singing transformer.

 

In my case the transformer worked, but emitted a continuous tone almost identical to the sound this truck is making. Made in China ...

 

I had the dead battery issue with my '07 when it was new. No explanation was given as to why it totally died in less than 12 hours, on 3 separate occasions. I blame the electronics. With Onstar and everything, whose to say that some unethical individual couldn't trigger a battery drain remotely, in order to drum up dealership business? Anyway, the dealer tweaked the computer under warranty to output a bit more, and I didn't have an issue until years later. After towing my stuck ATV with plow out of the snow, the wife parked it in the garage. I went out the next day, and it was dead. None of the light switches were in the on position when I checked. Another mystery. Still ended up getting 8 years out of that battery, and sold on Craigslist for $40. Probably would've gone a couple years longer if not for the rogue electronics in this thing ...

 

 

A battery that new ('14) could easily be restored to like new condition with a 3-stage temperature-sensing charger, or any decent charger for that matter, if it was dead or just low.

[Jsdirt]

Yeah I can never get vids to work on this site either - I have to upload then link them to Photobucket.

 

Guaranteed it's probably something electronic doing this. Nothing mechanical would, with the engine off. I've heard laminates in a transformer make a similar sound when stepping down 120v to 6v, or 12v, or whatever the transformer was. Doubt there's anything like that in the truck, aside from the ignition coils. Could be stray voltage bypassing the switch, or shorting to one or more of the coils?

 

I'm really reaching here - could be anything, really ...

[Rush78]

I know a lot to take into consideration. Like I just got her inspected. Plus there's no issues with the truck other than the noise, and i am not around to listen to it long enough to get on my nerves. .lol.

 

Here is the video

 

Watch "Squealing noise silverado" on YouTube

 

 

see if this works

[Jsdirt]

That EVAP system is supposed to keep the fumes in the tank, so by design it shouldn't be venting pressure to the air at all. It's supposed to draw it in the engine on start up - the computer controls the little valves that send it to the intake. If you have a leak like that, it usually throws the light on. Makes sense that pressure venting would make that sound - I've heard a SLA battery do that when a failed regulator sent out 19-21 volts. Cooked the thing alive. Could smell rotten eggs and hear the whistle of the saftey valve venting pressure.

 

Stupid EVAP system shouldn't be in vehicles to begin with, but that's another topic for another day!

 

It's the most ingeniously engineered system for vacuuming hundreds of dollars out of your wallet. I think it was designed solely for that purpose ...

[The Zip]

Take the battery out of the equation, ....... - something has failed or is failing ... or is just poorly manufactured, .....

 

To tell you the truth, if my truck wasn't making that sound before I took it to Hickam, I'll be thinking what the heck did they do. I agree with the above comment but I would keep the battery in the equation.

[Rush78]

The car charcoal canister was what my captain was telling me about on the old rigs. On my 07 Silverado the evap code was always coming on. Got to the point where i didn't care about the engine ligjt as long as the truck still ran and it was blinking....Lol as the old saying went around here Ford was always found on road dead and the chev kept going but was lighting up like a Xmas tree.

[The Zip]

Ran into a mechanic there today who told me two things I can try the next time I hear the noise. 1) take off the gas tank fill cover, if it stops there could be a problem with the evap system. 2) take off the oil cover, if this stops it then it's the PVC valve.

Both of these would have something to do with venting, good recommendation, give it a shot

 

 

Can't be the PCV. Once you shut the engine down, the vacuum or pressure there stops.

With normal operating components I would agree, but Rush has some component that has failed or is failing and the pressure is not venting correctly.