Annoying Squeak every time cylinders reactivate from V4 to V8

[Z71Texan]

At 1800 miles I noticed that my truck started or has been making this really annoying, high pitched squeak every time it switches from V4 to V8 on the highway. It almost sounds like a valve opens up when the cylinders reactivate and is driving me nuts!! I don't hear anything when it goes from V8 to V4. Unfortunately, I don't get to enjoy the "quiet cabin" GM advertised because of the squeaking.

 

Has anyone else experienced this issue? I have the 5.3L V8 in a 2015 LT Crew Cab short box Z71

[Fishingbear]

I have this same problem on my 2015 1500 Sierra Crew Cab SLT 5.3L short box. It sounds like two pieces of metal hitting each other every time I hit the gas when it it in V4 mode and shifts to V8 mode. I plan on taking it in soon to have it looked at. I've read on this forum that it has something to do with the exhaust system and a flapper valve. I'll post an update after I take it in a few weeks from now.

[gmtech117]

It's the valve that opens up in the exhaust. Mine did the same thing, I put a bolt in it to keep it open at all times. The valve is only to cut down on drone when in v4 mode, not much of a difference when always open. If you take it to the dealer the fix is to replace the exhaust system, if you search it looks like a lot of people have had it replaced, only for it to start squeaking again later on.

[Fishingbear]

I just got my truck back from the dealer and was first told that they "could not duplicate the problem". This was after they put 25+ miles on the truck. I then took the service manager for a ride and we both heard it right away. He then proceeded to tell me that it's "a normal operating characteristic of the vehicle" and that there is no fix. He also mentioned that there is a fix for the 2014's with the exact same problem but that GM has not issued a fix for the 2015's. He suggested I turn up the radio so I wouldn't hear it.

[SILVER SLED]

Have him show you the bulletin where it's normal. There is a bulletin for the 14's, just because it hasn't inclueded the 15's yet doesn't mean they can't replace the exhaust/fix the 15's.

[Z71Texan]

I just got my truck back from the dealer and was first told that they "could not duplicate the problem". This was after they put 25+ miles on the truck. I then took the service manager for a ride and we both heard it right away. He then proceeded to tell me that it's "a normal operating characteristic of the vehicle" and that there is no fix. He also mentioned that there is a fix for the 2014's with the exact same problem but that GM has not issued a fix for the 2015's. He suggested I turn up the radio so I wouldn't hear it.

Im sorry to hear that. I took mine to the dealer last month and the tech drove and I rode with him and he heard the squeak and within 5 miles he was sure it was reproducible and we could hear it from the back right side of the truck from the same butterfly valve in the exhaust. The tech read several bulletins for a couple hours and ended up ordering a new exhaust for the truck. It came in over the holidays and was installed the first week of this month and so far so good. No more squeaks =)

[Fishingbear]

Im sorry to hear that. I took mine to the dealer last month and the tech drove and I rode with him and he heard the squeak and within 5 miles he was sure it was reproducible and we could hear it from the back right side of the truck from the same butterfly valve in the exhaust. The tech read several bulletins for a couple hours and ended up ordering a new exhaust for the truck. It came in over the holidays and was installed the first week of this month and so far so good. No more squeaks =)

 

So it sounds like your dealer replaced your exhaust because of the chirp and mine told me it was normal... and we both have 2015's. This is frustrating! I guess I better take it to another dealer for a second opinion. Please let me know if the noise comes back. Mine is so obvious and loud that I hear it EVERY time my engine goes from V4 to V8.

[ChadOD]

I also have a 2015 Silverado Lt1 5.3 sounds like a cricket chirping or sometimes it keeps going for like 10 seconds. I've seen posts here both claiming the 4wd switching in auto and the exhaust flapper valve. Z71 Texan you're saying the new exhaust solved the issue?

[Sierra Matt]

I am also having this problem. The dealer says that some do it and some don't, and that its operating as designed and since GM has not come out with anything on it there is nothing he can do. First new truck in 15 years, but I'm getting tired of the same response to everything.

[holty]

I just traded my '14 5.3L in and it had the chirp EVERY SINGLE TIME it went from V4 to V8 mode. Drove me bat shit crazy!

 

My new 2016 Denali does not (yet) make the noise.

[Tneely]

My truck 2016 gmc sierra is squeaking something fierce. Bought it brand new... From what I've been told it's a flap valve in the exhaust system. Dealer or G.M. still haven't fixed the problem. Nothing but the run around and lip service!

My truck 2016 gmc sierra is squeaking something fierce. Bought it brand new... From what I've been told it's a flap valve in the exhaust system. Dealer or G.M. still haven't fixed the problem. Nothing but the run around and lip service!

[GMCustomerService]

Good afternoon Tneely,

 

We understand how this noise can be frustrating and assure you this is not the kind of experience we want you to have in your new truck. Please feel free to send us a private message if you'd like to discuss further, we’d be more than happy to assist. Hope to hear from you soon!

 

Best,

 

Bret B.

GM Customer Care

[sk]

This is a known issue and is DEFINITELY the PEV (Passive Exhaust Valve). I don't have the PI number available but tell your dealer to check the TechLink bulletin from June 2014. Here is a cut-and-paste from the pertinent part of the TechLink (there are actual pictures in the online article):

The second noise condition is a whistle noise heard coming from the muffler area of the exhaust system. To diagnose this condition, temporarily lock the Passive Exhaust Valve (PEV) in the open position.

Equipped on all light-duty trucks, the Passive Exhaust Valve, located behind the muffler, acts as a broadband tuner in both V4 (Active Fuel Management) and V8 mode for a more refined sound.

Rotate the Passive Exhaust Valve counterclockwise. For testing purposes only, install a 1/4" x 20 x 2” steel bolt, nut, lock washer and two large standard 1/4" x 1” outside diameter washers (body washer) in the Passive Exhaust Valve.

If the condition is reduced or changes greatly in severity with the bolt installed, replace the exhaust system.

The vibration condition may be noticed in the seat or steering wheel when the truck engages V4 mode (Active Fuel Management). After verifying the condition, check the exhaust system for Ground Outs at the mounts and repair as necessary. For testing purposes only, install the bolt, washers and nut as described above. If the condition is reduced or changes greatly in severity, replace the exhaust system.

 

 

My dealer and I have been monitoring mine for a few months. As said above right now the only fix is to install new exhaust from the muffler back and the same style valve is still installed so many begin to squeak again in a few months.

 

 

 

[BigBlueLB756]

http://sandyblogs.com/techlink/?p=3296

[RonK99]

Fixed my 2015 Seirra flapper from 4-8 SQUEAK with FLUID FILM

After 2 applications NO MORE SQUEAK

and it doesn't burn off either!  I drive 120kms on the highway return from work still QUIET!   

https://www.canadiantire.ca/en/pdp/fluid-film-rust-corrosion-prevention-0381567p.html

Edited September 9, 2020 by RonK99