[utahpaul]

Bought a new 2023 Avenir for my wife as a birthday gift yesterday. drove it home from out of state so 400 miles from new. The car's chassis under the front seat mounting bolts right and left make a constant creaking like noise at any speed over 60 + mph and only gets worse as speed increases. Also the push button start switch cover fell off into my hand after the 6th start when the photo was taken here at Navajo bridge AZ, looks like the pins were not pushed down during the switch assembly. We love the looks of the car ( sapphire blue with whisper beige leather ) but we shall see after I take this into our local Buick dealership service to find out what is going on here.

 

[utahpaul]

So here's the update....the start stop button was indeed broken and replaced, and after two days and many Buick Dealer Service "Tech" personnel taking our new 2023 Avenir for a ride at speeds over 70 - 85 mph to try to hear the same creaking / rattle noise?, they heard it, and they found it, the noise comes from two splash pans, located directly below the right and left front seats, they measure 24" x 36", and when tapped from below on a lift, make the same noise. These pans are thin plastic, and at those freeway speeds cause them to vibrate. And it's because there is not any sound deadening material at all under the car or on these plastic panels to absorb the vibration. They even found the same issue on any FWD Envisions ( they claim the AWD do not have these panels ) on their new car lot. So did they "offer" to correct it? Nope, they said "you can remove the panels and it will work just fine" , ah No, not going to happen, So I called Buick cares, and they documented the Noise issue,as well as the knucklehead service advise. Then my wife and I put the Buick on a lift at home, removed the plastic panels, and used aluminum backed sound deadening material to cover the underside mounting points and some of the center and end areas on this panel, both left and right. Put our car back together and guess what?, No More Noise at any speed up to 95 mph ( that's as fast as I cared to go on our highway for the noise test ). Hope this helps, but and as to Buick helping, Nothing

 

[utahpaul]

The deadening material is called "Resisto" # 66876, at Home Depot, $14.99 for a 6" x 25' roll ( the product shown below is a 6" x 75' roll, you only need the 6" x 25' as we still had a 1/4 roll left over after the job was finished )....the panel needs to be removed of course, and cleaned of any dust or dirt where your placing the sound deadening tape....I restore old cars and have used this stuff, as well as "Tite seal" on many cars and trucks, mush cheaper than "dyno mat" and does the same thing IMO.

 

[utahpaul]

So here's a few photos of me doing the car....the first is the panel location, then after it's cleaned, you cut and place the sound deadening tape where you feel it will do the most good, I tapped on the panel while on the car, and got a idea where it was needed, I also added a few squares onto the underbelly of the car itself, just a few, where it sounded "tinny" to a tap of my fingers.....maybe over kill, but the noise is gone for good....but again, Buick service did nothing to correct this on my 500 mile new Avenir, and after two days at the dealer, they told me "hey, you can just take them off, and re-install if and when you sell the car"....

 

[utahpaul]

Here's another photo of the center of the Avenir, showing the exhaust and the right and left pan locations, and the right pan removed sitting upright before adding the sound deadening tape....and of course I also used a little bit of heat from my electric heat gun, just to make sure the tape sticks well ( no problem there, it sticks like crazy even without the heat as you'll find out if you decide to do this ).....again, the noise only happens after say 65 - 80 mph, super noticeable sitting in the rear seat, and listening to the area where the front seat bolts to the floor....same noise in all 2021 - 2023 FWD Envisions which have these same underbelly splash guard plates....so four plates total, two 24" x 36" left and right front, and two 24" x 20" in the rear....you'll also notice I added the silver deadening tape to the tops of the pans where they mount to the car, be sure to poke out the holes for the mounting studs to clear when you go to re-install these....that and do not block off any of the water drain holes made into the plastic pans. As to time, it took me 4 hours to complete, from rolling the car out, raising the car, getting tools, ( 10 mm deep socket, and one other very small socket for one small screw on each side ( I do not recall size ) heat gun, tin snips for cutting the tape, which works so much better than scissors, turning on the garage tunes, setting up a shop table to set the pans on, and just taking my time....and of course a "cold Tecate" after my wife and I took the car out for a test drive on the I 15 at up to 95 mph, Zero noise now, and the entire car is much more quiet.

 

[utahpaul]

Now that our brand new 2023 Buick Envision Avenir is quiet as to the "vibration rattle at speeds over 65 MPH upward"..... if Your Envision Factory Window Sticker, indicates "Buick Quiettuning with Active noise cancellation" as ours does, one has to ask, why did "WE" have to correct this?....just in case, dear reader, your not familiar with Buick's quiettuning? Here is the breakdown from Buick... https://www.sweeneybuickgmc.com/buick-quiet-tuning-noise-cancellation/

 

[utahpaul]

Hello all,

Found this info that may be helpful:
#23-NA-005 - Rattle or Flutter Noise Under the Vehicle at Highway Speeds - (Jan 31, 2023)

Go to repairprocedures.com
Enter vehicle: make/model/year and age set to ALL
Click on: APPLY ALL FILTERS

Use results to search for docs and more info.

I just tried this , it says I need to have a subscription.....anyway, I already shared our correction for this noise, it does work quite well.