Body Pop Noise coming from right rear on Sportback

[96americanluxury]

*Long post alert*

So for quite a while now, I have been experiencing a body pop type noise coming from the right rear of my 2020 FWD Essence Sportback. The noise sometimes occurred while accelerating, sometimes while braking and sometimes over bumps. But not every bump or even the same bumps, and not every acceleration or braking event. The noise was only present at speeds below about 45mph.

My Buick dealership replaced both rear knuckles in the hope that it was related to the lower link that causes a similar noise on the Chevy Malibu and Buick Lacrosse, TSB 18-NA-136. Unfortunately, this did not fix the noise.

I did a lot of diagnosis on my own and also with the technician. With the technician along, we would swap driving and riding in the back to get a better take on the noise and its location. We drove with the right rear door open and closed, the lift gate open, closed, or closed partially, removed interior panels including all rear interior panels and dropped the headliner, used an electronic stethoscope, and just about everything in between. We did find the noise was louder when the right rear door was open.

We eventually found a bump where we could replicate the noise each time, but only while moving forward and only when the right front wheel went over the bump first followed by the right rear wheel. Believe this is because the right front wheel flexed the body in a certain way to "reset" things and then when the right rear wheel went over the bump it flexed in a specific way to make the "pop".

We thought the noise may have been lift gate related (another user, @ready2fly, had a spot weld issue with his lift gate causing a similar noise). The technician actually got some very loud pops from the spot welds at the lift gate hinge locations on the body side by tightening the hinge nut. This, however, did not fix the noise.

A big break was when we discovered we could turn the noise on and off. By pulling on the right rear inner quarter panel brace when going over the bump, the noise would stop. Releasing pressure on this panel, and the noise would return. This was right inside of where the exterior C pillar trim appliqué lives.

After talking with multiple body shops about possible repair methods, we started by hammering each of the spot welds around this inner quarter panel area with a metal rod and hammer. This did not change or fix the noise.

During this, the technician suggested we look at the spot welds on the right rear door opening flange that the weather stripping attaches to.

There we found a spot where 4 panels (outer quarter panel, inner quarter panel brace and 2 others) meet and are spot welded together.

Using a metal dolly with a rubber cover to act as a backing plate against the outside painted portion of this flange, we hammered the spot welds on the inside at this location.

The noise was instantly gone after doing this, and it has now been 3 days of peace and solitude.

I have to give major props to my dealership and the technician for working so extensively and thoroughly with me on this.

I hope this may help anyone else who may be experiencing a similar noise that is driving them crazy.

 

[abizzle]

During this, the technician suggested we look at the spot welds on the right rear door opening flange that the weather stripping attaches to.

There we found a spot where 4 panels (outer quarter panel, inner quarter panel brace and 2 others) meet and are spot welded together.

Using a metal dolly with a rubber cover to act as a backing plate against the outside painted portion of this flange, we hammered the spot welds on the inside at this location.

The noise was instantly gone after doing this, and it has now been 3 days of peace and solitude.

I decided to look at the spot weld you mentioned and everything looked good. So I started pulling on panels and shaking the wheels to try and recreate the sound. About that time my hand hit the right rear taillight and there it was!

The right rear taillight is very loose. It seems like whatever fastener holds the right side in place is either loose, damaged, or missing. I haven’t tried to remove it yet.

I’m still not 100% sold on this being the problem, but it makes sense. The noise has been getting progressively worse, which coincides with a significant increase in opening/closing the hatch. I started doing Uber deliveries for Walmart in February and the hatch gets a lot of work.

Let me figure out how to fasten the light back down and I’ll report back.

 

[abizzle]

Reporting back…

So it wasn’t the taillight, but the taillight definitely needed to be fixed. It has two tabs on the outside edge and the tabs are supposed to slide into sockets. The opposite side of the taillight is held in place with a screw-on fastener.

Anyway… next step is to remove the fender liner, so I can access the top of the rear strut and check the mount. I’m hoping the problem is a gap that can be fixed by installing a washer. We’ll see.

 

[96americanluxury]

Reporting back…

So it wasn’t the taillight, but the taillight definitely needed to be fixed. It has two tabs on the outside edge and the tabs are supposed to slide into sockets. The opposite side of the taillight is held in place with a screw-on fastener.

Anyway… next step is to remove the fender liner, so I can access the top of the rear strut and check the mount. I’m hoping the problem is a gap that can be fixed by installing a washer. We’ll see.

Well that's a bummer it wasn't the taillight. Glad you got that fixed regardless though!

To your comment from your first post though about the spot weld looking OK, my spot weld looked OK as well.

There was nothing noticeably wrong or different about the spot welds compared to others.

But once we hammered on the welds, the noise went away.

So that may still be a possibility for your noise.

My noise was noticeably louder when the passenger rear door was open while driving to replicate the noise, which only made sense after finding out where the noise was coming from/those welds are located.

I never tried the rear strut mount, but did have the rear knuckles replaced, which did not fix my noise.

Hope this helps, and good luck. Keep us updated!

 

[abizzle]

Well that's a bummer it wasn't the taillight. Glad you got that fixed regardless though!

To your comment from your first post though about the spot weld looking OK, my spot weld looked OK as well.

There was nothing noticeably wrong or different about the spot welds compared to others.

But once we hammered on the welds, the noise went away.

So that may still be a possibility for your noise.

My noise was noticeably louder when the passenger rear door was open while driving to replicate the noise, which only made sense after finding out where the noise was coming from/those welds are located.

I never tried the rear strut mount, but did have the rear knuckles replaced, which did not fix my noise.

Hope this helps, and good luck. Keep us updated!

So far, I've noted five possible culprits from information posted on this and other forums. The knuckle seems to be the most widely reported solution, but I can't afford to replace them and realize they weren't the issue. Replacing both knuckles would cost around $160. Replacing both struts would cost around $260. Not to mention the heat index is currently around 115 degrees, so any project requiring more than an hour of labor will wipe me out.

Just the sound and the increase in frequency would seemingly point towards something being loose as opposed to worn out. I wouldn't be surprised if the fix turns out to be the addition of a washer or two between the strut mount and the strut. Could I be so lucky?

 

[Florida Sportback]

So far, I've noted five possible culprits from information posted on this and other forums. The knuckle seems to be the most widely reported solution, but I can't afford to replace them and realize they weren't the issue. Replacing both knuckles would cost around $160. Replacing both struts would cost around $260. Not to mention the heat index is currently around 115 degrees, so any project requiring more than an hour of labor will wipe me out.

Just the sound and the increase in frequency would seemingly point towards something being loose as opposed to worn out. I wouldn't be surprised if the fix turns out to be the addition of a washer or two between the strut mount and the strut. Could I be so lucky?

When I saw the opening description, I thought it was my problem on an '18 Sportback, 37K, 10 days left on warranty. Snapping noise at low or no speed when the suspension is moved after sitting for a minute or less. Dealer first couldn't find it. Waited two weeks until it got worse. They heard it and diagnosed as left rear shock/strut mount. The car is to have that replaced Monday. My position is that anybody with any automotive knowledge knows that you would not replace a key suspension part on on onlly one side of a 37K car. Both sides need to be replaced. They say they can't replace the other side if it's not defective. Service guy recommends calling GM customer service. In dialog with them, they say they rely on their dealers and do not override them. They work for contractors, not GM, and admit to having no automotive technical knowledge. I asked them what good are they if they are going to agree with the dealer with which I disagree. They just repeat their mantra. I'll let this run its course for a few more days, but any ideas about who in GM I can get to consider what, to me, is not even a close call.

 

[Tewks52]

When I saw the opening description, I thought it was my problem on an '18 Sportback, 37K, 10 days left on warranty. Snapping noise at low or no speed when the suspension is moved after sitting for a minute or less. Dealer first couldn't find it. Waited two weeks until it got worse. They heard it and diagnosed as left rear shock/strut mount. The car is to have that replaced Monday. My position is that anybody with any automotive knowledge knows that you would not replace a key suspension part on on onlly one side of a 37K car. Both sides need to be replaced. They say they can't replace the other side if it's not defective. Service guy recommends calling GM customer service. In dialog with them, they say they rely on their dealers and do not override them. They work for contractors, not GM, and admit to having no automotive technical knowledge. I asked them what good are they if they are going to agree with the dealer with which I disagree. They just repeat their mantra. I'll let this run its course for a few more days, but any ideas about who in GM I can get to consider what, to me, is not even a close call.

Any more updates if this fixed the clunking noise? I've read posts of possible solutions including loose suspension bolts, faulty weld spots in rear door frame area, worn rear wheel knuckles, washers on top of shocks. Seems sort of a shotgun solution approach. I appreciate all of the inputs just want to know which one to pursue. Thanks to all.

 

[abizzle]

Any more updates if this fixed the clunking noise? I've read posts of possible solutions including loose suspension bolts, faulty weld spots in rear door frame area, worn rear wheel knuckles, washers on top of shocks. Seems sort of a shotgun solution approach. I appreciate all of the inputs just want to know which one to pursue. Thanks to all.

I’m about to dig into mine and get it fixed. It’s really starting to get on my nerves. My first inclination is to check the strut mount on the LR. Just backing out of my carport on flat pavement is all it takes for it to start knocking.

 

[Tewks52]

I’m about to dig into mine and get it fixed. It’s really starting to get on my nerves. My first inclination is to check the strut mount on the LR. Just backing out of my carport on flat pavement is all it takes for it to start knocking.

I have been trying to diagnosis this problem and it appears it is definitely related to expansion of components related possibly to outside temperature. When the outside temperature is above 75 F the clunking noise is present on acceleration from start up to about 35 or 40 mph. I don't hear it at higher road speeds or on the interstate 65-70 MPH. Recently here in Ohio our heat wave (85-90F) ended and I immediately noticed at temperatures in the morning 60F or below the noise was gone. I've read on the 2017 LaCross there were issues with suspension bolts. I'm wondering if this could be what is happening on the Regal Sportback. As the temperature rises things loosen up (expand) enough to allow shifting in the suspension members which cause the clunking noise. The Tech Bulletin mentioned bolt torques of >66 ft lbs. Otherwise remove and replace the bolts with new bolts. Any thoughts?

 

[abizzle]

I have been trying to diagnosis this problem and it appears it is definitely related to expansion of components related possibly to outside temperature. When the outside temperature is above 75 F the clunking noise is present on acceleration from start up to about 35 or 40 mph. I don't hear it at higher road speeds or on the interstate 65-70 MPH. Recently here in Ohio our heat wave (85-90F) ended and I immediately noticed at temperatures in the morning 60F or below the noise was gone. I've read on the 2017 LaCross there were issues with suspension bolts. I'm wondering if this could be what is happening on the Regal Sportback. As the temperature rises things loosen up (expand) enough to allow shifting in the suspension members which cause the clunking noise. The Tech Bulletin mentioned bolt torques of >66 ft lbs. Otherwise remove and replace the bolts with new bolts. Any thoughts?

Well, I have a torque wrench, so I can check them. I live in SE Louisiana, so we stay above 60 degrees 9-10 months out of the year. The idea of expansion and contraction is valid. The sound of the clunking noise, to me, sounds like metal on metal. It has a slight "twang" that echoes briefly. The reason I believe it is suspension related is because I can push down on the rear bumper with a short, sharp thrust and trigger the noise every time. See if you can hear it when you push on the bumper.

 

[2RegalHouse]

Just wanted to add to this post as well - my wife and I each have a 2018 Regal Sportback - and the rear end popping has become increasingly prevalent on mine. The temperature does seem to have an impact as well as how long it has been sitting. If it has sat outdoors for a while or overnight, the first few turns backing out of my driveway or even the expansion joints in the driveway elicit the clunk or pop. I have also kept the list of:

1. rear knuckles - seems most often the cure - even if not long lasting for some people.
2. Rear coil spring insulator(s) (mine are intact and not damaged / overly compressed)
3. rear upper strut mount / spacer / washer - have not been able to inspect as have not yet removed the wheel well liner
4. body / inner quarter panel welds.

On the flip side - if its the bushing in the knuckle or even a bushing with the rear sway bar -- unless they fully deteriorate or start to have excessive play -- the thunk is rarely present during normal driving on the roadway. Its just the first initial motion or the first few initial seams in my drive, more noticeable in reverse. So I don't think I'm closer to ruining anything critical - its just annoying.

Rear knuckles will probably be my first item to try. We are both our of warranty so its my dime... I wish there was a way to lubricate the bushings and see if it helps.

 

[buckeyeguy15]

I

*Long post alert*

So for quite a while now, I have been experiencing a body pop type noise coming from the right rear of my 2020 FWD Essence Sportback. The noise sometimes occurred while accelerating, sometimes while braking and sometimes over bumps. But not every bump or even the same bumps, and not every acceleration or braking event. The noise was only present at speeds below about 45mph.

My Buick dealership replaced both rear knuckles in the hope that it was related to the lower link that causes a similar noise on the Chevy Malibu and Buick Lacrosse, TSB 18-NA-136. Unfortunately, this did not fix the noise.

I did a lot of diagnosis on my own and also with the technician. With the technician along, we would swap driving and riding in the back to get a better take on the noise and its location. We drove with the right rear door open and closed, the lift gate open, closed, or closed partially, removed interior panels including all rear interior panels and dropped the headliner, used an electronic stethoscope, and just about everything in between. We did find the noise was louder when the right rear door was open.

We eventually found a bump where we could replicate the noise each time, but only while moving forward and only when the right front wheel went over the bump first followed by the right rear wheel. Believe this is because the right front wheel flexed the body in a certain way to "reset" things and then when the right rear wheel went over the bump it flexed in a specific way to make the "pop".

We thought the noise may have been lift gate related (another user, @ready2fly, had a spot weld issue with his lift gate causing a similar noise). The technician actually got some very loud pops from the spot welds at the lift gate hinge locations on the body side by tightening the hinge nut. This, however, did not fix the noise.

A big break was when we discovered we could turn the noise on and off. By pulling on the right rear inner quarter panel brace when going over the bump, the noise would stop. Releasing pressure on this panel, and the noise would return. This was right inside of where the exterior C pillar trim appliqué lives.

After talking with multiple body shops about possible repair methods, we started by hammering each of the spot welds around this inner quarter panel area with a metal rod and hammer. This did not change or fix the noise.

During this, the technician suggested we look at the spot welds on the right rear door opening flange that the weather stripping attaches to.

There we found a spot where 4 panels (outer quarter panel, inner quarter panel brace and 2 others) meet and are spot welded together.

Using a metal dolly with a rubber cover to act as a backing plate against the outside painted portion of this flange, we hammered the spot welds on the inside at this location.

The noise was instantly gone after doing this, and it has now been 3 days of peace and solitude.

I have to give major props to my dealership and the technician for working so extensively and thoroughly with me on this.

I hope this may help anyone else who may be experiencing a similar noise that is driving them crazy.

In response - I replaced every single suspension component there is on my 2018 Buick Regal Sportback.
Finally I got tired of dealing with this noise.
I finally took it to the local Firestone.
The technician went with me for a ride.
He had asked me if the struts I replaced came with strut mounts.
And I said, I'm pretty sure I know it's strut mount says and yes it did.
He said if the struts did not come with mounts,then that is the culprit.
I even thought it was my sway bar bushings.
So everyday I turn off my radio and listen for the sound.
It is only obvious at speeds of 0 to about 40 and then it goes away.
So I just tore apart the right side.
Spot welds look fine to me.
So tomorrow morning I will be taking it for a drive, and go from there.
Hopefully the noise is still there and I can pinpoint it.