2018 Regal GS Exhaust Noise Issue

[MrTvor]

Hello everyone! I have a 2018 Regal GS, over the last month or so, I've started getting a strange noise from the exhaust (or so I assume). I was thinking it was the diff, like others have had issues with. But my issue happens when stopped! Basically, when idle, the car will start to vibrate (best term I can think of), a quick tap of the throttle causes it to go away, then it slowly come back over about 20 seconds. Once on the move it stops, until the car reaches 3k RPM. after 3200RPM, and before 2900RPM it doesn't do it. I have 0 codes, confirmed with an OBD reader, and a GM MDI, the only thing we saw was the rear microphone picking up a lot of noise.. Otherwise all mechanical components seem completely normal! I was wondering if anyone else has had any other issues like this?! I'm thinking its maybe the resonator..

Also should note, when outside the car, I don't hear feel the issue at all, only when inside. Sometimes its unbearable, and have to rev it just a tiny bit so it doesn't happen. If it made the car sound louder or cooler than it already is, I wouldn't have an issue with it

I appreciate your thoughts!

Happy New Year!

 

[MelsRegal]

Have you put the vehicle on a lift with someone in the driver's seat?

 

[Jack GS]

My first suggestion is to check out the exhaust shielding and exhaust mounts. It does not take much to bend the shields and once they're too close to the exhaust, they may rattle at certain RPMs and not at others due to the modal frequency of the system. It's the easiest thing to check and also the easiest to rectify.

It may even be something as simple as a foreign object lodged somewhere.

If you're in an area where salt/rust is a factor, it's possible the sound may be coming from the (potentially) corroded valve assemblies in the muffler. They are held closed by spring tension and open up when given throttle and exhaust flow increases. See this thread:

GS Mufflers Have Valves (Photo)

Maybe some of you were already aware of this, but I was looking around and found out the mufflers on the GS have valves. I could press on it and get it to rotate. There aren't any wires going to it that I could see so I believe it functions solely on pressure. At idle, they're still closed...

buickforums.com

 

[MrTvor]

My first suggestion is to check out the exhaust shielding and exhaust mounts. It does not take much to bend the shields and once they're too close to the exhaust, they may rattle at certain RPMs and not at others due to the modal frequency of the system. It's the easiest thing to check and also the easiest to rectify.

It may even be something as simple as a foreign object lodged somewhere.

If you're in an area where salt/rust is a factor, it's possible the sound may be coming from the (potentially) corroded valve assemblies in the muffler. They are held closed by spring tension and open up when given throttle and exhaust flow increases. See this thread:

GS Mufflers Have Valves (Photo)

Maybe some of you were already aware of this, but I was looking around and found out the mufflers on the GS have valves. I could press on it and get it to rotate. There aren't any wires going to it that I could see so I believe it functions solely on pressure. At idle, they're still closed...

buickforums.com

Wow! I didn't even think to check the heat shields. I will be checking all of your suggestions out tomorrow, and will report back! Little things, I didn't even think about! Interesting note on that valve, I will check that as well!

Thanks bud!

I live in Michigan, salt is definitely an issue here

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[MrTvor]

Just wanted to report back in! Took at look at it yesterday and Didn't see anything touching, rubbing, no holes or anything. I did check the valves in the exhaust, and checked to make sure they move the way they should. I went for a drive after and it seems to not be there. Although sometimes it never does it at all. I will report back later this week after going back to work, and ill see if its better. I did take a rubber mallet and gently tapped the mufflers to see if there was something loose inside them.

Thanks for the help again!

 

[LLninja]

You used the enforcer to scare the car into submission

 

[MrTvor]

I tried too! haha! Although I do have to report its done it three times this week. Its just so weird that it happens sometimes but not others. I'm going to keep an eye on it to see if there are certain conditions/times or things I'm doing, other than RPM's that cause this issue! I'm really hoping not to take it to the stealership, although I still have a year and about 12k miles on my Bumper to bumper CPO warranty.

 

[Irock1985]

Maybe not your issue but I had my exhaust replaced under warranty due to the muffler packing fibers (looks like hair) started coming out the exhaust

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[MrTvor]

Maybe not your issue but I had my exhaust replaced under warranty due to the muffler packing fibers (looks like hair) started coming out the exhaust

Did they replace the entire exhaust? When did this happen? How long did it take them? Sorry for the 3 questions, I'm just curious in case I need to do this!

 

[Irock1985]

Did they replace the entire exhaust? When did this happen? How long did it take them? Sorry for the 3 questions, I'm just curious in case I need to do this!

Entire exhaust: no just from the muffler back

When: around 25k-30k

Time to repair: well it took a few days for the part to come in and then they actually sent it out to a muffler shop because I guess they don't do that type of welding at my dealership but it only took them a few hours.

You would absolutely realize if you needed this because you would have hairs hanging out the back of your car... I mean you might not notice it right away because some do actually just blow out but eventually they just start hanging out the back

 

[MrTvor]

Entire exhaust: no just from the muffler back

When: around 25k-30k

Time to repair: well it took a few days for the part to come in and then they actually sent it out to a muffler shop because I guess they don't do that type of welding at my dealership but it only took them a few hours.

You would absolutely realize if you needed this because you would have hairs hanging out the back of your car... I mean you might not notice it right away because some do actually just blow out but eventually they just start hanging out the back

Thanks for the reply! I was just curious, as I don't want to be without my car for more than a day or so! My dads thoughts are that they will probably have to replace the entire exhaust.. but im not sure after what you said, depends on if they can locate the issue of not. I guess that what warranty is for though. I have almost 52k miles on the clock. I bought it with 38k. I definitely don't have your issue, although that certainty is a weird one, I've never heard of that happening before!

Appreciate the input!

 

[MelsRegal]

Thanks for the reply! I was just curious, as I don't want to be without my car for more than a day or so! My dads thoughts are that they will probably have to replace the entire exhaust.. but im not sure after what you said, depends on if they can locate the issue of not. I guess that what warranty is for though. I have almost 52k miles on the clock. I bought it with 38k. I definitely don't have your issue, although that certainty is a weird one, I've never heard of that happening before!

Appreciate the input!

You have an extended warranty?

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[MrTvor]

You have an extended warranty?

Got my car Certified Pre Owned last year from a dealer. Gets 1 year/12k miles Bumper to Bumper. And 6yr/100k Mile Powertrain.
See: This PDF from Buick
I feel like mine was 2yr on the bumper to bumper, ill have to check my paperwork again.

 

[abizzle]

My first suggestion is to check out the exhaust shielding and exhaust mounts. It does not take much to bend the shields and once they're too close to the exhaust, they may rattle at certain RPMs and not at others due to the modal frequency of the system. It's the easiest thing to check and also the easiest to rectify.

While I was soundproofing the rear wheel wells, I noticed how flimsy the heat shields were. If you tap them with your finger they make quite a bit of noise. I made a mental note of them being a possible source for unwanted noise in the future. In fact, I’m amazed they don’t rattle when my subwoofers are bumpin.