Growling noise when accelerating from a stop....

2023 Niro SX: never.

While you are at the dealer tonmorrow, have them check the clutch fluid reservoir for contamination.

I'll do that. I just re-read your post about the suspected leak from that clutch fluid reservoir and the contamination. I'll check this before I go to the dealer tomorrow so I can see for myself first if it looks overly full or discolored. What would you suspect would be the link between an issue with that system and the noise as I described? If I'm taking off from a complete stop while the ICE is off and the ICE starts up upon initial acceleration, would that possibly cause that sound because the hydraulics might not be properly lubricated? I'm not a car guy at all but I appreciate your input.

Denman said:

I'll do that. I just re-read your post about the suspected leak from that clutch fluid reservoir and the contamination. I'll check this before I go to the dealer tomorrow so I can see for myself first if it looks overly full or discolored. What would you suspect would be the link between an issue with that system and the noise as I described? If I'm taking off from a complete stop while the ICE is off and the ICE starts up upon initial acceleration, would that possibly cause that sound because the hydraulics might not be properly lubricated? I'm not a car guy at all but I appreciate your input.

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There would not be a link between the clutch fluid and the growling noise.
Might it possibly be a rear brake rotor noise as the rear rotors tend to rust quickly due to non-use because of regen braking?

Techy said:

There would not be a link between the clutch fluid and the growling noise.
Might it possibly be a rear brake rotor noise as the rear rotors tend to rust quickly due to non-use because of regen braking?

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That's a good point! I've been using the regen braking paddle quite often to come to a complete stop and have been trying to avoid brake use perhaps more than I should. Is there a quick way to get rid of the rust that might be building up? Perhaps some more aggressive braking techniques for a while?

Denman said:

That's a good point! I've been using the regen braking paddle quite often to come to a complete stop and have been trying to avoid brake use perhaps more than I should. Is there a quick way to get rid of the rust that might be building up? Perhaps some more aggressive braking techniques for a while?

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If you read the owners manual it will mention a method to use that involves (I believe) the auto hold feature.
On my HEV, at least once per week, I will put the car in neutral at good speed and use the friction brakes to bring to a stop. Do not do this in traffic.

Techy said:

If you read the owners manual it will mention a method to use that involves (I believe) the auto hold feature.
On my HEV, at least once per week, I will put the car in neutral at good speed and use the friction brakes to bring to a stop. Do not do this in traffic.

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Thanks. I'll check the manual about that method and also try your braking idea as well when it's safe to do so. So, if there's rust on the rotors, why would I only hear that when accelerating from a stop? I guess the pads might still be engaged (even with the auto hold feature on?) for just a second as I start moving and the rust against the pad could result in that noise?

Denman said:

Thanks. I'll check the manual about that method and also try your braking idea as well when it's safe to do so. So, if there's rust on the rotors, why would I only hear that when accelerating from a stop? I guess the pads might still be engaged (even with the auto hold feature on?) for just a second as I start moving and the rust against the pad could result in that noise?

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Ya, I am not sure why you would hear it when accelerating - that has me bewildered.
On mine, I hear it when backing out of my garage and it is worse when I press on the brake pedal.
I do sometimes hear a little noise when accelerating from my driveway (again, 1st time in the day) but that usually stops quickly and I don't notice it again that day.
I really don't think you have a problem to worry about but I understand your concern. At least it is a new car and fully covered under warranty, should a problem arise.

Techy said:

Ya, I am not sure why you would hear it when accelerating - that has me bewildered.
On mine, I hear it when backing out of my garage and it is worse when I press on the brake pedal.
I do sometimes hear a little noise when accelerating from my driveway (again, 1st time in the day) but that usually stops quickly and I don't notice it again that day.
I really don't think you have a problem to worry about but I understand your concern. At least it is a new car and fully covered under warranty, should a problem arise.

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I feel relieved and now I'll have more information when I visit the service department tomorrow. I really love this forum and everyone's collective experience. I'll check the clutch fluid color as well and try to raise up the hood to have a look more than once every few months to get the leaves out! LOL

In one of your posts I believe I read you hear the noise when acclerating and then the ICE kicks in. By chance does the noise go away when the ICE kicks in? Does the noise occur when you first accelerate easy when the car is on battery only?

For me the key phrase is a noise"somewhere in the rear lower area". That does not correspond with anything ICE or motor on a FWD vehicle.
That is why I suggested maybe it is a brake thing

FlNiro said:

In one of your posts I believe I read you hear the noise when acclerating and then the ICE kicks in. By chance does the noise go away when the ICE kicks in? Does the noise occur when you first accelerate easy when the car is on battery only?

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The noise is definitely coming from the back area. When someone mentioned the issue with the clutch fluid contamination which is part of the system switching between the battery and ICE, I was just thinking out loud about how they might be related to the noise. Although I will be checking the fluids tomorrow, I'm quite sure that the rusty rotor is likely the cause. I'm starting to think my mechanical brakes likely get little to no use because I'm a very light and gradual braker and I suppose I've been mostly using generation to stop the car since I got it in October. I'm getting close to 4K miles and overall I've been very pleased with the vehicle. My first significant road trip with it is coming up soon and I'm looking forward to it!

I would think it's probably surface rust on the rotors but I asked about the ICE being on when you accelerate to check to make sure it's not the "space ship" noise the car emits when it's under battery only power. The sound is in front but you'd be surprised how noise travels and if the speaker thing got lose or dislodged somehow it could make it sound like it's coming from the back???

I think this is probably the same issue as these:

Denman said:

Thanks. I'll check the manual about that method and also try your braking idea as well when it's safe to do so. So, if there's rust on the rotors, why would I only hear that when accelerating from a stop? I guess the pads might still be engaged (even with the auto hold feature on?) for just a second as I start moving and the rust against the pad could result in that noise?

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Use the brake cleaning mode by pressing autohold for 5+ secs - you will see an indication in the dashboard

Thanks everyone! I'll try all these things and let you know if the sound ceases.

I spoke with one of the key Kia service tech guys today at my dealership. All the fluids looked fine to him and although there was slight discoloration to the clutch fluid in the front reservoir he said it's in line with what he would expect and that it would be replaced (I'm not sure if that means "flushed") during my 15K service interval. When I described the sound from the back end he said there's a chance that air may have gotten into the brake system lines (I'm not quite sure of the exact lingo he used) and that if it continued they would take care of it by flushing it out or some such thing. He did encourage me to try the braking cleaning mode and other things you've described here but I just got the sense that based on my description of what it sounded like and when it occurred that it might not be the "rotor rust". Whatever it is didn't seem urgent and if it continues I'll have it checked when I do my first oil change after my next 2K trip.

Denman said:

I spoke with one of the key Kia service tech guys today at my dealership. All the fluids looked fine to him and although there was slight discoloration to the clutch fluid in the front reservoir he said it's in line with what he would expect and that it would be replaced (I'm not sure if that means "flushed") during my 15K service interval. When I described the sound from the back end he said there's a chance that air may have gotten into the brake system lines (I'm not quite sure of the exact lingo he used) and that if it continued they would take care of it by flushing it out or some such thing. He did encourage me to try the braking cleaning mode and other things you've described here but I just got the sense that based on my description of what it sounded like and when it occurred that it might not be the "rotor rust". Whatever it is didn't seem urgent and if it continues I'll have it check when I do my first oil change after my next 2K trip.

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Who am I to question the tech guy's diagnosis of "air in the brake lines" but I can say with 100% certainty that is a load of BS.
I will agree with his sense of no urgency.

Okay, I'll let you know once I get those brake pads exercised a bit. However I didn't get the sense that he was just feeding me BS to get rid of me. I still have faith in dealerships to ultimately help solve problems although on occasion these online forums would lead one to believe that they are not to be trusted. By relaying what he said based on what I said leaves a lot of "gray area" in there that then gets even grayer when I discuss it online. I would certainly never trust a 3rd party mechanic to work on my new vehicle. I learned the hard way with a VW quite a few years ago when one of them (who "specialized in VW service" pulled the tranny plug instead of the oil plug when doing a simple oil change. That led to my car being towed to the dealership to correct that "little mistake".

Denman said:

Okay, I'll let you know once I get those brake pads exercised a bit. However I didn't get the sense that he was just feeding me BS to get rid of me. I still have faith in dealerships to ultimately help solve problems although on occasion these online forums would lead one to believe that they are not to be trusted. By relaying what he said based on what I said leaves a lot of "gray area" in there that then gets even grayer when I discuss it online. I would certainly never trust a 3rd party mechanic to work on my new vehicle. I learned the hard way with a VW quite a few years ago when one of them (who "specialized in VW service" pulled the tranny plug instead of the oil plug when doing a simple oil change. That led to my car being towed to the dealership to correct that "little mistake".

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As long as your vehicle is under warranty, I support taking it to the dealer. But if you have a trusted non-dealer mechanic, I would always take a non warranty car to them and in some circumstances even take a fairly new car for a 2nd opinion. There are good dealership service people out there but they are becoming fewer in number - it is all about profit! Be careful when taking your car to the dealer for non warranty work. It is not uncommon for them to expand the "maintenance schedule" with a list of "recommended" items that are pure profit generators.

As a licensed tech (retired) myself, I again state that air in the brake lines will never cause a noise - only affect brake operation and with the addition of regen, I am not so sure air in the brake lines would even be noticed. Air cannot get into the brake system unless it has been "opened" or there is a leak and that does not happen on a new car.