GT S faint knocking sound intermittent
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AMG GT S
GT S faint knocking sound intermittent
Sorry if this has been discussed already. I did a little searching and could not find much. Car is a 2016 GT S
Anyway, I'm wondering if this sound is normal or if I should bring the car in. Occasionally, once I've been driving for several minutes and the car is fully warmed up, usually sitting in traffic or going slow through a parking lot I will hear this VERY faint knocking sound coming from the engine. It's not the AC or anything and it definitely coincides with the engine RPMs, but it doesn't sound overly "bad." I actually originally phrased the post as a "ticking" sound but decided to use "knocking" since I guess that is only slightly more accurate. It's so quiet that I actually can't hear it when I open the hood -- only when I'm in the cabin and going slow or stopped. It never makes this sound when cold, and only sometimes does it when warm. I'll be pulling into a parking lot and hear the sound come on, and then when I come back to my car later the sound is gone. I've done several hard pulls and the car seems to run fine. I loathe bringing my car to the dealer here so I thought I'd ask you guys first. Maybe it's a common thing? Or should I have it checked out?
Thanks
Anyway, I'm wondering if this sound is normal or if I should bring the car in. Occasionally, once I've been driving for several minutes and the car is fully warmed up, usually sitting in traffic or going slow through a parking lot I will hear this VERY faint knocking sound coming from the engine. It's not the AC or anything and it definitely coincides with the engine RPMs, but it doesn't sound overly "bad." I actually originally phrased the post as a "ticking" sound but decided to use "knocking" since I guess that is only slightly more accurate. It's so quiet that I actually can't hear it when I open the hood -- only when I'm in the cabin and going slow or stopped. It never makes this sound when cold, and only sometimes does it when warm. I'll be pulling into a parking lot and hear the sound come on, and then when I come back to my car later the sound is gone. I've done several hard pulls and the car seems to run fine. I loathe bringing my car to the dealer here so I thought I'd ask you guys first. Maybe it's a common thing? Or should I have it checked out?
Thanks
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AMG GT S
No one else has experienced this at all? Guess I may have to take it in.
It's just so faint/only happens once in awhile, that I thought I'd check here first to see if it's worth any fuss. Hard to tell if I'm just being paranoid or if I'm hearing the very early stages of a rod knock or lifter problem. As I said, can't even hear it when I open the hood -- only in the cabin. These cars and engines are so complex that I wouldn't be surprised if I'm just hearing some regular process.
It's just so faint/only happens once in awhile, that I thought I'd check here first to see if it's worth any fuss. Hard to tell if I'm just being paranoid or if I'm hearing the very early stages of a rod knock or lifter problem. As I said, can't even hear it when I open the hood -- only in the cabin. These cars and engines are so complex that I wouldn't be surprised if I'm just hearing some regular process.
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2018 Solarbeam Yellow AMG GTS
I’ve never heard any knocking. Are you using 93 octane gas? Did you get water in the gas tank? Is it fresh gas or gas the car been sitting a lot for a while?
try some gas additive and see if it goes away.
try some gas additive and see if it goes away.
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AMG GT S
Thanks for the input.
Just filled it up a few days ago and have driven half a tank since. I try to get Shell whenever I can but I have filled it with other brands a couple times. Always 93 octane and I'm fairly certain I have never gotten water in the tank. The car is a garage queen for 3/4 of the month and then I drive it hard for a week, detail it, put it away, repeat. Maybe sitting for 2-3 weeks a month could be detrimental but I'd think it would take longer than that. I just took it out, got it up to temp, didn't hear the noise at all, and checked the oil when I got home -- levels are great and color is good -- this car seems to keep oil a lot cleaner than my previous sports cars! 2014 sti and 2016 z06. Should I even bother with the additive considering those factors? I live in Florida and the car regularly gets up into the 220s. I always drive in race mode, manual, TC off etc. and since this sound always comes on at low speeds when the oil temp is over 225, makes me wonder if it's just some kind of timing thing the car does when it gets angry about having to sloth it's way through Craplando traffic. I have noticed that it does really like to go fast, and seems to run much cooler when able to stretch its legs.
TLDR; I *think* my fuel is fine. Oil looks great, car runs great, and only makes this (very faint) noise occasionally but when it does I become concerned a bit as the rhythm does coincide with engine RPM. Still on the fence as to whether I should just continue to enjoy it or start hunting for a "problem."
Just filled it up a few days ago and have driven half a tank since. I try to get Shell whenever I can but I have filled it with other brands a couple times. Always 93 octane and I'm fairly certain I have never gotten water in the tank. The car is a garage queen for 3/4 of the month and then I drive it hard for a week, detail it, put it away, repeat. Maybe sitting for 2-3 weeks a month could be detrimental but I'd think it would take longer than that. I just took it out, got it up to temp, didn't hear the noise at all, and checked the oil when I got home -- levels are great and color is good -- this car seems to keep oil a lot cleaner than my previous sports cars! 2014 sti and 2016 z06. Should I even bother with the additive considering those factors? I live in Florida and the car regularly gets up into the 220s. I always drive in race mode, manual, TC off etc. and since this sound always comes on at low speeds when the oil temp is over 225, makes me wonder if it's just some kind of timing thing the car does when it gets angry about having to sloth it's way through Craplando traffic. I have noticed that it does really like to go fast, and seems to run much cooler when able to stretch its legs.
TLDR; I *think* my fuel is fine. Oil looks great, car runs great, and only makes this (very faint) noise occasionally but when it does I become concerned a bit as the rhythm does coincide with engine RPM. Still on the fence as to whether I should just continue to enjoy it or start hunting for a "problem."
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18 AMG GTC and 22 F150 Limited. Past owner 16 Maybach, 17 Brabus Smartcar, 06 Ford E150, and 22 G70
My GTC makes a pecular clicking sound that is perhaps what your talking about. You can hear it at the stop lights. Its very quiet but you can hear it. I suspect its of no significance.
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2023 Urus Performante 2018 Huracan Perf. - 2017 Ferrari 488 GTB
Perhaps this might shed some light. I had the same sound you are describing in my C63 S. It wasn't all of the time. It turns out, it is a normal sound/function of the fuel evaporative system. According to the dealer. Maybe some solenoid opening/closing something in the system? I do agree it sounded more like a light tick instead of a knock.
Last edited by benzbell; Oct 21, 2019 at 10:30 AM. Reason: text
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BMW M3 cabrio
I have had this on and off in my 2020 GT63, but in my case it's more of a knock sound and you can feel it pretty distinctly if you put you hands on the engine, I was kinda ignoring it but now I think it definitely needs to go in, has gotten louder and more frequent.
Only happens when engine is cold, sounds very distinctly like something is loose and being tossed around under there (although I really don't sense that that's the case.) Used Carly to try and see what Carly app said about it (I mean if it's even remotely like a combustion problem-- surely some sensors would be going off? Am I off on that?) — but Carly reports no issues (using “2020 E class” and GT Roadster” for the scans, so certainly not perfect test.)
I take it zero doubt I gotta get it to the dealer, stat? Thanks!
Only happens when engine is cold, sounds very distinctly like something is loose and being tossed around under there (although I really don't sense that that's the case.) Used Carly to try and see what Carly app said about it (I mean if it's even remotely like a combustion problem-- surely some sensors would be going off? Am I off on that?) — but Carly reports no issues (using “2020 E class” and GT Roadster” for the scans, so certainly not perfect test.)
I take it zero doubt I gotta get it to the dealer, stat? Thanks!
Last edited by JonDiamond; Jul 25, 2021 at 10:00 PM.
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2018 Diamond White GT-R
I have had this on and off in my 2020 GT63, but in my case it's more of a knock sound and you can feel it pretty distinctly if you put you hands on the engine, I was kinda ignoring it but now I think it definitely needs to go in, has gotten louder and more frequent.
Only happens when engine is cold, sounds very distinctly like something is loose and being tossed around under there (although I really don't sense that that's the case.) Used Carly to try and see what Carly app said about it (I mean if it's even remotely like a combustion problem-- surely some sensors would be going off? Am I off on that?) — but Carly reports no issues (using “2020 E class” and GT Roadster” for the scans, so certainly not perfect test.)
I take it zero doubt I gotta get it to the dealer, stat? Thanks!
Only happens when engine is cold, sounds very distinctly like something is loose and being tossed around under there (although I really don't sense that that's the case.) Used Carly to try and see what Carly app said about it (I mean if it's even remotely like a combustion problem-- surely some sensors would be going off? Am I off on that?) — but Carly reports no issues (using “2020 E class” and GT Roadster” for the scans, so certainly not perfect test.)
I take it zero doubt I gotta get it to the dealer, stat? Thanks!
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BMW M3 cabrio
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Schwinn
Why ? Doesnt hurt to ask if you are concerned Drive in to the service bay, ask your SA hey can you listen to this real quick. If its something he cant diagnose with his little ears, then a AMG tech will be able to tell you on the spot if its serious or "Fuel Injectors make a lot of noise, nothing to worry about"
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BMW M3 cabrio
So, the car went in and was diagnosed as misfire in cylinder 8. They called for and did new injector and plug. Unfortunately, it turns out that that was incidental, I guess, to the noise, which is still present and they are figuring out what to do next.
I have a somewhat good video that gives -some- idea of the noise, will see if I'm able to upload it here.
I have a somewhat good video that gives -some- idea of the noise, will see if I'm able to upload it here.
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Schwinn
To me that sounds like a bad pulley bearing. Like on an alternator, or idler pulley, AC compressor. Thats easy to diagnose, they pull the belt off and spin pulleys by hand to hear if they make noise. So, they fixed the misfire but have not been able to diagnose that noise yet? Is that what you are saying.
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BMW M3 cabrio
To me that sounds like a bad pulley bearing. Like on an alternator, or idler pulley, AC compressor. Thats easy to diagnose, they pull the belt off and spin pulleys by hand to hear if they make noise. So, they fixed the misfire but have not been able to diagnose that noise yet? Is that what you are saying.
THANK YOU for your input! I will pass it along immediately (and hopefully something they are already trying, based on the sound.)
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Schwinn
I'd say it as; they were laser-focused on the misfire once they diagnosed it and only this morning when they started it up and found out the sound was still present even after misfire was corrected did they even start looking for anything else, so entirely possible they have already started down the path you mention. I actually mentioned AC compressor to them as a local -really- expert BMW mechanic instantly said "have them check the AC compressor" as soon as he saw the video, told me to try starting it up w/o AC on as a possible test, which I did, but knocking was still there when I did, FWIW.
THANK YOU for your input! I will pass it along immediately (and hopefully something they are already trying, based on the sound.)
THANK YOU for your input! I will pass it along immediately (and hopefully something they are already trying, based on the sound.)
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BMW M3 cabrio
Even if you start without AC switched on thats only the clutch not engaging, the bearing is still turning. I am sure (hopeful) that the AMG tech will do it the way I mentioned. it could be something as simple as a belt Idler pulley as well but the only way to rule any of that out is to free spin all things that turn by hand and are spun by the belt. Good luck, I am sure its annoying the hell out of you by now. If I heard my AMG knock or make noise i would push it to the dealer. LOL
So, full confidence in the repair process and the competence at this dealer. At. This. Exact. Moment. Anyway.
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2018 Diamond White GT-R
So, the car went in and was diagnosed as misfire in cylinder 8. They called for and did new injector and plug. Unfortunately, it turns out that that was incidental, I guess, to the noise, which is still present and they are figuring out what to do next.
I have a somewhat good video that gives -some- idea of the noise, will see if I'm able to upload it here.
I have a somewhat good video that gives -some- idea of the noise, will see if I'm able to upload it here.
Last edited by 57 GTR; Aug 11, 2021 at 09:31 PM.
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BMW M3 cabrio
I am confused,lol The first diag was cyl.8 where they replaced injector and plug, correct? Now they are going to 4 and replacing a coil and plug. First why not the coil on 4 and second why not the injector on 8? Is you pic plug 4 or 8? A faulty coil could cause the black condition of that plug and as user33 states bad injector.
Then, dunno why they went lookin' at cyl.4, but they did and found the plug in that condition (no idea how the plug removed from 8 looked,) and I think the way they discovered this condition in 4 was "pull all the plugs and look at 'em"
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2018 Diamond White GT-R
LOL,Your fine, I edited my post just as you were posting your reply..........I wonder if they pulled all 8 and what 8 looked like? Sounds a little like shotgun troubleshooting so why not swap out all 3,plug, injector,coil for both cylinders?
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From: Chicagoland
Schwinn
Hope that fixes this problem you have been having, the plug being black like that means either the plug wasnt firing or the injector was dumping fuel like crazy and it couldnt fire and it fouled it out. I am baffled as to why the ECM did not detect a misfire in that particular cylinder as it must have misfired numerous times and that Cyl # 8 was the one that threw the code and this one didnt. Hope the tech didnt mix up #4 and #8 positions. Weird. You didnt notice any missing/hesitation at idle or accelarating? Fingers crossed they get your car back to you knock free and you can enjoy driving it again.
