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Current: 2012 3.6L ThunderGray CTS4 | Retired Caddies [3]: 2002/1993/1994 Seville Touring Sedan
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Discussion Starter · #1 · (Edited)
Difficult to describe otherwise and not loud enough for my phone to record, but when I’m driving there is a metallic ringing like two plates spinning against each other, or like a roller going bad on a conveyor belt. It has almost a harmonic sound to it.


The car is a 2012 CTS4 performance AWD with 3.6L

The sound is most noticeable at take off (just because there is no wind/road noise) and seems to be drivetrain related, not wheel speed. I hear it when the throttle is engaged and seems to match RPM more than wheel or vehicle speed. When I take my foot off the throttle at any speed, it just goes away.
It’s most noticeable at take off (just because there is no wind/road noise) and seems to be drivetrain related, not wheel speed. I hear it when the throttle is engaged and seems to match RPM more than wheel or vehicle speed. When I take my foot off the throttle at any speed, it just goes away.

I’m completely stumped, but I want to be able to tell the seller’s service department what’s going on before my 30day bumper to bumper runs out and get it on paper so they can’t say they were never made aware of an issue so it’s not their problem.

any help would be greatly appreciated.

not sure if related, but I also get a smell that isbest described as hot weather stripping mixed with a hint of burning motor oil coming through my cabin vents, but only at idle.
\_ (•_•) _/
 

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2014 CTS4 Sport Wagon*Luxury 2016 CTS V-Sport Premium
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maybe a heat shield for the exhaust???when I start my 2014 Sport Wagon and the idle is high upon warm up, I can hear a metallic sound (something is hitting it's frequency, Kenneth)...but mine doesn't do it after the car settles in for idle or is already warmed up...if that is your issue, perhaps your heat shield is just more loose than mine...

good luck

Bill
 
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Current: 2012 3.6L ThunderGray CTS4 | Retired Caddies [3]: 2002/1993/1994 Seville Touring Sedan
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Discussion Starter · #3 ·
maybe a heat shield for the exhaust???when I start my 2014 Sport Wagon and the idle is high upon warm up, I can hear a metallic sound (something is hitting it's frequency, Kenneth)...but mine doesn't do it after the car settles in for idle or is already warmed up...if that is your issue, perhaps your heat shield is just more loose than mine...

good luck

Bill
I don’t think so. It only makes the noise under load, not at idle or any rpm in park or neutral. My initial thought was brakes for this reason and the fact that the sound is similar to brakes rubbing rotors (actually, more like rotor against rotor or a flywheel that’s too close to another heavy component). Any deeper and it would be a grinding sound, any lighter and it would be a “SHING” (pardon my use of onomatopoeia).
im not trying to be obtuse but I literally have nothing else. It’s not throwing codes and it doesn’t make the sound unless it’s moving under some kind of load. Like I said, I thought it was brakes, but as soon as load is removed from the drivetrain, the sound goes away. Put it in neutral down a short hill, nothing…it sounds expensive and I want the seller to cover it if it gets worse, but I need to cover my ass better than they are going to evade the cost
 

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front brake dust shield? flimsy crap and when tire techs mount up, they rest the tire/wheel on this and it does bend a wee bit
 

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maybe a heat shield for the exhaust???when I start my 2014 Sport Wagon and the idle is high upon warm up, I can hear a metallic sound (something is hitting it's frequency, Kenneth)...but mine doesn't do it after the car settles in for idle or is already warmed up...if that is your issue, perhaps your heat shield is just more loose than mine...

good luck

Bill
And, what's the frequency?
 
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Magoo—2012 Cadillac CTS Luxury, Opulent Blue, plus many more, see signature.
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Try some slow maneuvers in a parking lot or driveway with a helper listening (or helper driving, you outside the car listening). If it's coming from a wheel, I suspect something involving brake rotor and/or dust shield.
 

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If the noise is presenting under load, I would examine your driveshaft for any loose bolts and I also wouldn't rule out any type of heat shielding just yet.
 

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2009 CTS 3.6L DI rebuilt to FE3 J55 G80 3.42:1
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Would help if you posted the mileage. Maybe something rotating with a bad bearing, idler, tensioner, or AC clutch?
 

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Discussion Starter · #9 ·
75k miles
 

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You can remove the serpentine belt and (briefly) run the engine to rule out a problem with one of the accessories.
 

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Difficult to describe otherwise and not loud enough for my phone to record, but when I’m driving there is a metallic ringing like two plates spinning against each other, or like a roller going bad on a conveyor belt. It has almost a harmonic sound to it.


The car is a 2012 CTS4 performance AWD with 3.6L

The sound is most noticeable at take off (just because there is no wind/road noise) and seems to be drivetrain related, not wheel speed. I hear it when the throttle is engaged and seems to match RPM more than wheel or vehicle speed. When I take my foot off the throttle at any speed, it just goes away.
It’s most noticeable at take off (just because there is no wind/road noise) and seems to be drivetrain related, not wheel speed. I hear it when the throttle is engaged and seems to match RPM more than wheel or vehicle speed. When I take my foot off the throttle at any speed, it just goes away.

I’m completely stumped, but I want to be able to tell the seller’s service department what’s going on before my 30day bumper to bumper runs out and get it on paper so they can’t say they were never made aware of an issue so it’s not their problem.

any help would be greatly appreciated.

not sure if related, but I also get a smell that isbest described as hot weather stripping mixed with a hint of burning motor oil coming through my cabin vents, but only at idle.
\_ (•_•) _/
I have the same car and year and milage, I hear the same noise as well. I have not pinpointed it however after warm up it does seem to go away. I don't find any handling or issues with drivability of the car. I was thinking maybe a "U" Joint in driveshaft but hasn't bothered me enough to look for it. I have ruled out Brakes, Wheels, Tires, Steering Noise seems to be coming from the middle of the car. Good Luck if I figure it out I will let you know. I like the heat shield issue as a strong possibility.
 

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You said it is rpm related and not vehicle speed related. That means it's not wheel or brake related. You said it only does it in drive. That rules out engine and accessories on serpentine belt. That leaves transmission and transfer case. Does the noise sound like it could be coming drom there?
 

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Difficult to describe otherwise and not loud enough for my phone to record, but when I’m driving there is a metallic ringing like two plates spinning against each other, or like a roller going bad on a conveyor belt. It has almost a harmonic sound to it.

The car is a 2012 CTS4 performance AWD with 3.6L

The sound is most noticeable at take off (just because there is no wind/road noise) and seems to be drivetrain related, not wheel speed. I hear it when the throttle is engaged and seems to match RPM more than wheel or vehicle speed. When I take my foot off the throttle at any speed, it just goes away.
It’s most noticeable at take off (just because there is no wind/road noise) and seems to be drivetrain related, not wheel speed. I hear it when the throttle is engaged and seems to match RPM more than wheel or vehicle speed. When I take my foot off the throttle at any speed, it just goes away.

I’m completely stumped, but I want to be able to tell the seller’s service department what’s going on before my 30day bumper to bumper runs out and get it on paper so they can’t say they were never made aware of an issue so it’s not their problem.

any help would be greatly appreciated.

not sure if related, but I also get a smell that isbest described as hot weather stripping mixed with a hint of burning motor oil coming through my cabin vents, but only at idle.
\_ (•_•) _/

Does this sound like it?

Discussed Here

 

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You said it is rpm related and not vehicle speed related. That means it's not wheel or brake related. You said it only does it in drive. That rules out engine and accessories on serpentine belt. That leaves transmission and transfer case. Does the noise sound like it could be coming drom there?
Those items are (mostly) vehicle speed related, not engine speed.
 

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Discussion Starter · #15 ·
Does this sound like it?

Discussed Here

not like that at all.
i first suspected brakes or the dust/heat shield by the brakes.
i did a lot of testing of that theory and discovered that it only happens when I’m on the throttle. I let off the throttle, it disappears. The harder I get into it, the more prominent it becomes, but it’s quiet enough that it disappears under the engine/road noise unless I’m right next to a wall. It’s still perceptible with all the windows up and sounds like it’s coming from center forward, but I would not stake anything on that being the location. It’s never anywhere near something I would call “loud”, but it does come back in through the windows when I pull away from a stop or go uphill at it’s loudest. No throttle = no sound, regardless of braking or anything else.
maybe it’s a heat shield, I’m not ruling it out, but as I said before, if it were any lower/deeper I would describe it as a grinding noise.
 

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I agree with Lifespeed as to the best diagnostic approach

Put the car in park and play with the accelerator to get the car to reproduce the sound in idle. If it happens in park, then it's not suspension/wheel/transmission related. Then, turn the ignition off, remove the serpentine belt, restart the car, and try to reproduce the sound. If the sound reoccurs, it's in the engine; if not, it's one of the accessories driven by the belt (like the alternator) OR an idler pulley.

Good luck
 

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It's probably your rear differential, likely a bearing inside, classic telltale is that it goes away when you're off the throttle/coasting because it becomes unloaded.
 

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Discussion Starter · #18 ·
It's probably your rear differential, likely a bearing inside, classic telltale is that it goes away when you're off the throttle/coasting because it becomes unloaded.
That makes sense to me.
 

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Discussion Starter · #20 ·
That's wheel speed, not engine speed. Maybe figure out if your noise follows engine speed or wheel speed?
Let me apologize for inadequately conveying my understanding.
the sound is certainly more related to the engine than the wheels as a noise function.
It does not increase or decrease in frequency with any speed per-say, wheel, engine, or otherwise. I didn’t know how to exactly explain what I was getting from my experience. I thought I mentioned this in my original post as well as one of the replies.
what I DID know was that the sound was not coming from my brakes and not likely my hub assembly or wheels due to the fact that it only made the noise as I was applying power through the engine. It would get (marginally) louder the more I applied and would disappear without the direct application of throttle or engine empowerment, regardless of how fast the wheels were spinning. There is absolutely zero correlation between wheel speed and the noise (to be fair, after continuing to drive it, there is also zero correlation between the noise and engine speed as well) I misspoke, and for that, I apologize.

I’m on an Internet forum asking for possible diagnosis with onomatopoeia that any service shop would ask me to repeat ad-nauseam so they can laugh at how many times they got me to make a stupid noise, because (this part is going to blow your hair back)… because I am not quite a technical expert.
I know, it seems too unbelievable to comprehend, but there it is.
please excuse my plebeian lack of technical and mechanical refinement, skills, and lexicon… for not knowing what I didn’t know already and how to elaborate the context and situation surrounding the initial query to your liking.

again, any speed or velocity does not change the characteristics of the sound, from the rpm, the wheels, the computer processor, the speedo gauge, or anything. The pitch, tone, harmonics, or frequency does not shift at all either. Only volume, and it’s a minuscule change at that, and only when a load is being presented to the drivetrain. It’s only audible at low enough speeds that it isn’t overtaken with wind, road, or engine noise.

differential issues are something I have a passing familiarity with, but would have never thought of in this situation. It seems at the very least, plausible.
 
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