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Discussion Starter #1
Thinking of upgrading to a HC. Took one for a test drive the other day on an open stretch of highway.
Under heavy acceleration at high speed I noticed an audible clattering/rattle sound coming from engine, in front of glove box area. Sounds like valve-train type noise, or like engine knock, but highly doubt the latter since the owner always fuels with Shell V-Power or BP Ultimate. Only happened while accelerating. Is this one of those "it's normal on a HC" things? Or a red flag?
 

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The Pork Wagon (‘14 Cop Charger)
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Not normal that I ever heard anyone say. If it was loud enough to be heard while under a heavy acceleration, that is disconcerting, to me anyway.

But then again, I don’t own a HC nor have I driven one, so maybe I’m just talking out my keester...
 

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Valve-train noise usually is a consistent tick throughout rpms. Wonder if the passenger side catalytic converter is damaged as it is in the area where you are hearing the noise?
 

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Discussion Starter #4
Valve-train noise usually is a consistent tick throughout rpms. Wonder if the passenger side catalytic converter is damaged as it is in the area where you are hearing the noise?
No damage to the cc. The only consistency is that it happened under heavy, high-speed acceleration, for a few seconds, until down-shifting.
 

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No damage to the cc. The only consistency is that it happened under heavy, high-speed acceleration, for a few seconds, until down-shifting.
Yeah but how do you know for sure, did you inspect visually inside that cat? There is a reason for COT to keep cats from melting. Valve-train noise does not just come on at hard acceleration, it usually can still be heard at idle or cruising at around 1500-2000 rpm.

Could it be a loose heat shield?
 

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Discussion Starter #6
Yeah but how do you know for sure? There is a reason for COT to keep cats from melting. Valve-train noise does not just come on at hard acceleration, it usually can still be heard at idle or cruising at around 1500-2000 rpm.
I know because I know the seller very well. Car is fairly new (2019) and he keeps it immaculate.
 

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So then why are you suspecting valve-train if the owner keeps the car immaculate? Keeping a car show quality does not prevent a part from failing.

 

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Discussion Starter #8
So then why are you suspecting valve-train if the owner keeps the car immaculate?
Just because it's immaculate doesn't necessarily mean there isn't a mechanical defect.
 

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Just because it's immaculate doesn't necessarily mean there isn't a mechanical defect.
Exactly, so why do you believe the cats are fine but valve-train is not? Check my edited post.

BTW it is interesting in that thread I posted that someone asked if race fuel was run in the car. In my area all the "race" fuel is leaded.

Another thing to check...could it be active exhaust related?
 

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Discussion Starter #10
Exactly, so why do you believe the cats are fine but valve-train is not? Check my edited post.

BTW it is interesting in that thread I posted that someone asked if race fuel was run in the car. In my area all the "race" fuel is leaded.
Just confirmed, there was no damage to cc....and no race fuel was ever used.
 

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Just confirmed, there was no damage to cc....and no race fuel was ever used.
How are you confirming the catalyst is not damaged? You have to look down the pipe of the cat. Anyways, check active exhaust flaps for looseness as well or check that the springs holding the cats to the manifold are not loose. If you still think it is valve-train, hold rpm at around 2k...if no ticking then probably not the source.
 

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Discussion Starter #13
How are you confirming the catalyst is not damaged? You have to look down the pipe of the cat. Anyways, check active exhaust flaps for looseness as well or check that the springs holding the cats to the manifold are not loose. If you still think it is valve-train, hold rpm at around 2k...if no ticking then probably not the source.
I know the seller very well. By "confirming," I meant there was no physical damage from owner, and he purchased new.
I'll check out the other things you mentioned....and try to get sound clip.
Thanks for the info!
 

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I know the seller very well. By "confirming," I meant there was no physical damage from owner, and he purchased new.
I'll check out the other things you mentioned....and try to get sound clip.
Thanks for the info!
Geez, I am not talking about the owner running over something causing physical damage to the cat...I am talking that the honeycomb catalyst inside the cat could have overheated or had a defect from the start. For that you have to look into the mid-pipe where the cat is welded to. If the catalyst is loose you can get into a situation where it rattles and high heat during accel along with a lot of exhaust flow could stir things up.

The cat sits just by the passenger side footwell which is directly below the glove box...which is why I targeted the cat. Again if it was valve-train, like a bad lifter, they usually tend to stay noisy throughout the rpm range. They don't rattle but they do tick/tap like crazy when they are bad.

The cats are held on by a 2 bolts that have springs to keep tension, there are also heat shields that could have loosened as well that vibrate at hard accel.
 

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Discussion Starter #15
Geez, I am not talking about the owner running over something causing physical damage to the cat...I am talking that the honeycomb catalyst inside the cat could have overheated or had a defect from the start. For that you have to look into the mid-pipe where the cat is welded to. If the catalyst is loose you can get into a situation where it rattles and high heat during accel along with a lot of exhaust flow could stir things up.

The cat sits just by the passenger side footwell which is directly below the glove box...which is why I targeted the cat. Again if it was valve-train, like a bad lifter, they usually tend to stay noisy throughout the rpm range. They don't rattle but they do tick/tap like crazy when they are bad.

The cats are held on by a 2 bolts that have springs to keep tension, there are also heat shields that could have loosened as well that vibrate at hard accel.
Makes sense. Wouldn't it throw a code if bad?
 

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Makes sense. Wouldn't it throw a code if bad?
May not. There was another thread I read a while back where a guy was revving the piss out of his engine (it was SRT but don't recall if it was 6.2 or 6.4) and catalyst bits blew out...no codes.

BTW - cat efficiency is not monitored during hard accel.
 

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ChallyTatum has offered up some good advice.

Why is the owner selling the car? A relatively new 2019 RE?

Is the car mod'd?

My general advice is with a used car if the car manifests some signs of trouble and this noise you describe fits the bill to walk away.

In this case being the car is new and has a new car warranty if you want to go through the trouble insist the seller have the car in and the car checked out this noise checked out even if he has to take the shop foreman on a ride along.

You want the noise sorted out, gone, and the car's operation to reflect its newness.

Or walk away.

The first rule of used car buying is there is always another car.
 

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The noise I heard definitely had a rotational dynamic character when exhibited, it went away as soon as it was put into gear (A8) Possibly torque converter impeller, broken dampener spring? something that can rattle until loaded (in gear)
 

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Discussion Starter #19
ChallyTatum has offered up some good advice.

Why is the owner selling the car? A relatively new 2019 RE?

Is the car mod'd?

My general advice is with a used car if the car manifests some signs of trouble and this noise you describe fits the bill to walk away.

In this case being the car is new and has a new car warranty if you want to go through the trouble insist the seller have the car in and the car checked out this noise checked out even if he has to take the shop foreman on a ride along.

You want the noise sorted out, gone, and the car's operation to reflect its newness.

Or walk away.

The first rule of used car buying is there is always another car.
More like a new 2020 Trackhawk.
Negative on the mods.
True...always another car. But some of those others have the same, or worse issues, and I'm referring to new ones.
 

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More like a new 2020 Trackhawk.
Negative on the mods.
True...always another car. But some of those others have the same, or worse issues, and I'm referring to new ones.
Just because you happen to come upon a new car or two with issues, and worse issues than the one you found with this car, is no reason to buy a car with an issue.

Have to ask. What kind of issues are you finding with new cars?

In all my years of car shopping the only time I encountered a new car with an issue is back in 2000 when I was shopping for a Camaro I came upon a new Camaro SS that when the salesman started the engine it was clear the exhaust system had some problem. The car made a heck of a racket. I looked at the salesman with a what the heck is going on look and he replied but I couldn't hear him. I'm sure it was along the lines of "they all do that"....

Needless to say I walked.
 
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