Rattle from engine when accelerating (sounds like keys)

[DailyMoparGuy]

I guess I'm glad to know I'm not alone with the odd engine noise. Unfortunately, mine doesn't sound like the other descriptions or either video linked. My 1st impression of mine was more like "dieseling" when you don't down shift with a stick. Now I'd say it's more of a flutter, and very brief. Maybe a second long.

As someone else mentioned, no code, so they have no clue what it is, even though they were able to hear it. Mine can happen really at any speed. Definitely not only while accelerating. I've heard it at 30, and 65+ on the highway. It's really starting to get on my nerves. Can't always have the radio volume at 25.

As for flashing the system, they've done that twice since I reported the issue. No help, and seems to me it made my shift points worse. I've had 35s since day one with stock 3.73, Gas mileage dropped from 18-20 to 15-17. Rarely see 8th gear any more. Wasn't always the case.

Yup I got a flutter-like noise in the 3.6L before any service at all was done to it. I can only hear it at low speeds when accelerating or coming to a stop.

It’s gotten quieter since the first day I heard it about 2 weeks ago. Truck drives fine and I’ve only ever heard it in the morning.

Edit: To clarify, I don’t know if the noise is actually “in” the engine, I just stated the engine type for reference. The noise doesn’t sound metal on metal at all.

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[ShadowsPapa]

Note from mechanic “Found and removed keys, rattle gone”.
(old Navy maintenance control joke)

Not always a joke - a college friend had a Chevy Luv truck (yeah, but I still thought it was a good friend). He said it developed a rattle. He was also in college for automotive..........
Anyway, he'd taken it to the dealer, he'd taken it to a general repair shop, no one could find the rattle. He'd looked all over, even took door panels off, could not find it.
So we were going to hit the bar over lunch one day - he drove. About half way there I heard a sound - reached up under the seat and pulled out his rattle. An empty pop can.

 

[legacy_etu]

Not always a joke - a college friend had a Chevy Luv truck (yeah, but I still thought it was a good friend). He said it developed a rattle. He was also in college for automotive..........
Anyway, he'd taken it to the dealer, he'd taken it to a general repair shop, no one could find the rattle. He'd looked all over, even took door panels off, could not find it.
So we were going to hit the bar over lunch one day - he drove. About half way there I heard a sound - reached up under the seat and pulled out his rattle. An empty pop can.

I hope he bought you a beer for finding that!!

 

[flipmode]

I guess I'll add mine to the list now.

Just rolled over 20,000 miles, regular oil changes, no codes. I've run 93 octane for a few weeks now and it still sounds exactly like LoJac's recording:



Starting the dealer diagnostic BS this week, so I'll share the results if they are interesting or helpful.

An update: So the dealer diagnostic was useless as expected, took three days for them to say they "cant recreate the problem, and that nothing is wrong". It rattled on the way out of the parking lot. Does anyone know some specific items I could ask them to check? Cam timing, or knock sensors maybe. I'm not really sure where to point them.

Also, and this could be anecdotal, but they recorded my problem as a 'transmission concern'. Now I can clearly observe the noise coming from the engine bay and I made it abundantly clear to them what I was concerned about (I wrote it down for them and handed them a paper with my description and concern, and they very annoyingly wrote down something very different). When my warranty expires and my timing chains fly off, will they look at this and say I never brought any engine concerns to their attention during my warranty period?

Thanks All,

 

[LoJac963]

An update: So the dealer diagnostic was useless as expected, took three days for them to say they "cant recreate the problem, and that nothing is wrong". It rattled on the way out of the parking lot. Does anyone know some specific items I could ask them to check? Cam timing, or knock sensors maybe. I'm not really sure where to point them.

Also, and this could be anecdotal, but they recorded my problem as a 'transmission concern'. Now I can clearly observe the noise coming from the engine bay and I made it abundantly clear to them what I was concerned about (I wrote it down for them and handed them a paper with my description and concern, and they very annoyingly wrote down something very different). When my warranty expires and my timing chains fly off, will they look at this and say I never brought any engine concerns to their attention during my warranty period?

Thanks All,

Is it the same noise from my video? If so I don't think they is anything to be done. It seems more and more people are experiencing the same noise. I can easily recreate the noise while driving slowly with a gentle acceleration between 2nd and 3rd. I can make it rattle every time. I honestly have no clue what it could be and have ZERO intention on taking it to the dealer since I'm sure they will pull the same BS.

 

[DAVECS1]

It is tip in spark knock due to cam phazing. They are using some scavenging setup were bank 1 and 2 are at different intake angles at low load. Problem is durong light load tip in the cams cannot correct fast enough to stop the momentary preignition from having the cylinders locked up.

 

[ShadowsPapa]

It is tip in spark knock due to cam phazing. They are using some scavenging setup were bank 1 and 2 are at different intake angles at low load. Problem is durong light load tip in the cams cannot correct fast enough to stop the momentary preignition from having the cylinders locked up.

Preignition or detonation? Preignition caused by hot spots before spark, detonation caused by colliding flame fronts.

Still odd that I've never heard any rattle of any sort in any of our Jeeps and truck me, when my wife is with me in our Jeeps, you end up with it shifting sooner than normal and the RPM much lower than when I drive it alone. Perfect situation for detonation or ping - still, never hear it. I've tried to force it by holding the brake and giving it some gas like works with almost any other vehicle. I could always force my Javelin to detonate if I wanted to - this, I can't.

I've had the PCM flash last fall......... they said my VIN called for it and that changed things a lot (like dropping MPG, different shifting behavior and so on, but other than that........

 

[flipmode]

Is it the same noise from my video? If so I don't think they is anything to be done. It seems more and more people are experiencing the same noise. I can easily recreate the noise while driving slowly with a gentle acceleration between 2nd and 3rd. I can make it rattle every time. I honestly have no clue what it could be and have ZERO intention on taking it to the dealer since I'm sure they will pull the same BS.

I mean its exactly like your video, and happens under the same circumstances you describe, every time. Super frustrating.

 

[DAVECS1]

Preignition or detonation? Preignition caused by hot spots before spark, detonation caused by colliding flame fronts.

Still odd that I've never heard any rattle of any sort in any of our Jeeps and truck me, when my wife is with me in our Jeeps, you end up with it shifting sooner than normal and the RPM much lower than when I drive it alone. Perfect situation for detonation or ping - still, never hear it. I've tried to force it by holding the brake and giving it some gas like works with almost any other vehicle. I could always force my Javelin to detonate if I wanted to - this, I can't.

I've had the PCM flash last fall......... they said my VIN called for it and that changed things a lot (like dropping MPG, different shifting behavior and so on, but other than that........

It is pre-ignition by high cylinder pressure. Manual trucks are more prone. My guess is valve timing was not tailored to manual operation. Auto trucks dont seem to suffer as much, but I have seen a couple of later model (2021) trucks with different valve timing that seems more prone to this. They also seem to have an emissions map that I dont have access to.

 

[Deleted member 30519]

Does it sound like this? I've been getting this rattle usually in 2nd gear on my M/T. It goes away for a while and comes back. It's worse when temps are low.

https://youtube.com/shorts/5g1xTFdpSMk?feature=share

 

[DAVECS1]

Holy cht!!!! That is the most aggressive I have ever heard it. Sure sounds like it, but that is extended and loud. I would at least get it documented at your dealer "Just in case"

 

[LoJac963]

That sounds pretty similar to mine but I have the auto

 

[DAVECS1]

I wonder if your cams are getting stuck. That sounds bad, and there yave been people with phazer issues. They can do a cleaning cycle on them, with the electronic service tool.

 

[flipmode]

I wonder if your cams are getting stuck. That sounds bad, and there yave been people with phazer issues. They can do a cleaning cycle on them, with the electronic service tool.

I will specifically ask for this when I see them again. Does the tool have a specific name I could use when telling them? I am determined to get to the bottom of this.

 

[DAVECS1]

It os jist the Chrysler service tool they plug in to update software and what not. The 3.6L has a phazer clean in the tools menu. Should take about 15 minites in the hands of a guy that knows what he is doing. I would perform it on a fresh oil change

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