Diagnose this engine tick/rattle, I paypal you 5$!

Bonanza

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I've recently been noticing a very annoying ticking/rattling/knocking/tapping sound coming from my engine area. It's become more noticeable when it's cold, and seems to sometimes mitigate as the engine warms up, or if it's warmer outside. It is not any trim pieces from what I can tell. I can only best describe the sound as that old school telegraph machine relaying a morse code-- completely irregular, but in quick succession and constant. If you tap a single finger quickly on your desk, repeatedly and consistently, it sounds quite like that.

The sound is most present in "drive", with a foot on the brake. Shifting into park, nuetral, and reverse either completely eliminates it, or reduces the volume of the tapping by about 90%. I'm on my third vehicle with this pentastar engine, and this is not the usual noisy chatter the engine makes at idle. It's definitely not as intended. My guess is a loose rocker arm. My only hesitation is that because it goes away by shifting into a different gear, the sound might be coming from somewhere else.

S0-- if it's something not inside the engine, and you help me diagnose it, I'll paypal you some money! Any suggestions?

:)





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Renegade

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I'm not interested in your money, but am willing to help. Can you have someone move the Jeep in and out of park/drive, while you attempt to pinpoint the location of the "tap"? An empty paper towel roll put up to your ear (or an actual mechanic's stethoscope) may help you do this. Once the location is narrowed, diagnosis might be easier. I am familiar with the rocker arm tap, having repaired that on each of my two previous JKs. If that's what it turns out to be, fix it quickly. It's easy, but can damage your cam lobes if left unchecked. It's actually worn out roller bearings, and not them just being "loose".
 

ShadowsPapa

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LOL
Could be anything from a shield rattle to something engine related. Awfully hard not being there. A lot of stuff will be thrown at the wall to see what sticks. It will be like a poll to see who gets the right date and time for the ice to be out of Lake Michigan in a way.
Common sense - you need TWO people.
One to recreate the sound, the other to trace down the origin, and it may include someone looking or leaning to the underside of the truck.
Loose rocker won't be impacted by gear - or shouldn't in most cases. (although that changes RPM and the PCM's reaction)
Think about it this way - "what changes" "what's different" between the sound being there or not being there.
And if in gear it's not, out of gear it is - what happens in gear that could change it? Engine torque against mounts, engine shifts a tad, things move closer together or farther apart under load.
I've seen rattles be loose flex plates, torque converter being loose on the flex plate, cracked flex plate, exhaust hanger, exhaust shield touching a pipe, pipe touching something under the truck, and a half dozen other things. And sounds transmit through the connected parts. A rattle at the back can be transmitted through the exhaust pipes so it sounds like it's up front.
Funny thing - a lot of people say the 3.6 is noisy, to me it's a quiet engine. We've had the 3.6 in at least one vehicle ever since they came out in the Grand Cherokee. In 2020, we had three of them, 2 in Grand Cherokees and the one in my JT - all very quiet engines. No unusual sounds at all. Not as quiet as the V8 in a 1975 full-sized Mercury or Lincoln with stock exhaust, but among engines in the last 40 years, pretty darned quiet. Other than the feel of the torque letting loose in my wife's GC when the ESS shuts the engine off, then restarts it, you don't really notice the lack of engine sound, or it being present again. Even with my JT - it's almost TOO quiet for me. I like to hear them a bit.
 
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Bonanza

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I'm not interested in your money, but am willing to help. Can you have someone move the Jeep in and out of park/drive, while you attempt to pinpoint the location of the "tap"? An empty paper towel roll put up to your ear (or an actual mechanic's stethoscope) may help you do this. Once the location is narrowed, diagnosis might be easier. I am familiar with the rocker arm tap, having repaired that on each of my two previous JKs. If that's what it turns out to be, fix it quickly. It's easy, but can damage your cam lobes if left unchecked. It's actually worn out roller bearings, and not them just being "loose".
Im at 4,800 miles so I’m dropping it off at the dealer as I’m also due for an oil change. I wish I had time to recruit help but I’m trying to fix the issue ASAP before King of the Hammers. I still like to post the information here for future users who encounter the same issue.

thanks for the help!! :)
 

ShadowsPapa

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Im at 4,800 miles so I’m dropping it off at the dealer as I’m also due for an oil change. I wish I had time to recruit help but I’m trying to fix the issue ASAP before King of the Hammers. I still like to post the information here for future users who encounter the same issue.

thanks for the help!! :)
The only problem is that it won't be the same issue. Rattles? Even in a JT - your case could be totally different than any other here. Many have tried to compare their rattle to another here and say "it must be the same" but that's very flawed logic!
You could have a rocker arm issue - but it could be caused by some oiling issue.......... or it could be something totally different. Trying to diagnose anything by comparing on a forum is problematic at best.
Hey, I have that issue too! I'll have them replace my xxxxx to fix it - don't go there.
SOMETIMES it works "leaking back window in the hard top", normally same cause, same solution, and I could name other things, but rattles?
Best you can do is add it to the list of possible rattle causes.
 
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Bonanza

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LOL
Could be anything from a shield rattle to something engine related. Awfully hard not being there. A lot of stuff will be thrown at the wall to see what sticks. It will be like a poll to see who gets the right date and time for the ice to be out of Lake Michigan in a way.
Common sense - you need TWO people.
One to recreate the sound, the other to trace down the origin, and it may include someone looking or leaning to the underside of the truck.
Loose rocker won't be impacted by gear - or shouldn't in most cases. (although that changes RPM and the PCM's reaction)
Think about it this way - "what changes" "what's different" between the sound being there or not being there.
And if in gear it's not, out of gear it is - what happens in gear that could change it? Engine torque against mounts, engine shifts a tad, things move closer together or farther apart under load.
I've seen rattles be loose flex plates, torque converter being loose on the flex plate, cracked flex plate, exhaust hanger, exhaust shield touching a pipe, pipe touching something under the truck, and a half dozen other things. And sounds transmit through the connected parts. A rattle at the back can be transmitted through the exhaust pipes so it sounds like it's up front.
Funny thing - a lot of people say the 3.6 is noisy, to me it's a quiet engine. We've had the 3.6 in at least one vehicle ever since they came out in the Grand Cherokee. In 2020, we had three of them, 2 in Grand Cherokees and the one in my JT - all very quiet engines. No unusual sounds at all. Not as quiet as the V8 in a 1975 full-sized Mercury or Lincoln with stock exhaust, but among engines in the last 40 years, pretty darned quiet. Other than the feel of the torque letting loose in my wife's GC when the ESS shuts the engine off, then restarts it, you don't really notice the lack of engine sound, or it being present again. Even with my JT - it's almost TOO quiet for me. I like to hear them a bit.
My guess too was that it was outside of the engine itself initially. But I couldn’t be confident because operating temp made it diminish somewhat. I changed my wife's motor mounts on her 2014 Cherokee with a similar situation-- in that it vibrated tremendously in reverse only, but then stopped in another gear. On mine, some days I can feel a slight vibration in the wheel, other days just the audible tap tap tappppp tapp tapp tap tap. I'm trying to think what can come loose, but opening the hood, the sound seemed like it was coming directly from inside the engine. It's a toughy.
 

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Im at 4,800 miles so I’m dropping it off at the dealer as I’m also due for an oil change. I wish I had time to recruit help but I’m trying to fix the issue ASAP before King of the Hammers. I still like to post the information here for future users who encounter the same issue.

thanks for the help!! :)
So you wanted us to give you “the” answer, but you don’t want to put any work into diagnosis? Ok, give me that $5 for my answer- It was correct, but I’m not going to post it. Seriously, good luck, and post back what your dealer finds...for future reference.
 
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Bonanza

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So you wanted us to give you “the” answer, but you don’t want to put any work into diagnosis? Ok, give me that $5 for my answer- It was correct, but I’m not going to post it. Seriously, good luck, and post back what your dealer finds...for future reference.
For sure! I'm going to poke around briefly before I go to inspect for obvious external issues, but don't have time to take the intake manifold off to go exploring. Might as well use the warranty! The hope, however glim, was that this might have been a common issue from a common failpoint. I didn't expect as much as this is my third pentastar, but your never know. If anything someone, someday, will search for the same issue and this thread might be of some help. :)
 

ShadowsPapa

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My guess too was that it was outside of the engine itself initially. But I couldn’t be confident because operating temp made it diminish somewhat. I changed my wife's motor mounts on her 2014 Cherokee with a similar situation-- in that it vibrated tremendously in reverse only, but then stopped in another gear. On mine, some days I can feel a slight vibration in the wheel, other days just the audible tap tap tappppp tapp tapp tap tap. I'm trying to think what can come loose, but opening the hood, the sound seemed like it was coming directly from inside the engine. It's a toughy.
In the end it will be VERY interesting to see what the cause of your particular rattle ends up being. At the very least it will add to the list of "possibles".

Yeah, you hit on another possible cause when there's a noise that changes when in gear, or taken out of gear. The engine moves, even if very slightly, and engine mounts have been a known cause.

Let's hope it's a simple thing - a shield - that can be moved or shifted. Or if it's engine-related, they find it fast and fix it for good.
 

LT1Chevy210

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I noticed the EVAP purge valve ticks on mine after installing a supercharger that relocated it to the back of the engine, nearly up against the firewall. I had originally thought it was a lifter/rocker but monitoring the purge valve command, you could see the intermittent ticking line up with the valve actuating.

I cann't hear it over the engine noise with the hood open but sitting inside the Jeep, it is quite pronounced. Placing a finger on the valve, you could feel it perfectly lined up with the sound. Just something else to think about.
 
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Bonanza

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In the end it will be VERY interesting to see what the cause of your particular rattle ends up being. At the very least it will add to the list of "possibles".

Yeah, you hit on another possible cause when there's a noise that changes when in gear, or taken out of gear. The engine moves, even if very slightly, and engine mounts have been a known cause.

Let's hope it's a simple thing - a shield - that can be moved or shifted. Or if it's engine-related, they find it fast and fix it for good.
The irregular pattern, and impact from transmission gear, make me think it's outside the engine, but the sound seems like it's epicenter is the engine. I fancy myself quite good at isolating noises, but this one has me stumped for the time being. Anyway stay tuned, I'll either find it myself or the dealer will. The first correct guess still wins the prize, because why not have fun!
 
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Bonanza

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I noticed the EVAP purge valve ticks on mine after installing a supercharger that relocated it to the back of the engine, nearly up against the firewall. I had originally thought it was a lifter/rocker but monitoring the purge valve command, you could see the intermittent ticking line up with the valve actuating.

I cann't hear it over the engine noise with the hood open but sitting inside the Jeep, it is quite pronounced. Placing a finger on the valve, you could feel it perfectly lined up with the sound. Just something else to think about.
This seems very in line with my experience. Easiest to hear from the cab, challenging when the hood is open. Is the purge valve located on the EVAP canister itself? I recall it was near the battery in my old JK, because I broke it once putting in a new battery.
 
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Bonanza

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LT1Chevy210

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This seems very in line with my experience. Easiest to hear from the cab, challenging when the hood is open. Is the purge valve located on the EVAP canister itself? I recall it was near the battery in my old JK, because I broke it once putting in a new battery.
It's located on the passenger side of the intake plenum (pictured).

Screen Shot 2021-01-20 at 2.59.24 PM.png
 

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