Jeep Wrangler Forum banner

1 - 10 of 10 Posts

·
Premium Member
Joined
·
209 Posts
Discussion Starter #1
I've had my 2015 JKU with automatic transmission just over 2 years. Sometime within the past 6-8 months it's developed a vibration at idle. I'm looking for ideas on things I can check and how to check them, because I don't have much wrenching experience.

It's still under warranty as I only have 20k miles on it, but I'm hoping to get this figured out before my appointment Tuesday, Sept 5th at the dealership. You know how it goes at the dealership... "we can't reproduce it... it's caused by your lift... blah, blah".

Details:
1. The vibration is mostly a very low frequency hum and it only occurs at idle speed of 700 rpm. At its worst, it can make your ears hurt if the windows are closed.
2. I feel a very slight vibration in the steering wheel, but it also affects the dash. I keep change in that small area right in front of the shifter, and it also rattles a little bit while this is happening.
3. It occurs about 90% of the time when the engine is at idle and in gear, either drive or reverse. Like at red lights or stop signs.
4. It occurs about 50% of the time when the engine is at idle but in park or neutral. But there are definitely some times when shifting from drive to neutral (or park) makes it stop temporarily until I go back to drive.
5. I opened the hood with the engine running and had my wife put it in gear a few times and I don't hear the vibration in the engine compartment. It's only inside the Jeep that you hear it.

I looked briefly at the transmission mounts while under the Jeep and did not notice anything wrong. What other things should I be looking for? Could the exhaust pipes be causing it? Oil is Penzoil full synthetic 5w20 in case that is relevant.

Thanks,
Russ
 

·
Registered
Joined
·
1,482 Posts
What you are likely experiencing is some type of resonance. Just the right frequency and just the right everything else that you get an amplification of certain waves, which is a loop that creates even more. Death-wobble is a type of resonance as well... Most exhaust systems will have pressure levels that are resonant... Wheel balance showing itself at 55mph is the same idea.

It is something mechanical, but it doesn't necessarily mean something is broken (but it could be). These resonant ranges exist in everything, and we just don't notice them unless it is persistent and louder than the other noise. The 3.6 isn't a very smooth running motor. Say one of the balance shafts isn't just right, they replace it, and now instead of a resonance at 700rpm it's at 720rpm. It isn't gone, but it's gone from where it bothers you.

The large, flat metal panels of the Wrangler don't help. They can greatly increase resonance. Pulling panels and using Dynomat (or similar) can make huge improvements in Wrangler noise as they have very little insulation.

The fact you only hear it inside really makes me think you are looking at an unlucky resonance situation. Every vehicle has it to some degree... Have you done anything with the intake? Most people don't realize as much racket comes out the front end of the system as the back...
 

·
Premium Member
Joined
·
209 Posts
Discussion Starter #3
Have you done anything with the intake? Most people don't realize as much racket comes out the front end of the system as the back...
Thanks for the reply. You could be right about it having a resonant frequency at 700 RPM. When I give it just a tiny bit of gas and the RPM goes up to 800-900 the noise goes away. I'll investigate options like the insulation you referenced. Perhaps there's a way to just slightly raise the idle rpm.

To answer your question, no, I have not modified the intake. Nothing in the engine bay has been changed other than some wiring for cube lights and winch.

-Russ
 

·
WF approved Offical Jeep Account.
Joined
·
1,494 Posts
I've had my 2015 JKU with automatic transmission just over 2 years. Sometime within the past 6-8 months it's developed a vibration at idle. I'm looking for ideas on things I can check and how to check them, because I don't have much wrenching experience.

It's still under warranty as I only have 20k miles on it, but I'm hoping to get this figured out before my appointment Tuesday, Sept 5th at the dealership. You know how it goes at the dealership... "we can't reproduce it... it's caused by your lift... blah, blah".

Details:
1. The vibration is mostly a very low frequency hum and it only occurs at idle speed of 700 rpm. At its worst, it can make your ears hurt if the windows are closed.
2. I feel a very slight vibration in the steering wheel, but it also affects the dash. I keep change in that small area right in front of the shifter, and it also rattles a little bit while this is happening.
3. It occurs about 90% of the time when the engine is at idle and in gear, either drive or reverse. Like at red lights or stop signs.
4. It occurs about 50% of the time when the engine is at idle but in park or neutral. But there are definitely some times when shifting from drive to neutral (or park) makes it stop temporarily until I go back to drive.
5. I opened the hood with the engine running and had my wife put it in gear a few times and I don't hear the vibration in the engine compartment. It's only inside the Jeep that you hear it.

I looked briefly at the transmission mounts while under the Jeep and did not notice anything wrong. What other things should I be looking for? Could the exhaust pipes be causing it? Oil is Penzoil full synthetic 5w20 in case that is relevant.

Thanks,
Russ
Hi Russ,

Sorry to hear about this! Don't hesitate to send us a PM with any questions or concerns that may arise during your dealership appointment, we're happy to assist if needed.

Andrea
Jeep Social Care Specialist
 

·
Registered
Joined
·
965 Posts
I've had my 2015 JKU with automatic transmission just over 2 years. Sometime within the past 6-8 months it's developed a vibration at idle. I'm looking for ideas on things I can check and how to check them, because I don't have much wrenching experience.

It's still under warranty as I only have 20k miles on it, but I'm hoping to get this figured out before my appointment Tuesday, Sept 5th at the dealership. You know how it goes at the dealership... "we can't reproduce it... it's caused by your lift... blah, blah".

Details:
1. The vibration is mostly a very low frequency hum and it only occurs at idle speed of 700 rpm. At its worst, it can make your ears hurt if the windows are closed.
2. I feel a very slight vibration in the steering wheel, but it also affects the dash. I keep change in that small area right in front of the shifter, and it also rattles a little bit while this is happening.
3. It occurs about 90% of the time when the engine is at idle and in gear, either drive or reverse. Like at red lights or stop signs.
4. It occurs about 50% of the time when the engine is at idle but in park or neutral. But there are definitely some times when shifting from drive to neutral (or park) makes it stop temporarily until I go back to drive.
5. I opened the hood with the engine running and had my wife put it in gear a few times and I don't hear the vibration in the engine compartment. It's only inside the Jeep that you hear it.

I looked briefly at the transmission mounts while under the Jeep and did not notice anything wrong. What other things should I be looking for? Could the exhaust pipes be causing it? Oil is Penzoil full synthetic 5w20 in case that is relevant.

Thanks,
Russ
HI Russ, did you fid a fix?
My 2018 is humming at idle in gear since day one. Its mostly noticeable at redlight in traffic. Thought it would go away after break in but it didn't.
It get worst with the AC on and goes away in N or Park.

Checked under the jeep for lose bolts or shields, checked the trans mount - everything looks good.
Since the noise is low frequency can not locate the exact place is emitted from.
Any input appreciated,
Thx
 

·
Premium Member
Joined
·
209 Posts
Discussion Starter #6
HI Russ, did you fid a fix?
My 2018 is humming at idle in gear since day one. Its mostly noticeable at redlight in traffic. Thought it would go away after break in but it didn't.
It get worst with the AC on and goes away in N or Park.

Checked under the jeep for lose bolts or shields, checked the trans mount - everything looks good.
Since the noise is low frequency can not locate the exact place is emitted from.
Any input appreciated,
Thx
No, I never figured it out. I installed some noise dampening material under the carpets, and that helped a small amount. I checked all the same things you did. I gave up on it. My ears kinda automatically block it out by now. Good luck. I hope you have better results troubleshooting.
 

·
Registered
Joined
·
4 Posts
My 2018 JKU Recon had a similar vibration after I got it back from the Dealership. They replaced the transmission valve body and performed a oil change. This has been bugging me ever since but I don't drive it a lot. Well today this vibration was happening every time. I found that I could be a traffice light, leave in drive, and set the parking break. The vibration was present. So when I pulled into the Walmart parking lot it was doing it. I left it in drive set the parking brake and started looking around. Under the dash and outside. Popped the hood and started looking around. We I found that the engine cover was loose. The dealership didn't even try to put it on properly, it was just laying on the engine and looked like it was secured. I secured it and so far no more vibrations. May not fix your vibration but something to look at.
 

·
Premium Member
Joined
·
209 Posts
Discussion Starter #8
My 2018 JKU Recon had a similar vibration after I got it back from the Dealership. They replaced the transmission valve body and performed a oil change. This has been bugging me ever since but I don't drive it a lot. Well today this vibration was happening every time. I found that I could be a traffice light, leave in drive, and set the parking break. The vibration was present. So when I pulled into the Walmart parking lot it was doing it. I left it in drive set the parking brake and started looking around. Under the dash and outside. Popped the hood and started looking around. We I found that the engine cover was loose. The dealership didn't even try to put it on properly, it was just laying on the engine and looked like it was secured. I secured it and so far no more vibrations. May not fix your vibration but something to look at.
That's interesting. I know for sure mine is on tight, because I change my own oil and always make sure it's secure. But it still could be the noise source and would be easy to test. I think I'll just pull it off and go for a ride tomorrow. I never checked anything related to that cover. Thanks for posting.
 

·
Registered
Joined
·
899 Posts
I have the same issue - put it in N when it gets bad and it stops. Happens mostly at red lights.

As others mentioned, it’s a simple resonance.

I’ve learned to ignore it.
 

·
Registered
Joined
·
965 Posts
Update: I kept searching for the hum source that i had mostly at red lights (D+brake) and couldn't found anything outside of the cabin. Yes, the exhaust is humming at idle but still the hum is more noticeable inside of the cabin. In my case the hum from the exhaust is amplified by the hardtop.
The hardtop (mostly rear part) is working as a huge resonator.
Removed the freedom panels, loaded the back of the hardtop with some 5 qrt oil jugs and voila no more hum or at list not that noticeable inside.
 
1 - 10 of 10 Posts
Top