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A different Pentastar issue

20K views 35 replies 18 participants last post by  Mpod 
#1 ·
I have a 2012 JKU that started running differently at about 20K miles. I now at 25K+.

Once warm the engine now vibrates at low rpm's especially at idle. It also makes a loud low frequency drone while this is happening.

This doesn't sound like a metal on metal vibration (like a heat shield). I've had that issue on other vehicles. The best I can describe this is that it sounds and feels like I'm trying to take off from a stop in 5th gear. The engine sounds like it's bogging down.

This used to happen only once in a while and below 1200 rpm's. Now it happens with every drive and up to ~2500 rpm's. It happens with AC on and off but does vibrate a little more with AC on.

For the first 20K miles, she ran like a champ and idled smooth as butter. I want that Jeep back...

I tried using a fuel injector cleaner which actually seemed to work for about half a tank. Also tried seafoam with no change. I've also filled up at several different gas stations in case that was the problem. No change.

I've been to the dealer twice and the service manager says it's normal and since I'm not throwing a code, nothing is wrong. The second time I brought it in, it was vibrating and making the loud drone sound and he acted like he couldn't hear or feel it. The harmonics were so loud at that time that we both had to raise our voice to talk. Needless to say, I'm done with them and may need to try another dealer. Thought I would check with you guys first.

Any ideas?
 
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#3 ·
Have you been out playing in the mud? The sound/feeling you describe I have seen before when mud or sometimes ice gets packed up between the frame and engine/transmission. It's amazing how motor mounts isolate the harshness and vibration of an engine but if there is even just a minor connection between those components and the chassis/body it creates some loud noises. Look for anything like that. I see it a few times a year as a technician.
 
#7 ·
that is a strange one, I would suggest a compression test. I has a Liberty that had very similiar issues and I had to have a cylinder replaced. The noise, vibration, inconsistency and the poorer mileage are all what I experienced. It may not be this at all but it took me 10 months and countless appointments before we ran the compression test and found the issue.
 
#8 ·
I disconnected battery for a few minutes and the shaking/humming started right away after turning engine on. I was really hoping it would be this simple...

I haven't done any mudding but went ahead and checked the motor mounts. All clear and clean.

I crawled under the jeep while the motor was running to see if anything was physically rubbing/vibrating. It sounded like someone was running a manual typewriter under there. Pretty sure I have the infamous ticking but no codes thrown yet. I can hear it from above too but it's much louder underneath.

That said, I've read a lot of the ticking pentastar posts but haven't noticed that others have had my symptoms.

I may have to see if another dealer would be willing to do the compression check without a code.

Thanks for the ideas, keep em coming!
 
#12 ·
. . . It sounded like someone was running a manual typewriter under there.. . .
Thanks for the ideas, keep em coming!
Is the clicking noise irregular (like a typewriter) or in sync with the revs?
It wouldn't be ticking valves at the bottom of the motor.

You haven't said if it's an auto or manual but if it's an auto then it could be related to a problem with the torque converter or valve body operating incorrectly.
 
#11 ·
I have a 2012 JKU that just hit 17,000 miles with the same problem. It started last week and has been getting progressively worse. I first noticed at a red light but didn't want to admit I was feeling vibrations. Today it is undeniably vibrating/idling rough. I have not experienced the drone though... I have noticed it is not as bad with the AC off and once I get it in motion it's working like it should. Have not had a chance to take it back to the dealer, nor do I want to. I gave up on my dealers service department after I took it in the 4th time for leaks :/ Please keep us posted and good luck with your Wrangler.
 
#13 ·
clicking noise is consistant and seems to be synced with rpm's. I can't tell for sure where the source of the noise is. I can definitely hear it more clearly under and behind the engine but that could be because there is less background noise down there (cooling fan, road noise, etc).

I have an automatic. Would the torque converter cause rough idle while parked or only while underway at low rpms? I'm having vibrations/low frequency harmonic drone (like a subwoofer humming) in both cases.
 
#16 ·
This is a strange one... I'd swear based on some of the symptoms (vibration/poor mileage) that you had a head issue, but the others are kind of weird.

The best case scenario from your description would be a bad catalytic converter. The cores come loose and plug the exhaust, which would definitely cover the loss of power and weird sound. A broken cat core is usually accompanied by a very distinct rattle.

Definitely want to read suggestions and find out the resolution on this one. Good luck!
 
#19 ·
A broken cat core is usually accompanied by a very distinct rattle.

Definitely no metal on metal type of rattle. I had exhaust system vibrations on a 2000 Xterra and I know the sound your talking about. I followed the exhaust to the tailpipe on the Wrangler and couldn't see or hear anything unusual.

The low frequency drone can really only be heard from inside the cab. I think it's the engine vibration hitting just the right frequency to cause reverberation when at idle. ~600-800 rpm seems to be the sweet spot for the drone although the vibration itself continues evenly through about 1500 rpms and then starts to fade and finally goes away at about 2500 rpms..
 
#21 ·
Status Update:

Took her to dealership #2 on Saturday and had one of the service desk guys sit inside so he could feel and hear what was going on. He agreed it was not normal. -PROGRESS.

Work was scheduled for Monday so at the end of the day I called to see how things were going. This time a different service manager. He said they test drove it and scanned for codes and she passed with flying colors. "The ticking sound is normal lifter noise". "Nothing wrong with your Jeep".

I explained that one of their other service managers agreed that the engine was vibrating and droning and that it was not a normal idle. He said they hadn't finished the recall work anyway so they would look at it some more on Tuesday.

So Tuesday (today), I drove by after work to see what was going on. More scanning, more test driving, but all is normal and if anything whatsoever was wrong, the computer would throw a Pending code.

At this point I was less then happy and made it clear that something is wrong with my Jeep and if anyone drove it for more than a few minutes they would know that. He offered to have one of their QA guys ride with me. Turns out it was the shop foreman. I agreed and off we went.

Sure enough, after 5 minutes of driving around she starts vibrating and humming like a tuba. He said he would go grab one of his mechanics to show him what was going on but he thinks it may have something to do with the motor mounts. The good news is that they finally agreed that something is wrong and they need to go figure it out.

Baby steps...
 
#22 ·
It sucks when they can't trouble shoot something and rely on it throwing a code. A bad motor mount isn't going to throw a code. I miss the good old days when a good mechanic new how to trouble shoot a vehicle. If you find a dealership that has a tech like that he's the guy you want working on your Jeep.

As far as your Jeep goes I have a feeling its more than a bad motor mount. Your mpgs wouldn't take a big hit because of a bad motor mount. Best of luck to you with getting your problem resolved. Hopefully its something simple.
 
#25 ·
They seem to have a problem properly refilling them, I've heard and read lot of people complaining about that. Keep an eye on the level in the radiator too for a few days. Check it when cold, first thing in the morning on level ground, top up the tank and radiator as needed. Don't go over the full cold mark, and use a 50/50 mix of the Chrysler approved coolant. When the radiator is filled to the top, and the coolant expansion tank is dead on the full cold mark for a few days of driving, it is safe to a$$ume you have no leaks and no air. You may have to check and tweak as I mentioned a few times to get it right. Too bad they don't take the time to bleed it right, and make sure it leaves problem free. But in all fairness I've had friends replace heater cores, radiators, etc. by repair shops and run into the same problems.
 
#26 ·
Day 3. They checked the motor mounts by lifting my jeep next to a new one and comparing the two. Motor mounts looked fine so they ordered transmission mounts.

They still claim that it would throw a code if it was a motor problem. I'm not sure how mounts cause an mpg drop and rough idle only when at normal operating temp. Now we wait for parts and see what happens.
 
#27 ·
Well, they say "TIMING" is everything. I am a recent owner of my very first, brand new vehicle. A 2014 JKRU. The dealership that was able to meet my price requirement and sold me the Heep, called me today to see if I was happy with them regarding my new vehicle. I told them I was extremely happy, but had a question as to required services to avoid voiding warranties. The service manage called me back about 15 minutes later. Because we are a very small community, in my hour long conversation with him, we found out that he went to school with my wife and I went to school with his older sister. We know all the same people around town and have a LOT in common. After we established that rapport, he told me of a "KNOWN PROBLEM" they have been dealing with ever since the 3.6 engine came out. There is a valve guide problem that requires the replacement of one of the heads. It's symptoms are exactly what you are describing. He also said when it gets bad enough, it will trigger a error code. It tells of a miss in 1 or 2 of the cylinders. He never told me which side, just one of the banks. He informed me that in the new 2014's, this problem should not manifest as they are replacing the defective head at the factory. BUT, to me, that sounds like what you are experiencing at it's early stages.

Call the Yucca Valley (Ca.) Chrysler Dealer 760-365-2353 or 760-228-1818 and ask for the service manager with the last name "Middleton." I can't remember his first name as I went to school with his older sister. He may have let the cat out of the bag but he said it is a KNOWN PROBLEM..... LUCK!!!
 
#28 ·
Got her back last night. Went for a 25 mile test drive early this morning and no more vibration or droning sounds. My wife and I can't ever remember the Jeep idling this quietly or running this smooth before. Must have been the transmission carrier.

I reset the mpg indicator before the test drive and averaged 18.5 with 50/50 city/highway. Makes no sense to me that the mpg drop could have had anything to do with a mount unless the motor was losing power transfer efficiency from all the vibrating? I'll keep an eye on the mileage. It may just be too small of a sample to read anything into it.

I still think she's ticking although the dealership claims it is normal lifter ticking. I may have to record it and post to see what you guys that have had the bad head think about the noise.

Regardless, for now I'm just glad that she's running smooth. I can finally enjoy driving my Jeep again.
 
#34 ·
So transmission mounts?



Hi, so was it the transmission mounts that fixed the issue for you? I'm experiencing something very similar right now, I just got the jeep back after being in a minor accident... I drove it for 3 days and noticed a weird vibration between 1 and 1.5 RPS. I sent the jeep back in and they found something they missed the first time... a hole in my catalytic converter and a bad engine mount...both from the accident... so they replaced both and I just got the jeep back for the 2nd time last night but the vibration did not go away at all... if anything it's worse. Its very noticeable anytime between 1 and 1.5 and sometimes at idle. It's vibrating so much its driving me nuts and putting my leg and back to sleep when I'm sitting there idling. I'm calling my insurance co. tomorrow to let them know its still an issue but looking for ideas on what it could be. Sounds like for you it was the Transmission mounts correct? Maybe I can specifically have them check those since it sounds very familiar.
 
#31 ·
Your head will not get replaced unless you throw a code and the dealership does a leak down test. This all have to have pictures and in some cases video for chrysler to warranty it. I just had my head down and B&^%$ed a fit to get it done. I explained to them that good engineering practices is not to wait to failure but at the initial symptom. I also contacted Chrysler corporate and had the area manager get involved. It has been since July and they finally agreed to fix it last week.

The squeaky wheel gets the oil!
 
#32 ·
IMO - the new world of Internet Forums has both saved our bacon as consumers and fried the bacon of many many businesses that choose to operate in a less than ethical and forthright manner.
The "Good" ones were/are fine either way.
A Good dealership service department would acknowledge a problem not even attempting to explain away the obvious as "normal".
They would then take a certified mechanic (with stethoscope if needed) and verify the source of the noise unless it was just plain obvious where and what the problem was, not always so easy these days with the engine complexity.
Thank God for Forums and group awareness/communication.
 
#35 ·
2013 JK 24K miles with the same symptoms. I was rear ended but I believe the vibration was there before though it was more noticeable afterwards. The dealership said they inspected the motor and transmission mounts and were adamant they weren't the problem. I found this discussion and others that seemed to point to the trans mount. This was heat sensitive as in it would do it right of way on a hot day or after about 30 minutes in traffic so it' seemed to point to something soft and more susceptible to even relatively minor heat variances. I mentioned the forum suggestion to the tech and he said there's too many people who think they are mechanics on them and dismissed the trans mount. They got Chrysler involved and were ready to pull the transmission apart when I refused to let them before they tried the trans mount. After three weeks of poor communication and ridiculous ideas my jeep is smooth as ever after a trans mount replacement. I'm now looking for a new dealership to provide service. No codes, idle vibration that goes away increasing RPM and heat sensitive...consider replacing the trans mount. There's a couple of other discussion that indicate a problem without a collision but it's probably more suspect after a fore-aft collision.
 
#36 ·
Skierx, Sorry for the late reply but I didn't see your post until today. Yes it was the transmission carrier that was causing my vibration/drone problem. The carrier itself had to be replaced. It wasn't an issue of loose bolts.

My original dealer ignored it altogether. Drone? What drone? Drove me nuts. The shop foreman of dealership #2 figured it out after running two jeeps side by side on lifts and comparing all drivetrain touchpoints. The vibration has never returned.
 
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