How does pentastar head go bad? - JKowners.com : Jeep Wrangler JK Forum
 
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post #1 of 16 Old 06-19-2016, 12:45 AM Thread Starter
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How does pentastar head go bad?

When a pentastar left head goes bad, what actually happens to cause the misfire and ticking? Is it cracking between cylinders?

Does anyone have pictures of the failed part of the head?
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post #2 of 16 Old 06-19-2016, 01:06 AM
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Quote:
Originally Posted by White13JKUR View Post
When a pentastar left head goes bad, what actually happens to cause the misfire and ticking? Is it cracking between cylinders?

Does anyone have pictures of the failed part of the head?
Just had the Wife's 2014 Caravan (3.6 Pentstar) in to the dealer under warranty for failing valve lashes. When they failed, it ticked with a rise/fall with RPMs. Had to replace the lashes, both intake/exhaust cams and rockers, valve cover gasket and intake gaskets.

I haven't heard of the head itself go bad. I'm very interested in hearing what you find out.

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post #3 of 16 Old 06-19-2016, 02:09 AM Thread Starter
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Originally Posted by ndtguy View Post
Just had the Wife's 2014 Caravan (3.6 Pentstar) in to the dealer under warranty for failing valve lashes. When they failed, it ticked with a rise/fall with RPMs. Had to replace the lashes, both intake/exhaust cams and rockers, valve cover gasket and intake gaskets.

I haven't heard of the head itself go bad. I'm very interested in hearing what you find out.
All of that might be required with the head replacement (certainly the gaskets you mentioned). Did they replace your head too? Or just those parts you mention? If just those parts, did it solve the ticking problem?


The main Pentastar issue is misfire and I found the TSB.

http://www.wk2jeeps.com/tsb/tsb_wk2_0900214a.pdf

Basically you do a cylinder leak down check to confirm the misfire codes so I am going to do that to double check that every now and then. Should be super easy now on the driver side with the blower.

I still wonder what is failing in the head to cause the failure. Valve seats, valves, head gasket failing between cylinders?

edit:
what happened in your case sounds like a lifter got plugged. I have diagnosed and repaired a ton of those under warranty. I also diagnosed and repaired some of the head failures in the early 1980-1982 2.0l Mazda RWD cars. They would blow the gasket material between two cylinders and then eat away the head so bad that it had to be replaced. On a 4 cy car, you knock 2/4 of the cylinders out. Not as bad on a v6. The knock in the case of the old Mazdas occurred because the cylinders could see each through the small opening and there was a lot of pre-ignition. I wonder if our penatastars are doing that?

Last edited by White13JKUR; 06-19-2016 at 02:14 AM.
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post #4 of 16 Old 06-19-2016, 09:14 AM
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dunno if it will help but I always found useful info on my 3.8at the Allpar site for that powerplant . Chrysler Pentastar V6 Engines for 2010 and Beyond is the Pentastar pages.

There is a link there to repairs ,where this info resides (again, might be stuff you already know ) :
http://www.pentastars.com/engines/repairs.php


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post #5 of 16 Old 06-19-2016, 10:59 AM Thread Starter
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Thanks for that.

So the #2 valve seat is getting overheated and coming lose on the left head (driver's side on a left hand drive jeep). The fix is a new head with hardened valve seats. Apparently other cylinders can be affected on the same bank but the other head does not have the same problem. Sounds like they should really be replacing both heads. I'mna go ahead and do occasional leak down tests. A loose valve seat will just get worse left and is eventually going to cause catastrophic failure if it comes completely loose.


The Pentastar page goes on to talk about other subjects and goes on to say that Chrysler is the only or one of the only manufacturers still using just MAP sensors and no MAF sensor. I got a little chuckle out of that because the old Subarus I used to work on (the old "Loyale" or "L" series) used to have that option. The cheaper "SPI" (Single Point Injection) used *only* MAP sensors. It was cheaper. The more expensive NA and FI Subarus with "MPI" (Multi Point Injection) all used a hot wire MAF. The MPI cars ran stronger, of course, and were more responsive. The SPI/MAP cars were decently responsive but not quite the same.
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post #6 of 16 Old 06-19-2016, 11:01 AM
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Quote:
Originally Posted by White13JKUR View Post
All of that might be required with the head replacement (certainly the gaskets you mentioned). Did they replace your head too? Or just those parts you mention? If just those parts, did it solve the ticking problem?
Yes, it did solve the ticking issue.

One thing we noticed (because I'm OCD and keep tabs on mpg on my vehicles) was the mileage dropped 3-4mpg just before and during the ticking.

Talked to the service manager and asked if this is normal. He stated that he has seen a few, but there are a lot of 3.6 pentstars out there. Basically it's nothing to worry about statistically but it has happened. We lucked out because we just bought the van as a pre-certified, so there was no issues.

I also keep a notebook on each vehicle with all maintenance/modifications with receipts. I also take care of the oil analysis using a spectrol M/N at work.

(Talking about my JK) I noticed copper (CU) was high (47 ppm) and when I looked up other peoples oil analysis online, my number was the lowest I could find (by a long shot...iirc next lowest was low 80s). Blackstone said in the other peoples analysis that CU in the pentstar engines is always high on their analysis, regardless of the oil used. My analysis was performed with 5500 miles on the oil and all the other elements were good. I change oil around 5-5500 miles and do the 5 tire rotation.

Hope this helps.

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post #7 of 16 Old 06-19-2016, 11:20 AM Thread Starter
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CU? You mean CO? Smog check tests CO and HC among other things. CO should be near 0 I would think. WHen I used to do smogs in the early 1990's, most cars tested under 15 or so on CO (or was it HC - don't even remember anymore).

I could dial in an old rotary engine with a thermal reactor (pre catalytic converter) to near zero/zero. We are talking 1970's era cars that I was mucking with in the 1980's.
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post #8 of 16 Old 06-19-2016, 11:37 AM
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Can it be assumed that post '12 problem engines come with hardened valve seats or is it in fact?
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post #9 of 16 Old 06-19-2016, 11:38 AM
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Quote:
Originally Posted by White13JKUR View Post
CU? You mean CO? Smog check tests CO and HC among other things. CO should be near 0 I would think. WHen I used to do smogs in the early 1990's, most cars tested under 15 or so on CO (or was it HC - don't even remember anymore).

I could dial in an old rotary engine with a thermal reactor (pre catalytic converter) to near zero/zero. We are talking 1970's era cars that I was mucking with in the 1980's.
I think he is talking oil sample. Not smog test.
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post #10 of 16 Old 06-20-2016, 12:23 PM
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I was told by the mechanic at the dealership that replaced my drivers side head on my former 2012 JKU that the wrong valves were put in the heads at the factory.
He said the 3.6L requires revolving valves but the factory installed non-revolving valves by mistake. This would cause the head to fail after a period of time.
I think someone got a valve order wrong at the factory.

P.S: This is just what the mechanic told me, it doesn't mean it's true but it does make sense.
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post #11 of 16 Old 06-22-2016, 10:34 AM
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Quote:
Originally Posted by White13JKUR View Post
CU? You mean CO? Smog check tests CO and HC among other things. CO should be near 0 I would think. WHen I used to do smogs in the early 1990's, most cars tested under 15 or so on CO (or was it HC - don't even remember anymore).

I could dial in an old rotary engine with a thermal reactor (pre catalytic converter) to near zero/zero. We are talking 1970's era cars that I was mucking with in the 1980's.
Quote:
Originally Posted by Chicken Corners View Post
I think he is talking oil sample. Not smog test.

Exactly. CU = Copper

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post #12 of 16 Old 01-24-2020, 09:55 PM
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where is this copper from is the question, and can this copper be contributing to the Head Failure, I recently had my head fail on my 2012 JK. luckily it is being covered under warranty.
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post #13 of 16 Old 01-25-2020, 01:26 PM
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Copper normally comes from bearings. Not sure what else inside the pentstar engine would be made of copper.

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post #14 of 16 Old 01-25-2020, 02:46 PM
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Saw this old thread pop up, and just got my jeep back today from the dealership.
My jeep is a 2016 and has about 54,000 miles on it, and you could say it is heavily modified, after the transfer case, everything is different, axle housings modified, different axle shafts, drive shafts, steering knuckles, steering linkages, steering gear, etc. I was legitimately worried about warranty denial, because of the extensive mods.
What was done on mine was new rocker arms on the side of the number 4 cylinder, new tappets, and new cams. Also associated gaskets, etc. They tech billed out 3 hours for it.
As far as I can tell there are a couple of things. Immediately, mileage when up, according to the computer, and of course, they are absolutely reliable. Also, the ticking that has been going on forever, without a code, also stopped. We will see if both things continue,
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post #15 of 16 Old 01-27-2020, 07:07 AM Thread Starter
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From what I understand, there are a couple of things going on with the Pentastars...

1) The original problem I posted about in this thread is for the 2012 and older models having the valve seats come loose and you have to replace the entire head. Check julian date above the exhaust port etc. This sill cause a tick and throw misfire codes. There is a TSB, I believe on this and the engine warranties were extended. My 2013 is among the first to have the new heads from the factory (with new, improved? titanium valve seats).

2) The second ticking noise that I heard about is from failed rocker arms. Found this video on the subject and it shows how easy (compared to pulling the cams or head).

3) Not sure about the copper content but there is also apparently a problem with casting sand still being trapped inside of our engine blocks from the factory. Wondering if the copper content is related to that known problem.
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post #16 of 16 Old 01-27-2020, 02:56 PM
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Sand would show up on an oil analyst as silicon (SI). (I perform oil analysis with a spectrol m/n and is maintained IAW USAF requirements).

Thanks for the video on the rockers. I believe mine is developing the rocker tick. It sounds like an exhaust leak. It isn’t noticeable at idle but when you start driving between 1500-2000 rpms, especially up an incline, it is very noticeable and lasts for about 2 miles (in the morning). Maybe a 1/4 mile in the afternoon.

Wife’s grand caravan had the same issue but got bad really quickly. Dodge ended up replacing the rockers, keeper/retainers and cam that it affected.

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