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V6 Cylinder Head Failure

31K views 45 replies 19 participants last post by  padgett 
#1 ·
What is causing V6 cylinder head failures? Is there a fix? What model/year vehicles are affected? Is it a carbon buildup problem? Would usage of sea foam fuel injector cleaner help? Would hotter spark plugs help? Would synthetic oil help? Is there going to be a recall/service bulletin?
 
#4 · (Edited)
The only offficial announcement was in mid-August and did not say much. There have been a lot of posts but no real information.

Until there is either an offical revelation or a TSB (and am surprised there hasn't been one), we are just guessing.

That said what we know is that:
1) Usually affect #2 and sometimes #4 cyl
2) Is characterized by misfires in #2 and #4 cyl (most scan tool programs can display, is part of test #06). Codes P0300, P0302, and/or P0304 may be set
3) Valve guide damage has been mentioned - would explain need to replace head.
4) Manufacturing error has been mentioned but would not explain 3-4 different part numbers for driver's side head
5) Comments in posts could be consistant with hot/lean detonation. However it was said that heat was not a factor
6) "Betts said the problem has been found in about half of 1 percent, or about 7,500 of the about 1.5 million Pentastar engines" - Autoweek.
7) Most have been in Wranglers though other instances (WK2) have been seen. All of the car lines mentioned are large, heavy vehicles.

Bottom line: CJF has not said anything since August though with a return of cool weather the incidence seems to have dropped off.

We need either someone who would understand to examine both a failed and a new head or for CJF to issue a TSB.

ps found a reference that a valve seat was found to be "oblonged". This would be consistant with a valve guide problem and cause a leakdown test to be low.

See also Update on ticking Pentastar..new head... - Page 116 - Jeep Wrangler Forum post #3453.
 
#5 · (Edited)
Autoweek article is good. I would differ with company that cause of cylinder head failure (low quality fuel/driving conditions/exhaust routing) is not associated with a design problem. Their fix in new cars apparently is to adjust design.
A lot of us have to live with the fear that our engines have a reliability degrade and may not last as long as they should. This issue may be degrading other parts of the engine. I smell in the low quality fuel issue ethanol & winter/summer grades.
At the minimum company should provide lifetime engine warranty, monetary compensation and issue bulletin of fuels & driving conditions to avoid. Would fuel additive help? Would premium fuel help? Can this exhaust routing be fixed?
 
#6 ·
Head failure was a mfg./quality issue NOT a design issue. It only affected early build engines and its very very limited in scope. As mentioned above you get a cel generally associated with a misfire. Replace with the new heads and problems goes away permanently. Doesn't cause any adverse issues with the durability of the engine.
 
#10 ·
Head failure was a mfg./quality issue NOT a design issue. It only affected early build engines and its very very limited in scope. As mentioned above you get a cel generally associated with a misfire. Replace with the new heads and problems goes away permanently. Doesn't cause any adverse issues with the durability of the engine.

This is not correct. If anything it seems early builds did not have this problem as much. If you read these boards it seems its a lot more common on the 2012 models.
 
#7 ·
my wifes 2011 durango recently threw a check engine for the #5 cylinder . First time the dealer replaced an injector. Pissed me off and wasted my time. It went about a week and threw the same code. Just got it back last friday after the head replacement.
 
#8 · (Edited)
Interesting, first I've heard of a passenger side (1,3,5) head giving the problem.

"Head failure was a mfg./quality issue NOT a design issue." - might I ask what you base that on ? I have not seen any information released on the source of problem.

Also "It only affected early build engines" - thought it peaked so far with 2012 MY vehicles. Do you know something different ?
 
#11 · (Edited)
Didn't it just become available with the Wrangler in 2012 ? Maybe that is the reference.

Does seem more prevalent in Wranglers, major difference is that most Pentastar WK2s have a 3.09 axle and wranglers seems to have s 3.73 so turns higher on highway.

Gasoline has been mentioned. Would think E-10 might run cooler than pure reqular, latent heat of vaporization of regular is around 150 btu/lb and ethanol is 396 btu/lb. Wonder what % of failures were on pure gasoline.

Something else I have seen mentioned but no corroberation is that US built engines are more likely to have the issue than Mexican (on window sticker).

Finally and one of the few statisics I have seen is .5% of 1.2 million Pentastars. What I have not seen is a breakdown by car line & suspect those over 4000 lbs are at most risk. If so the % of those may be much higher.


So after several thousand warrenty repairs, CJF must know a lot about which vehicle lines and engine builds are most affected. That is is not being released is significant in itself.
 
#16 ·
believe what you would like. The AA heads were the issue the AC corrected it. There were no design changes.

Let me be clear here because you don't seem to understand. They started using the AC head in July 2012 this is ENGINE build date not vehicle build, so in July 2012 they started using the AC heads in engine production. That is why some early 2013's still had the AA heads. This was after a brief period of using the AB heads. An engine built in May or June of 2012 or anytime in 2012 for that matter is NOT an early build. An early build would be May of 2010. I also never said it was a design change they have not said what it was. All we know is the part number changed which is supposed to correct the problem. Maybe since you have all this first hand knowledge you could tell us what it was.
 
#17 · (Edited)
So anything prior to June 2012 is considered "early" and probably has the AA head ?

Part of my problem is the difficulty of seeing the head number on my Oct Build 2012 WK2 but suspect it s an AA.

What I do not understand is what kind of difference between the AA and AC heads would not be a "design change". Do you know what the difference is between an AA and an AC ?

Or does "design change" have a special meaning in CJF? I would consider a difference in machining or tolerance to a casting to be a "design change". Definition please.
 
#20 · (Edited)
Well our 2011 Grand Cherokee has 35,500 miles and the other day it started missing so badly that is would barely stay running. I started it the next day and it appeared to be missing on one cylinder then within a minute of me moving it so the tow truck could get it, it started missing on at least 2 cylinders. The dealer told my wife it was missing on all 6 cylinders? They ended up draining the gas and putting in new and said it was still missing on one cylinder and that it needed a new head. It was supposed to be done today, but the said both heads were bad. They said they have seen this on Grand Caravans, but this is the first GC. They told her it is being caused by carbon build up issues. While I seriously doubt either head was bad and this dealer is just throwing parts at it, there definitely is some sort of design or machining spec issue with these heads. If you search ( I Own a 2012 JK so I have been reading a lot on the wrangler forums of failures ) there are reported problems on every vehicle Chrysler sells with this engine. If the 2 new heads fix our GC (which again seems highly unlikely based on zero symptoms prior), I will seriously have lost any confidence I have in this engine and unfortunately for me both of my vehicles have the 3.6

UPDATE: Ok just got it back yesterday. They replaced both heads, one side is part # ending in 'AC' other is ending in 'AD' , the problem is gone. They repair order said "code P0304 cyl 4 misfire and P0300 multiple misfire, found that intake valves on both heads were sticking open."

It seems most people have a noisy head or on again off again check engine lights or misfiring. Ours just starting missing out of the blue so bad it would barely run....go figure
 
#25 ·
If you search ( I Own a 2012 JK so I have been reading a lot on the wrangler forums of failures ) there are reported problems on every vehicle Chrysler sells with this engine.
This is totally false...not even close. The last I read, the problem affects ~0.5% of Pentastars on the road. It's statements like this that give us a (false) bad name. There are over 1.5 million Pentastars on the road. The problem has affected around 7500 of them as of August (latest data). Believe what you may, and Chrysler may be "padding" the numbers, but not every Pentastar is affected...not even close to 10%.
 
#21 · (Edited)
While my GC. Is currently in the shop to check for the ticking sound and reason for the CEL I found some information about it. Not sure if it has been posted already in one of the other thousand threads with the V6 head issue;


Case Number: S1209000022
Release Date: 10/16/2012
Symptom/Vehicle Issue: Identifying Service Replacement Cylinder Heads
Diagnosis:
3.6L cylinders have been improved for durability by upgrading the valve seat and valve guide material. In order to verify that the latest upgrade is incorporated in to the cylinder head received from service parts verify the part number and Julian build date of the cylinder head
Part Number- RL141353AC or higher - left side head
Part Number -RL141352AD or higher– right side head
And a Julian build date of 2062 (206th of 2012) or higher .The build date is stamped on the outboard side of head at the center just below the rocker cover sealing rail

The quote above is from a Wrangler forum; Penstar recall to replace cylindar head - Page 6 - JeepForum.com

Found a picture of the head also, not sure if that's already the 'new design';
 
#23 · (Edited)
I would think its a part of the head with the exhaust manifold, it was pointed and discussed in the other forum that the ultra short exhaust vs. the longer might cause issues. Interesting discussion but all speculations.

Only hard statement is the posted one above, but again it's a Wrangler Forum not sure if they have the same head?

The story made its way into the news in the past, but it is still kind a quiet; That's an old one but never heard any since? Chrysler to fix defect in 1,000 V-6 engines

There are the same assessments in the referenced forum you made, the issue is probably related to higher outdoor temps. Maybe more is coming up in summer again?
 
#24 · (Edited)
Oh it is to laugh. That article is from August, the last time we heard anything from CJF and further down it says " The problem has been discovered in about 7,500 Chrysler V-6s, and there could be more,"

Further I suspect that heat and vehicle load are probably contributors so heavier (both Wrangler and GC are over 4,000 lbs) vehicle probably are more likely to experience the problem.

Personally would not be surprised if we started seeing "diminished value" for '11 and '12 V6s in NADA and KBB and then there would be an uproar.

BTW think that is a driver's side head that has been sliced in half, and the combustion chamber is on the bottom of the one on the right. What I do not see is where are the intake valves. There does appear to be what may be a coolant water inlet/exit at the flywheel end and going though the center but I do not see an inlet/exit opening by the cam chains (#2). This is part of what has bothered me from day one, normally the front cyl (chain end) runs cooler tan the rear and the center (#4) is hottest. Oh well will know someday.

ps just looked at some assembly line photos and it looks like there is a water inlet high at the rear of the head and what may be an outlet in the block just behind where the chains would be. Dunno which is inlet and which is exit but suspect an engineer would tend to put the cooler water in at the hotter end which normally would be near #6.
 
#27 ·
I agree even if the number has now reached 10,000 that is still only .7% of all Pentastar equipped vehicles. But what if heavier/larger vehicles or vehicles operated in high load conditions (off road, towing) are more likely to experience the failure. That would raise the failure expectancy of V-6 GCs made before June 2013 considerably. 10x ? 100x ? Who knows ? Chrysler does and they aren't talking.

One thing I do consider probable is that the failure rate of Wranglers seems to be even higher than GCs. Major difference: 3.70 rear gear.

Personally have always believed in running engines on th cool side of the specs since I live in a hot climate. Now even more so.
 
#28 ·
Maybe it seems to affect Wranglers more because the owners yell louder. Probably nearly every Wrangler owner is on a forum. WK2, maybe 5% or less of owners are active on a forum. You probably won't hardly find any failures among Journeys (if searching the interwebs)...
 
#29 ·
Add my 2011 GC to the list, with an assembly (build) date in Feb of 2011, if I remember right.

CEL light went on just after xmas. I dropped by the dealer expecting to hear that all the snow trailblazing I did in Canada over the holidays loosened a sensor or something, and jaw dropped when he said the code was a misfire, and would probably mean a new head. To verify, he said they would clear the code, and if/when the CEL went on again, to come back for the 2-day operation. A week later it did, and has been fine since with a new head.

What surprised me the most was how nonchalant he has about it, and that he had one already in stock. Their shop had already done over 15 of them, apparently (northern NJ), and they understood the root cause to be a machining (not design issue) on certain 2011/2012 engines. Something to the effect that the poor tolerances in the head itself allow for valve seating issues, ergo misfires.

It's a warranty issue covered under the 5/100 powertrain warranty of the JGC. My truck had 28K (mostly highway) when it happened.

I love my JGC, but I'm skeptical that it's a long-term keeper. Pentastar issues, transmission performance (low-speed intermittent clunking), head unit gremlins (disappearing HDD content)... all point to a beta release. May trade before the 3/36 runs out, tho it will be a difficult break-up.
 
#30 ·
i think i may have this. Need to take it to the dealer still. Driving last night and i suddenly felt a vibration like a gear slipped or something and heard a slight thud. Next thing i know CEL comes on, and i feel a loss of power. Luckily power kicked back in before a steep uphill and i made it the rest of the 1.5 miles to home.

I'm at 35,800 miles... good to know if my problem is with a cylinder head i'm still good till 100K. whew....
 
#34 ·
^ NP. Sorry I misunderstood. I understand what you mean now -- a problem with ever application of the Pentastar.

We're still under 20k mi on ours. It's still been problem-free (keeping fingers crossed).
 
#35 · (Edited)
"Statistics don't lie but..." That is .5% of all Pentastars. However the issue seems to mainly affect heavier vehicles - over 4,000 lbs. So lets say that Pentastar equipped only make up (10%- Hemis - SRTs) 6% of all Pentastars. Even 10% of GC's failing would not impact that .5% of all statistic.

So far two things are evident: when misfires are reported (and not something normal like a bad plug) CJF just replaces the head. No problemo.

It appears to be a valve guide issue but load/gas has also been mentioned both of which can lead to detonation if there is a hot spot in the chamber and the hammering can wear a valve guide. Lotsa of other things could contribute (like a lean condition is #2 and/or #4 - most common reports).

All that said CJF has not produces any specific figures by car line which I suspect is deliberate.

Personally, I suspect that simply using a 5% cooler fast-opening thermostat and bringing the cooling fans in sooner to keep coolant in the 190F-200F range fully warmed up could have a significant impact on the issue.

Until then, if in stop-and-go traffic and the temp starts to climb, just turn the a/c on - it will turn the radiator fan on immediately.

Will be interesting to see as warm weater returns if the failures do also. Meanwhile I just check for misfires about once a month.
 
#36 · (Edited)
Interesting thread. I have a GC with 8900+ miles on it. I have had two oil changes at the dealers, and both times they put the wrong oil in. In lieu of 5W-20 they have put in 5W-30, and it is some really cheap bulk crap from Chrysler. The first time I took it back and made them change it to the correct weight, with Mobil 1. This time, we have been snowed in, so I changed it, the day after, in my garage. I had 8 quarts of Mobil 1 in my cabinet. I am wondering if using the incorrect weight of oil in this engine would contribute to these failures, especially in extreme cold weather conditions. I do not put E-85 in it and only use premium gas, since is Ethanol free and 100% gasoline. Just curious if we are looking at this problem in the future, and glad all this information was here.
 
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