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Old 08-25-2014, 03:11 PM
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2012 jk head going to be a problem? AA, AB, AC?

I know this has been on here before can someone send me the link or let me know what to look for.

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Old 08-25-2014, 03:23 PM   #2
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You probably won't have the problem. Most don't (including mine, with a build date in the middle of the "bad zone"). The AA/AB/AC refers to the end of the part number of the head. AA is the first design, AB was a (supposedly improved) redesigned head, and AC is the latest design that supposedly fixes the problem for good.

There's nothing to look for, it's an internal problem. Your first indication will be a louder-than-usual ticking from the engine (and the 3.6 is pretty noisy in the valvetrain anyway), or a check engine light with the associated codes.

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Old 08-25-2014, 04:51 PM   #3
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Old 08-28-2014, 07:58 PM
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thanks for the help
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Old 08-28-2014, 10:39 PM   #5
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You probably won't have the problem. Most don't (including mine, with a build date in the middle of the "bad zone"). The AA/AB/AC refers to the end of the part number of the head. AA is the first design, AB was a (supposedly improved) redesigned head, and AC is the latest design that supposedly fixes the problem for good.

There's nothing to look for, it's an internal problem. Your first indication will be a louder-than-usual ticking from the engine (and the 3.6 is pretty noisy in the valvetrain anyway), or a check engine light with the associated codes.
What are you talking about? Build date in the middle of the bad zone? If you don't have AC heads more than likely you'll have problems sooner or later. The "bad zone" heads are finding their way back into the "good zone" build dates - 2014s and 2015s to be exact.

Good luck with your bad zone heads.

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Old 08-29-2014, 12:48 PM   #6
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I don't recall the exact months listed, but there was a period of time that was supposed to be worst. I've got a Feb 2012 build date, which was during that time and yes, I have the AA design.

And what are YOU talking about with this "more than likely?" Because the last I saw, Chrysler is saying that less than 2% of all Pentastars potentially affected have actually been reported for problems. Maybe that's changed, but until it gets above 1/3 or so, there's no reason for ridiculous hyperbole.
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Old 08-29-2014, 01:33 PM   #7
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I don't recall the exact months listed, but there was a period of time that was supposed to be worst. I've got a Feb 2012 build date, which was during that time and yes, I have the AA design.

And what are YOU talking about with this "more than likely?" Because the last I saw, Chrysler is saying that less than 2% of all Pentastars potentially affected have actually been reported for problems. Maybe that's changed, but until it gets above 1/3 or so, there's no reason for ridiculous hyperbole.
The failure rate isn't below 2%. It's significantly higher. That's why they extended the warranty on the left head to 150k/10 years for the 2012. There is no bad zone. It's the entire 2012 model year and about a month into the 2013 MY. The last ones built in July/August 2012 received the AB head, which still weren't quite right and have seen the same failures.

As mentioned in the post above, there is some evidence that the busted heads taken off the 2012s are being remanufactured and put in new 2013/14/15 models. So, IMHO, it may actually be better to have a 2012 than a newer model because we have the snazzy extended warranty. lol, what a turn of events.
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Old 08-29-2014, 07:15 PM   #8
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Cutoff date is 7/27/2012. Before that date, head will fail. An engineering design fault centered around the single exhaust output port which had not been reinforced with enough material to sustain the heat. AB heads were very short lived, and superceeded with AC heads which corrected a camshaft area issue. Some 2012 heads fail at 10K miles, others at 50,000 miles, but all will eventually fail. I traded both my 2012's to avoid the issue.
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Old 08-29-2014, 07:38 PM   #9
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The 3.6 was used in other model jeeps, prior to 2012, through current. So if they are all going to fail, which I question, then I sure hope that Chrysler/Jeep has several warehouses full of replacement heads, because this could go on for years.......
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Old 08-29-2014, 09:04 PM   #10
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Xena1, bought a new 2012 JKU, build date was June 2012, picked up in July 2012.....I got 15,000 miles so far...Are you saying/betting my Jeep will fail eventually? I find this hard to believe a statement can be made that ALL 2012's will fail...Want to elaborate please ....
Your statement:......Some 2012 heads fail at 10K miles, others at 50,000 miles, but all will eventually fail. I traded both my 2012's to avoid the issue.

Hopefully I have a good vehicle, $30,000 was the price, and can't believe EVERY 2012 Wrangler is failing, sorry Dude......Don't believe this would be a true statement for us Jeepers...Just my opinion.. They made a lot of Wranglers in 2012......
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Old 08-30-2014, 07:50 AM   #11
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All I am saying is engineering design failures don't discriminate. Not like a bad batch of parts from a production run or vendor. Chrysler would not have extended warranties on these build dates without expecting a 100% failure rate. No recall was made, because it is not a safety issue. So if your julian date in 2012 is less than 207 then expect a failure.
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Old 08-30-2014, 09:04 AM   #12
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I think you're being a bit misleading on your point Xena1. While I do agree all heads built before the design change have the potential to fail, to say they all will is not correct. I live in a colder climate. In our area, (since we have an automotive machine shop) we have seen exactly one 3.6 head in the last three years.(from a caravan) My buddy is the parts manager at the local Chrysler dealership, they haven't done any. I really believe the cylinder head design was flawed, because it runs too close in temp to its maximum design limitations. It doesn't take much to put it over the top. A hot climate is probably the biggest factor, but others like towing etc would do it too. Really anything that gets the head up that few degrees will cause problems. There will be many owners that will never exceed the head's (flawed) designed temp limitations, and won't have any problems. If they do, the extended warranty will look after it anyway.
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Old 09-01-2014, 07:19 PM   #13
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I think you're being a bit misleading on your point Xena1. While I do agree all heads built before the design change have the potential to fail, to say they all will is not correct. I live in a colder climate. In our area, (since we have an automotive machine shop) we have seen exactly one 3.6 head in the last three years.(from a caravan) My buddy is the parts manager at the local Chrysler dealership, they haven't done any. I really believe the cylinder head design was flawed, because it runs too close in temp to its maximum design limitations. It doesn't take much to put it over the top. A hot climate is probably the biggest factor, but others like towing etc would do it too. Really anything that gets the head up that few degrees will cause problems. There will be many owners that will never exceed the head's (flawed) designed temp limitations, and won't have any problems. If they do, the extended warranty will look after it anyway.
Hope you are right. But as an airplane pilot, I would never fly a plane with an engineering defect. I remember your build date is 204 so you should have the AB head. I really liked my 2012 Crush JK but trade it in for a 2014 Anvil JK.
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Old 09-01-2014, 07:57 PM   #14
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Hope you are right. But as an airplane pilot, I would never fly a plane with an engineering defect. I remember your build date is 204 so you should have the AB head. I really liked my 2012 Crush JK but trade it in for a 2014 Anvil JK.
Ha ha, can't blame you for that. It's not like you can pull the plane over if your engine starts to tick. I'd really like to find out what the real fix was for the head. Probably something will come out eventually. The tidbit about Chrysler using hardened valves, guides and seats is bs. They have been using those hardened items since back when they removed the lead from gasoline.
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Old 09-01-2014, 08:18 PM   #15
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Ha ha, can't blame you for that. It's not like you can pull the plane over if your engine starts to tick. I'd really like to find out what the real fix was for the head. Probably something will come out eventually. The tidbit about Chrysler using hardened valves, guides and seats is bs. They have been using those hardened items since back when they removed the lead from gasoline.
I read somewhere on one of the web car mags the left head was cracking...

Which makes more sense... if they just replaced the left head with new guides, valves and seats - then the right head would eventually fail.. which they haven't.

I think this is specific to the left head design and the much higher temps it sees than the right head.

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