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Unread 02-16-2012, 02:14 PM   #91
jwmbishop
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Quote:
Originally Posted by tolnep View Post
one source (dealer) said it was because of bad valves that were sticking, causing carbon buildup, pre-ignition and other problems. though there seems to be a prevalence for cylinder 2 so i dont see how bad valves would only manifest themselves in one cylinder of the motor.
Conceivable. One merely has to look at the first generation of the GM L27 3800 HO. Interchangeable heads (that is same assembly can go on either side) yet consistently #2 would drop an exhaust guide first time the engine hit 215 degrees op temp. Due largely to that water jacket from block to head flowing faster than the other jacket transfers. Field repairs for a blown head gasket etc. often erroneously swapped the heads and the problem would occur again without a subsequent overheat (as the head was already dinged by the first overheat). We fixed a bunch of em by using over sized bronze guides with a bunch more interference in the press fit.

Similar issue with the 6G73 (2.5L) v6 mitsu - right side would burn up the cam bore for "no apparent reason" (later determined to be thermal expansion and continued operation longer than 6 hours at normal temps causing the center bearing support to rise and run as much as .0027 out of line thus cutting off flow through to the front half of the cam journals). Our first few repairs (weld any damaged bores and overbore for shell type bearings) were so successful we picked up the contract to take brand new off the shelf replacements, strip em down, cut the cam bore for shell inserts (MUCH more forgiving of line issues and the ability to pass the oil BEHIND the shell rather than through the bearing for continued flow) and assemble (rather than the original config of cam finish bore cut directly into the castings). Did some 250 of em to stock west coast dealer shelves until the redesigned ones could make it to market.

But as to the Pentastar (being that we are not in the first generation of design) - I tend to believe there is no "big issue" looming - rather some units based on their specific use and duty cycles may exploit an engineered minimum such as casting thickness etc... and manifest as one valve being more problematic than the others. I also Agree with the VVT assesment - my Northstar is VVT and has ticked like a mad man at some times and run quiet as a ghost others (and I drive it pretty hard impressed as I am at the way it just keeps making torque all the way from 2800 to 6300 RPM). 275K on the clock now! I think VVT coupled with the extremely fast ramp speeds on a roller cam can make a bit more noise than we are accustomed to.

And as with any process there could be a few slip past with a misaligned bore etc (although with computer inspections it would be a surprise that many if any do).

Time will tell...

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Unread 02-16-2012, 04:25 PM   #92
offcamber
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This morning I went back to the dealership that said mine was fine (sounded just like stock unit is what the sheet said). I asked them what they did to diagnose the noise. They said they compared it to another 2012 on the lot. I got a little pissed and explained what has been reported here. They said if it sounds normal, what can they do. They offered to let me listen myself so we grabbed a bunch of keys and went outside. We started 7 2012s and everyone sounded like mine with the tick sound. I've yet to see anyone post a video/sound clip of a 2012 that sounded different than mine, so I'm guessing the tick is the way the engine normally sounds. If someone has one that doesn't make the noise, record a video/audio of it and post up. Otherwise I think I have to assume it's normal and there is just an internet freakout going on over nothing...
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Unread 02-16-2012, 08:08 PM   #93
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Quote:
Originally Posted by offcamber View Post
This morning I went back to the dealership that said mine was fine (sounded just like stock unit is what the sheet said). I asked them what they did to diagnose the noise. They said they compared it to another 2012 on the lot. I got a little pissed and explained what has been reported here. They said if it sounds normal, what can they do. They offered to let me listen myself so we grabbed a bunch of keys and went outside. We started 7 2012s and everyone sounded like mine with the tick sound. I've yet to see anyone post a video/sound clip of a 2012 that sounded different than mine, so I'm guessing the tick is the way the engine normally sounds. If someone has one that doesn't make the noise, record a video/audio of it and post up. Otherwise I think I have to assume it's normal and there is just an internet freakout going on over nothing...
Just to point out the obvious, having them all sound the same (bad) doesn't make them all good.
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Unread 02-16-2012, 10:08 PM   #94
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I figure when the mis fire code pops up the valve is gone is the waiting game? They all sound the same THAT IS FUNNY. Ask why is the left bank louder than right?, louder gerbils? well if these v6's turn out to be yet another STORY, i see an LS in future.
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Unread 02-17-2012, 03:17 AM   #95
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No, BUT, that seems pretty unlikely that all of them would be bad. Like I said, I've yet to hear one that didn't sound exactly the same. I posted her and on another forum asking for anyone that has a Jeep that doesn't have the ticking to post up a recording of it, but so far that hasn't happened yet.

I strongly suspect this is just another case of a bunch of folks on the internet seeing a problem where there isn't one.(me included). I found myself arguing with the service advisor because they weren't fixing my Jeep while he looked perplexed at what to do. I realized that he was trying to help but wasn't sure what to do since he didn't have any real evidence to act on to start replacing things on my engine. Look at how many posts there are where dealers replaced parts and nothing changed. 7 Other brand new Jeeps sound just like mine so I don't really think I can expect them to do anything. I can't find a single Jeep that doesnt have the sound, all we have to go on is a few folks who say theres doesn't have it, but since no one can produce an audio clip of theirs that doesn't have it, I have to conclude that they may very well have one that sounds the same as mine, they just don't realize it...


Quote:
Originally Posted by AZBob View Post
Just to point out the obvious, having them all sound the same (bad) doesn't make them all good.
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Unread 02-17-2012, 04:41 AM   #96
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I am still considering to buy a 2012 RUBI I am waiting for a response to offcamber remarks I feel he has a legit statement according to him the dealer let him start 7 new pentastar engines up and they all ticked My wife has a 3.6 pentastar 2011 GC and it is silent I mean very silent !!! I would like to know if there is a diffence between a 2011 3.6 in a GC ( Grand Cherokee ) and a 2012 3.6 Wrangler and If so what is the difference ? I was at a dealer lot the other day and a couple started a New GC up for a test ride and that engine had a knock so loud that two other people standing nearby actually shook there heads at the sound it was making Did Chrysler do something different with the 2012's ?
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Unread 02-17-2012, 05:00 AM   #97
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I've listened to the video some have posted with the extreme (loud) ticking which sounds like the valve train is falling apart.
Sounds nothing like mine. Mine is nice and quiet, don't even notice any valve train noise on mine.
BUT, I only have 800miles yet on it.
These don't all sound the same as has been shown by those whom have recorded theirs with overly noisy lifters. Plus the thousands of 2012 owners not having this problem are not involved with discussing this issue.
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Unread 02-17-2012, 06:50 AM   #98
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Unread 02-17-2012, 08:23 AM   #99
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Mine seems fine but ... just once I was sure I heard something much louder than normal at startup. Really, what's the big deal? We've all got a long, long time on our powertrain warranties. I can't get over how snappy my Jeep is, I absolutely love it. If somewhere along the line I need a new cylinder head, so be it. Chances are that will be LONG before the warranty expires if people are having problems already.
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Unread 02-17-2012, 09:17 AM   #100
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Summary: If there is an issue with the valve lash adjusters (VALVE LASH ADJUSTERS, people -- NOT lifters) not pumping up that causes the engine to sound tappy, it's harmless to the engine. Back in the old VW Beetle days we had the saying "a tappy engine is a happy engine", of course that was with a vehicle that had solid lifters and rocker arms with screw adjusters rather than with a roller cam follower directly pushed on by a cam, but same principle applies -- it's too-tight valves that cause issues (i.e., burned valves), not too-loose valves (which cause a slight loss of power but the valves tend to live longer too).

If there is an issue with a valve that burns easily, you have a 5 year powertrain warranty, and I can guarantee you that it will burn within that 5 years, cause a code, and be warrantied.

I asked my (non-Chrysler) mechanic why there was that big foam and plastic atrocity on top of the engine and he replied, "it's for sound deadening, because this engine makes a surprising amount of intake and valve train noise and people would complain if that sound deadening wasn't there." All of the new aluminum engines sound noisy because they don't have the cast iron mass to absorb noise that the old iron engines had. My guess is that this also explains why the engine seems a bit noisier on one side than the other -- if you pop up the plastic monstrosity you'll notice that the tuned intake manifold runners join on the driver's side, and it is plastic, so it has *no* sound deadening properties and transmits valve train noise directly, this also means that the foam sound deadening material is thinner on that side.

My old 4.0L made plenty of clattering from its hydraulic lifters on cold start, and it had enough sound-deadening iron to use as a boat anchor. By comparison my Pentastar is quiet and smooth. I have 9,000 miles on it now, and notice the valve train is slightly more clattery since my last oil change at 8,000 miles, but I'm pretty sure that's the oil I used, a synthetic that's on the thin side of 10W30. I'll switch back to the previous oil I used at 12,000 miles, and I expect that'll be that.

One last thing: My understanding is that the Sport models don't have the sound deadening blanket under the hood that my Rubi has. My guess is that this does make a real difference in how loud the engine sounds from the cockpit and from outside the vehicle. If there's other cars around it's hard to tell that my Rubi is idling even if you're leaning against it, I've had more than one person leaning against my Rubi as we're watching the next person in line tackle an obstacle and suddenly start as he realizes that my Rubi is running, it's just in Park with the handbrake set.
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Unread 02-17-2012, 09:32 AM   #101
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Quote:
Originally Posted by badtux View Post
Summary: If there is an issue with the valve lash adjusters (VALVE LASH ADJUSTERS, people -- NOT lifters) not pumping up that causes the engine to sound tappy, it's harmless to the engine. Back in the old VW Beetle days we had the saying "a tappy engine is a happy engine", of course that was with a vehicle that had solid lifters and rocker arms with screw adjusters rather than with a roller cam follower directly pushed on by a cam, but same principle applies -- it's too-tight valves that cause issues (i.e., burned valves), not too-loose valves (which cause a slight loss of power but the valves tend to live longer too).

If there is an issue with a valve that burns easily, you have a 5 year powertrain warranty, and I can guarantee you that it will burn within that 5 years, cause a code, and be warrantied.

I asked my (non-Chrysler) mechanic why there was that big foam and plastic atrocity on top of the engine and he replied, "it's for sound deadening, because this engine makes a surprising amount of intake and valve train noise and people would complain if that sound deadening wasn't there." All of the new aluminum engines sound noisy because they don't have the cast iron mass to absorb noise that the old iron engines had. My guess is that this also explains why the engine seems a bit noisier on one side than the other -- if you pop up the plastic monstrosity you'll notice that the tuned intake manifold runners join on the driver's side, and it is plastic, so it has *no* sound deadening properties and transmits valve train noise directly, this also means that the foam sound deadening material is thinner on that side.

My old 4.0L made plenty of clattering from its hydraulic lifters on cold start, and it had enough sound-deadening iron to use as a boat anchor. By comparison my Pentastar is quiet and smooth. I have 9,000 miles on it now, and notice the valve train is slightly more clattery since my last oil change at 8,000 miles, but I'm pretty sure that's the oil I used, a synthetic that's on the thin side of 10W30. I'll switch back to the previous oil I used at 12,000 miles, and I expect that'll be that.

One last thing: My understanding is that the Sport models don't have the sound deadening blanket under the hood that my Rubi has. My guess is that this does make a real difference in how loud the engine sounds from the cockpit and from outside the vehicle. If there's other cars around it's hard to tell that my Rubi is idling even if you're leaning against it, I've had more than one person leaning against my Rubi as we're watching the next person in line tackle an obstacle and suddenly start as he realizes that my Rubi is running, it's just in Park with the handbrake set.
FWIW, on my LS1, using Synthetic definitely increased the noise of my engine, so I switched back to conventional oil. Also, unless things have changed, Mobil 1 Synthetic used to be considered on the "thin" side. Some folks had good luck running Mobil 1 0W40.
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Unread 02-17-2012, 09:58 AM   #102
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Most "extended duty" synthetics are on the thin side, because "extended duty" synthetics usually use pour point depressants rather than viscosity improvers to get their viscosity rating (because pour point depressants last longer than viscosity improvers), and as these oils' pour point depressants wear out they thicken up. Thing is, it takes a *long* time for their pour point depressants to wear out. In one test of Amsoil, the oil didn't start thickening appreciably until 12,000 miles. So if you're changing your oil more often that, you'll always be running at the bottom of the viscosity spec with that oil.

The previous oil in my '12 Rubi was a synthetic, but it wasn't an "extended duty" synthetic. My valve train was noticeably quieter. So I'll switch back to that oil (the base Pennzoil synthetic) on my next oil change, since the current oil appears to be too thin to keep the hydraulic lash adjusters pumped up. So it goes.
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Unread 02-17-2012, 10:52 AM   #103
offcamber
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So post up a video of your "silent" engine, otherwise, I'm guessing it sounds just like mine...


Quote:
Originally Posted by AROSETO View Post
I've listened to the video some have posted with the extreme (loud) ticking which sounds like the valve train is falling apart.
Sounds nothing like mine. Mine is nice and quiet, don't even notice any valve train noise on mine.
BUT, I only have 800miles yet on it.
These don't all sound the same as has been shown by those whom have recorded theirs with overly noisy lifters. Plus the thousands of 2012 owners not having this problem are not involved with discussing this issue.
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Unread 02-17-2012, 11:02 AM   #104
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Originally Posted by JemLT1YJ View Post
Ya i would think you got a problem... Sounds like a desiel... Thank god for warranty.
I hear you there. Reading things like this make me happy I have a 7yr 160k warranty. Having a very mod friendly dealer, and knowing that they won't void my warranty also helps.
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Unread 02-17-2012, 12:02 PM   #105
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This may be a completely useless post but I am not a knowledgeable as many of you.

I have a '74 Chevy truck with the 350 that has a NOISY lifter (know we are not talking about lifters exactly but...) and I was about to tear the top end down. I mean, this thing sounded like hammer tapping the side of the engine. My dad showed up with a bottle of Lucas oil treatment with a gleem in his eye and said 'fire it up'.

It was hammering away as he poured the aditive in and in about 10 seconds, the noice vanished. I mean, vanished. Two years later and 6k miles and no noise as long as I add the additive with an oil change.
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