But there are only some 30,000 5.7L Hemi Challengers with MDS out there. Not the same thing, not the same thing at all. You can't include every Hemi or every 5.7L ever made. Remember the 5.7L got a redesign in 2009, so the pre-2009 doesn't really have any bearing on the instant problem.
First gen HEMI with MDS ran from 2005 to 2008, so for 4 years. Granted those have higher mileage on them now and they probably made more of them due to HEMI novelty factor back then and lower gas prices. But I for one don't believe that all those 28 TCs for that week were all just for Challengers. And that number compares to 34 for first gens. Sure, one shouldn't read too much into it. But I still think it is a data point.
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All Mopar all the time: 2010 Stone White Challenger R/T, 2006 Inferno Red Magnum SRT8 & a 2009 Journey SE
It seems that in the case of the failure that the chain and guide shoe break. Do they break at the same time or does one break before the other? It is doubtful that they break at the same time but one's failure is surely related to the other's failure. Given that, would it seem likely that the broken chain breaks the guide shoe? Or the broken quide show breaks the chain? I cannot see how a broken chain can break the shoe. If the chain were to break, it would all of a sudden lose tension and ball up in the timing chain area. But if the guide shoe were to break, I can see that forcing the chain to break in that all tension would be lost and the chain would try to ride on top of the sprockets. At that point if the chain could not fit around the outside of the sprockets unmeshed, then something would have to give. Either the chain or the sprockets. This is the more likely scenario and would prove that the chain is not failing due to it being a single roller.
If my above hypothesis were to be correct, then we would have to figure out why the guide shoe breaks. Does it wear out? Is it holding tension? Is the chain slapping it causing it to break?
The whole reason for this rant is to rule out chain strength. I firmly believe that no matter how strong the chain is, it would be breaking in these motors anyway due to another failure. I thing we should be focusing on that instead of talking about another engine having a duplex or triplex chain and that is somehow superior. While those chains may be stronger, I firmly believe the current chain is far stronger than it has to be to do the job.
Mainly from Desert Bum's analysis I also concluded that the tensioner assembly breaks and that the chain follows. There's been motors opened where the shoe was in bad shape while the chain was still OK. So a stronger chain wouldn't hurt, but it doesn't seem to be the source of problem. Unless I missed anything, the speculation revolves around whether the MDS operation generates vibrations that resonate with the tensioner, or a jerking of the chain (on/off MDS) that stresses it. In and of themselves vibrations aren't always destructive, but when you put together those that come with the MDS operation and the chain failures that only occur on certain MDS-equipped engines...
And I'm no mechanic but I doubt that the oil screen is a factor - I think it's just a minor and colateral victim of the excessive vibrations, either from the MDS or from the chain slapping around as the tensioner/guideshoe is disintegrating (probably the former as I think that at least one was found dislodged inside a healthy motor).
Those annoyed at how active and long-running this thread is can always unsubscribe, eh? I personally think it's important to keep it alive. One, someone could eventually have an epiphany, and two,... it is harder to ignore for Chrysler. I would love for an official to chime in and state that we're full of it and what is really going, or not going, on (I'm a dreamer) - too bad they have people on other boards, but not this one.
Last edited by USRWDV8; 12-23-2012 at 06:06 PM.
Reason: Just anal
First gen HEMI with MDS ran from 2005 to 2008, so for 4 years. Granted those have higher mileage on them now and they probably made more of them due to HEMI novelty factor back then and lower gas prices.
In 2009 Chrysler redesigned the 5.7L, Part of that redesign was to change the timing chain (now thinner) and the timing chain tensioner (now a spring loaded plunger type).
The pre-2009 5.7L had a leaf spring design for the timing chain tensioner. We have a spring loaded plunger type tensioner. You cannot include 2005-2008 models of the 5.7L because they are completely different engines of a completely different design.
Many before you have tried to make a similar argument of hundreds of thousands, someone even mentioned millions, of 5.7L running around out there so just having 30 timing chain failures is nothing. Bring that back to reality and knowing there are only about 30,000 R/T with MDS and those 30 failures represent 1 in 1,000 cars affected, and that's just using data from this forum alone. Factor in what isn't being reported here and you are likely at 1 in 250 cars affected.
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why is it limited to 30,000 R/Ts?????? the SAME engine with MDS VVT is used in the 300 Charger RAM Jeep with no mechanial failures on vehicles with much higher mileage. it has to be tune related, slamming the MDS on and off or possibly advancing retarding timing excessively, something unique to the Challenger.
If the guide shoe was wearing out it would happen on all models across the board or an inadequate chain would also be failing at a higher rate on high mileage vehicles.
also 1 in 250 is really exagerated, if it was anywhere near that upon searching the internet there would be reports on consumer sites etc. about the only ones are on this site. people complain about everything on the internet from washing machines to you name it. you really htink thier 30000 dollar car failing would not get posted?
So, does this affect the 12 or 13 R/T automatics in any way? Im sure this has been discussed somewhere in this thread but I am not going to read 200+ pages of anyone's thread!! hell no!!
I would appreciate some infod. I just sold my 2010 SE in hopes of getting a 12/13 R/T automatic. Thanks.
So, does this affect the 12 or 13 R/T automatics in any way? Im sure this has been discussed somewhere in this thread but I am not going to read 200+ pages of anyone's thread!! hell no!!
I would appreciate some infod. I just sold my 2010 SE in hopes of getting a 12/13 R/T automatic. Thanks.
That will not be known until a bunch of '12 & '13s get 30k miles on them. Or until Chrysler speaks up and tells us what if anything was done to resolve the problem. OK, so we'll have to wait for the '12 &'13s to get 30k miles on them.
In 2009 Chrysler redesigned the 5.7L, Part of that redesign was to change the timing chain (now thinner) and the timing chain tensioner (now a spring loaded plunger type).
I didn't know about the different tensioner design.
And I know that you cannot compare these TC failures with the first gen since in the second gen it primarily effects Challengers. I was still interested in some general numbers. For example, I would find it interesting what for example the weekly TC demand is for the new Mustang 5.0. Just to have something to compare it to. Of course, all that doesn't do you any good when it happens to you...
That will not be known until a bunch of '12 & '13s get 30k miles on them. Or until Chrysler speaks up and tells us what if anything was done to resolve the problem. OK, so we'll have to wait for the '12 &'13s to get 30k miles on them.
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