I'm out of my depth here, but my gut feeling was that it was the tensioner that would first go and then make the chain break. The vibration I feel during MDS activation/deactivation, and sometimes steady operation (not always) is what made me think of resonance, but that's just a theory. I never had 25 people working under me in total awe...
To elaborate on your point, I agree that the tensioner shoe failing first and then mucking up the chain seems very plausible to me, as well. The matter of resonance would still need a good number of cycles to actually fatigue a part. Hence, I am not convinced that just mds activation/deactivation could do that. It's too short an event to get much duty cycle, IMO. The steady operation scenario is what would strike me as more likely to capitalize on accelerated wear...specifically if mds spends a lot of time at moderate to high load (as in climbing a long grade), where you really can notice vibration/noise from its operation.
It's more than just running mds on flat ground (even though a good number of incident reports seem to cite the failure happening at this moment). I think the accelerated wear or fatigue is coming about during routine, long slogs on uphill grades...where the load is enough that the mds is working pretty hard, but not necessarily getting to that threshold where it will hand it over to full v8 mode. It is moderate engine load and possibly exacerbated by incidental operation at 1800-ish rpm, where vibration may be most intense on the chain system. Moderate engine load at 2000 rpm (for example) could just as well do it, too, but I'm just trying to note a worst-case zone. As you get further away from the WCS, accelerated wear/fatigue is still happening, but it takes increasingly longer to produce the failure.
It's not that I really needed 370 hp...but having 150+ hp riding shotgun at a moment's bidding w/o a 6000 rpm moonshot is what makes me feel like I'm in the right car for me. The roar of a v8 seals the deal!
The Google keyword is "ethanol-free gas". The truth is coming to light. Check out http://pure-gas.org/
Last edited by randycat99; 08-06-2012 at 01:38 PM.
LAST post by your favorite a$$hole, just to give the youngsters a quick, easy demo, that ANY of you that have an OHV, pullcord start lawnmower, of how MDS works, hokay?
Fire it up to be sure it runs. Now, remove the valve cover, if you dare, now, remove BOTH rocker arms, again, this is very advanced, YOU may never get it running again without calling a professional. Now pull the cord with no rocker arms...what IF the intake rocker arm was operational just long enough for the first gulp of 14-1 air fuel mixture, fired it as usual, THEN the rockers were off.....that air/fuel charge exploded one time, peak cylinder pressures rose ENORMOUSLY and then, they NEVER left the cylinder, which now has no rocker arms and YOU are TRYING to yank that cord to pull it through the next rotation with what started as maybe 175PSI & went maybe 10.5x that when the plug ignited it that one time before the rockers came off...think...no, go try the experiment, if you have a wrench or two & go ahead & show EVERYBODY what an idiot this guy is...but don't talk to me about it, I don't know sh!t....
You are a dandy, mr. Expert.
Just an fyi, I have done 14 complete mopar restorations, from a 57 Fury to a 68 Hemi Road Runner. I have built over 50 mopar motors, but I still DON"T KNOW IT ALL. I don't even care for Holiday Inn Express.
That being said, I fired up the predator Saturday and turned MDS off until there is some resolution to this deal.
__________________
09 R/T 28J, built 8-7-08, K&N CAI, catch can, SRT scoops, struts, springs, 70 R/T stripes, SRT wheels and tires.
Thought about this "Harmonics" theory over the weekend. I'm not saying that this isn't the case, just throwing this out there.
If it was harmonics the entire chain would have stress cracks showing up in it, would it not? Short of having it magnafluxed there is no way to tell.
Could the harmonics be working on the tensioner, then the tensioner causing the chain to fail? From reading destertbum's details, I am pretty sure he proved the tensioner was the initial problem, then one link of the chain.
But I am getting old and it has been a few days since I read this thread.
The timing chain on my 2010 R/T just broke, with only 27,000 miles, and yes it lead to all kinds of other failures too! Just got off the phone with the dealer and not sure what's going to happen for sure now??? I told him I just wanted a brand new crate motor, but he had to talk to file a form with Dodge to find out. He also said that's what he was requesting. 8/6/2012 Seems like I read on here a year or so ago about somebody that had an engine failure and they were able to get a bigger engine by paying the diffrence?? Anybody remember that?? And for anybody that thinks the VVT MDS 5.7 is as bullit proff as the Ram motor, I have a 2005 Ram with 192,000 on it and have never had a problem!! The R/T engine ain't even close to being the same!!
My dealer hadn't seen it either, until they finally got mine apart today!!
The issue I have here is about attitude, not the numbers.[/QUOTE]
Again, all I'm saying is that the attitude of "I haven't seen it so it must not be a problem." doesn't help anyone and it certainly doesn't help the people reporting their problems feel like those that are in a position to help care about them or the problem.
My dealer hadn't seen one either, until they got my car apart today!! so you're right, it definately happens!!
The issue I have here is about attitude, not the numbers.
Again, all I'm saying is that the attitude of "I haven't seen it so it must not be a problem." doesn't help anyone and it certainly doesn't help the people reporting their problems feel like those that are in a position to help care about them or the problem.
My dealer hadn't seen one either, until they got my car apart today!! so you're right, it definately happens!!
Sorry to hear about your problem and hope it works out well for you in the end. Were you in MDS mode when it happened?
aghelipilot, sorry to hear about your incidence. I don't think people who asked their dealers on whether they had seen this were trying to play down this issue. Rather to get a feel on whether this happens on other HEMI VVTs as well. As we know now, there were a few incidences reported online. But nothing like what has been reported here on challengertalk...
__________________
All Mopar all the time: 2010 Stone White Challenger R/T, 2006 Inferno Red Magnum SRT8 & a 2009 Journey SE
Yes, please give us the breakdown, aghelipilot...road conditions, rpm, speed, mds state, anything you can remember. Were you pretty agnostic toward mds on or off, or did you tend to find ways to keep it off during that 27k? 27k mi is pretty young, too! Is that the lowest mileage reported on this failure, I wonder?
The issue I have here is about attitude, not the numbers.
Again, all I'm saying is that the attitude of "I haven't seen it so it must not be a problem." doesn't help anyone and it certainly doesn't help the people reporting their problems feel like those that are in a position to help care about them or the problem.
My dealer hadn't seen one either, until they got my car apart today!! so you're right, it definately happens!![/QUOTE]
Good luck Pilot,
I know in past comments I bag on the techs pretty hard, rightly so in most cases. However you may find one of a handful of guys that actually care. If the will let you, try to get some pictures of any and all broken parts and pieces and a good description of the work performed. I am curious if the broken parts are looking the same as some of the pics posted regarding the timing chain failure issue.
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.
Linear Mode
