|Topic Review (Newest First)|
|10-04-2015 02:17 PM|
|10-04-2015 02:13 PM|
|10-04-2015 10:41 AM|
Although, as news is developing, it seems FCA might also be guilty of 'significantly' under reporting deaths & injuries. It'll be interesting to see if any are related to failed timing chains.
|10-04-2015 10:23 AM|
|15hrs to Frisco||
I may be a big critic of my home state of CA on almost anything they do but at least they did get a very good "Lemon Law" through that is pretty good as far as the consumer goes. It's hard for me to believe with all the thousands of miles of testing (maybe millions) these companies do before making a vehicle available for sale that there could be problems like this.
|10-04-2015 08:33 AM|
|10-04-2015 06:57 AM|
|usmc1811||I had a GMC truck ( brand new ) with the 5.3L V8, that had the 4 cylinder shut down capability. The engine was bust from the start. I changed the oil ( at the dealership ) every 3000 miles and in between oil changes it consumed a quart of oil or more every time. The low oil warning would come on, I would immediately take the truck to the dealership. The mechanics could never figure out why it would lose a quart or more of oil in such a short time. They were in contact with GM through out the problem. We are talking months of back and forth with the dealership. After many complaints from me, GM wanted the dealership to take the truck and road test it for several months to help figure out where the oil was going. The dealership was stuck in the middle on this effort. GM would only pay for a little subcompact car while they figured out what was wrong with the engine. I needed my truck not a subcompact car. I would not go along to get along with GM. I ended up getting rid of the truck at a loss, the truck had less than 20k. I have not bought another GM product since.....AND I never will.|
|10-02-2015 09:04 PM|
|15hrs to Frisco||I've skimmed through this thread and learned a lot here but I don't recall this being asked before: how is the way GM shuts down cylinders on their V8 push-rod engines different than how the MDS in the HEMI V8 works? I don't currently own a GM product with a V8 so I'm not hanging out reading boards about them much but I don't think I've heard about any problems like this with their system.|
|10-02-2015 08:39 PM|
Timing chain failure on the Dodge Challenger
No, MDS is controlled by special lifters and solenoids. It has nothing to do with the cam or VVT.
MDS existed before VVT was introduced in the Gen-III HEMI.
|10-02-2015 08:33 PM|
My theory on that has been that it isn't the mds, per se, that is the issue. It is the programming that defines the threshold for mds...that failures where imminent because the mds was allowed to operate at too high a threshold (and possibly at too low an rpm). It's like a 4-banger working too hard and lugging at too low an rpm...yielding excessive vibration and torque fluctuation, which acted like a buzz saw on the already-marginal timing chain guides. Change the programming such that the mds taps out earlier at the onset of significant engine load, I suspect the problem disappears. Mds can work troublefree, but it should be reserved for light engine load (and maybe not too low an rpm). That's when it can deliver maximum mpg, anyway.
Think about it...most cars with an i4 engine are typically not geared to run overdrive at 1500-1600 rpm. Usually it is 2200 rpm and above. Once you get below that point, the i4 is working pretty hard and lugging as far as power pulses (significant vibration and torque fluctuation). Well, that is essentially what is happening in an mds v8, when you run hard at 1500-1600 rpm (as in hwy speed operation on a slight grade or slight acceleration). It's not that the engine can't do it, as far as output. It's just that the vibration of lugging is not particularly good on certain "critical" parts in the engine. An mds v8 running at 1500-1600 rpm is comparable to a full-v8 running at 750-ish rpm...and who would think that is a particularly wise thing to do on a v8? That's my theory, at least.
|10-02-2015 08:17 PM|
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