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Hey. I've read somewhere, a while back, that running with MDS On could cause damage to the engine in the long run. I've done a lot of research but can't find any reliable info on that. I turned off my MDS with my tuner about 2 years ago cause I'm running brylcream only resos, and wanted to cut the drone, and didn't want to cause damage to my engine...from what I've learned.
For the past few weeks, I spend more and more time on highways and I want to cut on the gas expenses... I can live with some drones, but is there any problems engine Wise? I'm not that quick on the pedal during winter times, it's cold out here (Québec) and tires are spinning every corner!
 

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No, you're fine. There was concern when they first came out with it, but it was all unfounded. There are people here on the forum with well over 100,000 miles on their cars, and going strong. Plus other car companies have similar systems (just by different names), and they don't have problems either.
Turn it on, save some fuel, and don't fret.
 

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Hey. I've read somewhere, a while back, that running with MDS On could cause damage to the engine in the long run. I've done a lot of research but can't find any reliable info on that. I turned off my MDS with my tuner about 2 years ago cause I'm running brylcream only resos, and wanted to cut the drone, and didn't want to cause damage to my engine...from what I've learned.
For the past few weeks, I spend more and more time on highways and I want to cut on the gas expenses... I can live with some drones, but is there any problems engine Wise? I'm not that quick on the pedal during winter times, it's cold out here (Québec) and tires are spinning every corner!
While I would agree with shots that there wouldn't be any "damage" using MDS, there would be more uneven wear as 4 cylinders always fire and have heat where the other cylinders are still moving without the heat until you get back to 8 cylinder mode again.

Bore wear is the number 1 problem with any engine and stem/guide issues are always number 2. Uneven wear on the bores and upper components are real with all engines and more so with MDS engines.

This is why we always suggest using ACES IV in the fuel as it reduces ring and bore wear by 6 times, stem and guide wear 4 times and 5 times less valve recession on soft heads. Since your heads are hardened and have hardened seats, the cushion and noise reduction using the ACES IV would be really good too.

Having extra topside down lubricity is always preferred to none.....like what typical gasoline has today! ;)

Regards,
Brian
BND Automotive LLC:driving:
440-821-9040
www.bndautomotive.com
 

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Hey. I've read somewhere, a while back, that running with MDS On could cause damage to the engine in the long run. I've done a lot of research but can't find any reliable info on that. I turned off my MDS with my tuner about 2 years ago cause I'm running brylcream only resos, and wanted to cut the drone, and didn't want to cause damage to my engine...from what I've learned.
For the past few weeks, I spend more and more time on highways and I want to cut on the gas expenses... I can live with some drones, but is there any problems engine Wise? I'm not that quick on the pedal during winter times, it's cold out here (Québec) and tires are spinning every corner!
No, you're fine. There was concern when they first came out with it, but it was all unfounded. There are people here on the forum with well over 100,000 miles on their cars, and going strong. Plus other car companies have similar systems (just by different names), and they don't have problems either.
Turn it on, save some fuel, and don't fret.
This is generally correct. The issue with MDS and dropped valve seats mostly was limited to the '06-'07 cars and even then, the numbers weren't huge. No more that about 60 cars have been reported across the various Forums with the issue. Given that the Forums have tens of thousands of members (over 70k members here alone) and that hundreds of thousand of vehicles were made in those years with MDS, the incidence rate is extremely low.

The hypothesis is that the uneven heat within the heads caused by long runs with the MDS on resulted in a sudden change after a short stop and restart (usually after refueling) that caused the seats to drop due to the thermal differential in the head between the aluminum mass and the valve seat.

By 2009, the head manufacturing process was changed for the valve seats and I've never seen any of that year or up have any issue with the valve seats dropping. Today both the 5.7L and the 6.4L use the MDS technology and there haven't been any reports of continued problems.

The short answer is that if you have an MDS engine built after 2009, the only reason to turn off the MDS is if you want to...not because you are risking the engine life.
 

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Discussion Starter #5 (Edited)
Man! That's what a call knowledgeable answers! Thanks a lot. I'm driving over 160 miles per day for work lately, and could really save a bit on gas! I appreciate all your answers.

Jay :bigthumb:
 

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Man! That's what a call knowledgeable answers! Thanks a lot. I'm driving over 160 moles per day for work lately, and could really save a bit on gas! I appreciate all your answers.

Jay :bigthumb:
Although the valve seats in the heads were one of the things I was talking about, I was also thinking about the stems, guides and rings with the lack of lubricity there. However, glad you found the discussions knowledgeable. :bigthumb:

Here is what I was thinking that solves those issues:

http://www.chargerforums.com/forums/showthread.php?t=252521

Regards,
Brian
BND Automotive LLC:driving:
440-821-9040
www.bndautomotive.com
 

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During extended highway time under MDS conditions, the system will reactivate the controlled cylinders to keep them from losing too much heat. The timing varies but it was usually every few minutes that the MDS would turn on the 4 dead cylinders for 5-10 seconds to warm them up and then turn them back off. At least that is what it did on my '06 R/T.
 

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During extended highway time under MDS conditions, the system will reactivate the controlled cylinders to keep them from losing too much heat. The timing varies but it was usually every few minutes that the MDS would turn on the 4 dead cylinders for 5-10 seconds to warm them up and then turn them back off. At least that is what it did on my '06 R/T.
That's true. But when coming off a long MDS run, there is still significant temperature differential in the heads and unless the car sits idling for a while before shut down (MDS is off when idling), the MDS cylinders are substantially cooler that the non-MDS ones are. Short stop and restart and the seats could drop since the seat shrunk in diameter vs. the head pocket (not many, but some did) because the aluminum head equalized temperature faster than the seats did.

This is why the earlier heads had a risk of dropping valve seats. The earlier heads used simple pressed in seats but later design included designed "pins" to retain the seats so the issue went away.
 

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The short answer is that if you have an MDS engine built after 2009, the only reason to turn off the MDS is if you want to...not because you are risking the engine life.
That sounds as though it's suggesting that all the gen one except the last year are at risk?
 

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This is generally correct. The issue with MDS and dropped valve seats mostly was limited to the '06-'07 cars and even then, the numbers weren't huge. No more that about 60 cars have been reported across the various Forums with the issue. Given that the Forums have tens of thousands of members (over 70k members here alone) and that hundreds of thousand of vehicles were made in those years with MDS, the incidence rate is extremely low.

The hypothesis is that the uneven heat within the heads caused by long runs with the MDS on resulted in a sudden change after a short stop and restart (usually after refueling) that caused the seats to drop due to the thermal differential in the head between the aluminum mass and the valve seat.

By 2009, the head manufacturing process was changed for the valve seats and I've never seen any of that year or up have any issue with the valve seats dropping. Today both the 5.7L and the 6.4L use the MDS technology and there haven't been any reports of continued problems.

The short answer is that if you have an MDS engine built after 2009, the only reason to turn off the MDS is if you want to...not because you are risking the engine life.
I know this is 6 years ago but you mentioned 2006-2007 and then anything 2009 and up is safe. What about 2008? Is that lumped into the same group as 2006 & 07?
 

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What about 2008? Is that lumped into the same group as 2006 & 07?
Gen3 Hemi engine (5.7L) was redesigned/updated for 2009 (Eagle engine). 2009+ model years have the improved Eagle engine. So answer to your question is "yes" ... 2008 is in the same group as previous model years.
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