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Originally Posted by JosephA
I could be wrong, but the 6.1 in the Challenger came with MDS, but was unavailable for the 6.4 Hemi until about 2011. So I believe the first one was an 6.1 MDS engine which became available in 2009'ish.
The Grand Cherokee I believe also came with MDS around 2005, so the second link posted might have been an MDS engine. I might have missed any comment or post from the provided links wherein they specifically mentioned if their engine was either an MDS or non-MDS engine.
Only the 5.7L during those years had MDS, the 6.1L never had it, it first appeared on SRT's with the 6.4L, but only backed by an automatic.
https://www.auto123.com/en/car-reviews/2012-chrysler-300-srt8-first-impressions/54109/
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It wasn't long ago that Chrysler's 6.1L V8 HEMI engine was considered massive by modern standards; well, think again. For 2012, the SRT8 engine displaces a whopping 6.4 litres (that's 392 cubes for the retro) and belts out 470 hp matched by 470 lb-ft of torque.
Not only does the bigger HEMI create more clout, it does so more efficiently thanks to Chrysler's fuel-saving MDS cylinder deactivation technology.
Also: https://www.enginebuildermag.com/wp-content/uploads/46568ChryslerHe_00000019776.pdf
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All of the 6.1L engines came without MDS so there is only one cam used for them. It has some serious lift, about 0.050 Ì‹ more than the 5.7L, so the lobes are almost as tall as the journals. Chrysler says it has 283 degrees of duration on the intake and 286 degrees on the exhaust at.006 Ì‹ and 50 degrees overlap, so it's pretty aggressive compared to the 5.7L cam.
There is also this 2010 Challenger brochure that notes that only the 5.7L, and only backed by an automatic, is available with MDS. The 6.1L does not have MDS:
https://www.dodge.com/en/pdf/2010_challenger.pdf
Originally Posted by JosephA
I can see your theory as well, and it is sound. And you might be right. But to me, if that were the case, I would have seen lifters failing on Bank 1 and not limited solely to bank 2 (again on my engine). The intake lifter for cylinder #2 was slightly wet, and had minimal chaffing. The MDS intake lifter on #4 was twisted and unlocked, with the locking pin shifted to the left side within the lifter. It was soaked heavily with engine oil. The intake lifter for #6 was also shifted in the unlocked position and its locking pin was off to the side as well (off-center), and it too was soaked in engine oil. Then finally, the destroyed lifter on #8 was nearly bone dry and not even the springs were wet. That thus told me that cylinders #2 and #8 intake lifters were not getting enough oil, meanwhile the 2 MDS lifters (#4 and #6) were soaked in engine oil. So careful examination seems to suggest insufficient oil to the non MDS lifters on Bank 2, while more than ample oil on the MDS lifters (Bank 2). This is why my theory concluded that the reason for failure had to do with the MDS lifters robbing engine oil pressure just on the bank 2 valve train system. I did not mean to suggest that the rest of the engine suffered oil starvation; only the valve train system will likely be impacted when an MDS lifter fails to lock. An unlocked lifter when it should be locked will lead to wasted oil pressure on the specific MDS lifter, and thereby reduce the amount of oil pressure to the rest of the valve train on the same bank. Keep in mind this does not mean that the rest of the engine would suffer oil loss.
I will have to look at the plumbing galley for the hemi engine. I know the oil pump is at the bottom and a tube feeds Bank 1, and a separate tube feeds bank 2. The first valve train to receive oil is from the first cylinder to the last cylinder of the applicable banks. Otherwise, it makes no sense trying to understand why 2 lifters on Bank 2 were heavily soaked with oil, but the other 2 lifters (intake lifters) were nearly dry.
Lastly, I have motored this engine at idle with the valve covers off, and I saw the same results. Oil oozed out near the center of the head on Bank 2 (Passenger side), but nothing on Cylinder 8, and very little on cylinder 2.
At the same time, I can see a valve train issue with soft springs, leading to lifter float, and that of course would cause roller damage. I can only surmise that the reason Chrysler engineers chose to use softer spring loads is to minimize the valve seat stress on the aluminum heads, and also decrease drag in order to enhance fuel efficiency.
I could be wrong, but the 6.1 in the Challenger came with MDS, but was unavailable for the 6.4 Hemi until about 2011. So I believe the first one was an 6.1 MDS engine which became available in 2009'ish.
The Grand Cherokee I believe also came with MDS around 2005, so the second link posted might have been an MDS engine. I might have missed any comment or post from the provided links wherein they specifically mentioned if their engine was either an MDS or non-MDS engine.
Only the 5.7L during those years had MDS, the 6.1L never had it, it first appeared on SRT's with the 6.4L, but only backed by an automatic.
https://www.auto123.com/en/car-reviews/2012-chrysler-300-srt8-first-impressions/54109/
Quote
It wasn't long ago that Chrysler's 6.1L V8 HEMI engine was considered massive by modern standards; well, think again. For 2012, the SRT8 engine displaces a whopping 6.4 litres (that's 392 cubes for the retro) and belts out 470 hp matched by 470 lb-ft of torque.
Not only does the bigger HEMI create more clout, it does so more efficiently thanks to Chrysler's fuel-saving MDS cylinder deactivation technology.
Also: https://www.enginebuildermag.com/wp-content/uploads/46568ChryslerHe_00000019776.pdf
Quote
All of the 6.1L engines came without MDS so there is only one cam used for them. It has some serious lift, about 0.050 Ì‹ more than the 5.7L, so the lobes are almost as tall as the journals. Chrysler says it has 283 degrees of duration on the intake and 286 degrees on the exhaust at.006 Ì‹ and 50 degrees overlap, so it's pretty aggressive compared to the 5.7L cam.
There is also this 2010 Challenger brochure that notes that only the 5.7L, and only backed by an automatic, is available with MDS. The 6.1L does not have MDS:
https://www.dodge.com/en/pdf/2010_challenger.pdf
Originally Posted by JosephA
I can see your theory as well, and it is sound. And you might be right. But to me, if that were the case, I would have seen lifters failing on Bank 1 and not limited solely to bank 2 (again on my engine). The intake lifter for cylinder #2 was slightly wet, and had minimal chaffing. The MDS intake lifter on #4 was twisted and unlocked, with the locking pin shifted to the left side within the lifter. It was soaked heavily with engine oil. The intake lifter for #6 was also shifted in the unlocked position and its locking pin was off to the side as well (off-center), and it too was soaked in engine oil. Then finally, the destroyed lifter on #8 was nearly bone dry and not even the springs were wet. That thus told me that cylinders #2 and #8 intake lifters were not getting enough oil, meanwhile the 2 MDS lifters (#4 and #6) were soaked in engine oil. So careful examination seems to suggest insufficient oil to the non MDS lifters on Bank 2, while more than ample oil on the MDS lifters (Bank 2). This is why my theory concluded that the reason for failure had to do with the MDS lifters robbing engine oil pressure just on the bank 2 valve train system. I did not mean to suggest that the rest of the engine suffered oil starvation; only the valve train system will likely be impacted when an MDS lifter fails to lock. An unlocked lifter when it should be locked will lead to wasted oil pressure on the specific MDS lifter, and thereby reduce the amount of oil pressure to the rest of the valve train on the same bank. Keep in mind this does not mean that the rest of the engine would suffer oil loss.
I will have to look at the plumbing galley for the hemi engine. I know the oil pump is at the bottom and a tube feeds Bank 1, and a separate tube feeds bank 2. The first valve train to receive oil is from the first cylinder to the last cylinder of the applicable banks. Otherwise, it makes no sense trying to understand why 2 lifters on Bank 2 were heavily soaked with oil, but the other 2 lifters (intake lifters) were nearly dry.
Lastly, I have motored this engine at idle with the valve covers off, and I saw the same results. Oil oozed out near the center of the head on Bank 2 (Passenger side), but nothing on Cylinder 8, and very little on cylinder 2.
At the same time, I can see a valve train issue with soft springs, leading to lifter float, and that of course would cause roller damage. I can only surmise that the reason Chrysler engineers chose to use softer spring loads is to minimize the valve seat stress on the aluminum heads, and also decrease drag in order to enhance fuel efficiency.
JosephA said:Maybe this is all the result of flawed lifters from what ever country they were manufactured. But I'm not convinced this is the case because we would see random lifters dropping out all over the engine, and impacting nearly every hemi engine. Thus, I believe this is primarily limited to the MDS engines, and possibly some non-MDS engines suffering failure. But this I am convinced of. So far, all who have upgarded their hemi's to the Comp-Camshaft, Hellcat lifters, oil plugs, and ECM flash, have not had a repeat of camshaft or lifter failure.
If you had a 1 in 10,000 lifter failure rate, you'd likely only have an engine impacted by one lifter, which likely corresponds with the failure rate being observed. Also, it does seem to require a fair deal of mileage/hours before it happens, which, if it was solely due to starvation, you'd think would happen earlier on, particularly since we know it happens on non-MDS engines too, even if not in the same quantity
Regarding the upgrades: Since the failures usually require significant mileage before occurring, how many of those people that have swapped out their parts have since accrued that same amount of mileage? I'm interested to see if any of the HellCat lifters fail once there are enough out there with high miles on them, that'd be a real tell, though the 6.1L failures are pretty [censored] in themselves, as those engines also had billet steel camshafts.
Originally Posted by JosephA
Was it because MDS was deleted? That seems to be the case, IMHO. Then again, it might be as you have suggested....poorly designed lifters using cheap parts. If it had anything to do with the valve springs, I would assume we'd see more lifter failures even with the upgraded lifters and camshafts. So far, I have not read of any upgraded engine failures.
Joe
It's possible it's also a combination of weak springs and needle-bearing lifters that aren't tolerant of anything resembling float. Heck, if we toss a marginal oil delivery system in there it's a potential recipe for a perfect storm that may require all three things simultaneously to propagate. It's definitely an interesting topic.