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Timing chain failure on the Dodge Challenger

1M views 6K replies 443 participants last post by  Mopar Frank 
#1 · (Edited)
I have been finding many reports of the timing chain breaking on the Dodge Challenger, mostly in the 5.7L Hemi engines. The timing chain breaks in most reported instances around the 35K-40K mile range.

Once the timing chain breaks, the end result is usually the valves smacking the pistons which bend the valves, damages the pistons and leads to catastrophic engine failure. This often requires a new long block.

How many of you have had the timing chain break? How many miles on the car when when it happened? and what was your experience in getting it repaired?

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Known instances of the timing chain breaking on the 5.7L Dodge Challenger just in this forum alone in the past few months:

1. 06/27/2011 -- mileage not mentioned -- ... come to find out the timing chain broke ...

2. 07/19/2011 -- 85,000 miles -- ... and the timing chain broke...

3. 09/27/2011 -- 33,385 miles -- 2009 R/T Motor Broke

4. 11/23/2011 -- 38,000 miles -- Club member's car. Broken timing chain. Car in shop for over two months.

5. 12/07/2011 -- 34,000 miles -- I found this thread the hard way...

6. 12/19/2011 -- 22,600 miles -- 2010 Challenger - Timing Chain Breaks...

7. 01/21/2012 -- 60,000 miles -- Engine went..........

8. 02/02/2012 -- 38,000 miles -- 2009 Challenger R/T lost a second motor .. (Second occurrence. See #3 above. 4,000 miles on new motor).

9. 03/08/2012 -- 50,000 miles -- BLOWN ENGINE 50,000 miles

10. 03/23/2012 -- 14,000 miles -- ... my timing chain snapped

11. 04/04/2012 -- 53,500 miles -- My timing chain just broke today ...

12. 04/16/2012 -- 46,000 miles -- Mine is in the shop with a broken timing chain...

13. 04/27/2012 -- 31,000 miles -- My chain broke back in December of 2011 ...

14. 05/22/2012 -- 37,000 miles -- Here's another 2010 Auto R/T with a broken timing chain! ...

15. 06/13/2012 -- 40,257 miles -- I too have a broken timing chain ...

16. 06/23/2012 -- 38,485 miles -- Guess I can be added to the list ...

17. 06/26/2012 -- 38,500 miles -- Just happened last Saturday ...

18. 08/02/2012 -- 59,134 miles -- ... all of a sudden Bam the engine shuts down

19. 08/03/2012 -- 38,000 miles -- I had this happen at 38000 miles, 2010 R/T Auto

20. 08/08/2012 -- 27,000 miles -- The timing chain on my 2010 R/T just broke ...

21. 08/10/2012 -- 59,300 miles -- ... timing chain broke again. (Third occurrence. See #3 and #8 above. 16,000 miles on new motor).

22. 08/10/2012 -- 63,000 miles -- ... timing chain broke cruising at 70mph on the highway

23. 09/03/2012 -- 40,000 miles -- ... while driving to dallas my timing chain broke

24. 09/11/2012 -- 24,000 miles -- Welp - chalk up another one ... (first 2011 to be reported here)

25. 09/21/2012 -- 31,100 miles -- This just happened a few days ago ...

26. 10/10/2012 -- 42,559 miles -- Well it's looking like I'm the latest timing chain victim ...

27. 10/24/2012 -- 65,000 miles -- ... driving on the highway 65MPH and "Pop goes to weasel"

28. 11/18/2012 -- 40,000 miles -- Mine just broke...2010 mopar 10, no mods, auto ... (first to break not at highway speeds)

29. 11/19/2012 -- 39,000 miles -- just got another 2010 with 39000 in today ...

30. 12/04/2012 -- 40,000 miles -- The timing chain on my 2010 Auto RT broke last Friday ...

31. 12/09/2012 -- miles pending -- ... R/T not running at the moment timing chain broke ...

32. 12/11/2012 -- 27,000 miles -- ... cruising on the interstate at 70, MDS on, when suddenly loss of power ...

33. 01/03/2013 -- 58,000 miles -- ... the dealer has confirmed that I did have a timing chain failure.

34. 01/22/2013 -- 40,000 miles -- It has been confirmed I as well did have a broken timing chain

35. 01/22/2013 -- 43,000 miles -- 2010 R/T, 5-speed auto with mds. No mods at all.

36. 02/22/2013 -- 52,000 miles -- ... it happen to me this weekend ...

37. 04/15/2013 -- 55,000 miles -- I have now become victim to a failed timing chain

38. 04/20/2013 -- 73,000 miles -- cruising at 65 mph, in MSD, engine 'shut down'

39. 05/13/2013 -- 66,000 miles -- lost it on the interstate doing 73 in MDS

40. 05/20/2013 -- 56.616 miles -- ... on the freeway headed to work in the rain and Wham

41. 05/24/2013 -- 28,000 miles -- the chain went on the highway at 70+ mph

42. 06/07/2013 -- 88,256 miles -- ... driving down the highway heard a loud pop ...

43. 07/01/2013 -- 52,000 miles -- Timing chain broke on freeway ...

44. 07/23/2013 -- 54,057 miles -- Was in a canyon going uphill at about 55mph ... (claims MDS not engaged)

45. 07/26/2013 -- 49,000 miles -- Cruising along 65 mph engine stalled.

46. 08/10/2013 -- 22,281 miles -- I wish I found this topic sooner

47. 09/17/2013 -- 40,091 miles -- driving 74 mph in cruse control just died ...

48. 10/04/2013 -- 68,000 miles -- Add another one to the list OMG.

49. 10/22/2013 -- 89,000 miles -- Timing chain went on my 09 Challenger

50. 11/13/2013 -- 55,320 miles -- I had hoped I would never be posting this message ...

51. 11/13/2013 -- 42,342 miles -- Just got up to highway speed Bam Powerloss ...

52. 11/21/2013 -- 53,000 miles -- Add me to the list of failures ...

53. 11/27/2013 -- 73,000 miles -- I was cruising at highway speeds (70 mph), in MDS

54. Recall initiated, see below.

Remember, these reports are from this forum alone. Real world numbers are greatly increased.

The things in common when the timing chain breaks so far are:

1. MDS is activated (auto trans., so 6-speed are excluded)
2. Traveling at freeway speeds (or coming off of freeway)
3. 2009-2011 model years affected so far.
4. Limited to the 5.7L motor so far
5. Dodge Challenger only

Things ruled out thus far:

A. 6-speed manual transmissions not affected
B. Other 5.7L vehicles not affected, i.e., Charger, 300, Ram truck
C. New guide shoe (white color) has also failed (see #8 on list of failures)
D. New crate motor has also failed (see #3 and #8 on list of failures)
E. Both stock and mod cars affected
F. Both stock tune and Predator tune (with MDS turned on) affected
G. All oil change intervals affected, i.e., 3,000 miles, 5,000 miles, etc.
H. All types of oil affected, i.e., both synthetic and conventional oil

* Author's notes (last updated 10/28/13):

(1) When I created this thread, I was so taken back by a timing chain failure happening and discovering at least a half dozen similar occurrences, that I attempted to discover if anyone here had experienced a timing chain failure and what their dealership experience was. I got a lot of adverse feedback along the lines of "alarmist" and "chicken little" and other name calling, including some from dealerships and master mechanics, as can be seen in just the first few hundred posts below. Many attempted to derail this thread by taking it off-topic on many, many occasions. Some are still out there promoting denial of the issue. Still, the problem remains, it is real and it continues to plague fellow Challenger owners.

(2) The timing chain concern can be alleviated by disabling MDS (a band-aid solution not a fix). All but one recent report have shown that MDS was engaged and the car was traveling at freeway speeds. You can prevent MDS from being activated by switching into manual mode while driving on the freeway. You can read How to use the Autostick feature and manual mode here. You can also use a tuner to disable the MDS feature, but be forewarned, if the dealership discovers your use of a tuner on the car, you are in for a fight to get the repairs done under warranty.

(3) Chrysler is aware of the issue and has been monitoring this thread for some time regardless of they might tell you. In addition, many people have already telephoned customer service and have written to Chrysler directly. But, even without all of that, you don't have timing chains, tensioners, heads and short blocks rolling out of the warehouse in the numbers that they have without raising some internal red flags of a potential issue.

(4) Talks of running off to court and filing a lawsuit over this issue are misguided. Your warranty specifically states that you MUST first submit the matter to arbitration. Any lawsuit would be immediately dismissed, and now you are out the filing fees.

(5) When I first created this thread, the weekly parts demand for timing chains was at about 15. It is currently hovering around 35 at the moment.

(6) Chrysler has switched from the black tensioner and guide to white (supposedly stronger) and then to an aluminum tensioner and guide with a plastic face plate (the current part). Both black and white guides have failed. No reports of the aluminum failing yet but they are relatively new first showing up in mid-2013 R/T's.

(7) The exact cause of the timing chain failure is still unknown. In fact, it may never been known. There are just too many factors involved to isolate the problem, and if we haven't discovered the cause in over 350,000 page views, how can we expect Chrysler to? While there is a lot of speculation as to the exact cause, which seems to go round-and-round every few hundred posts, it is all just that -- speculation. What we do for for certain is that MDS is playing a part in the timing chain failures.

(8) Special shout outs to Desert Bum, Hal H, hmk123, Force10, 19johned53, and the nameless many who have helped to keep this issue real and on topic. Your comments are appreciated.

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* Author's notes (last updated 02/12/14):

Customer Satisfaction Notification P01
Engine Timing Chain and Chain Guide
Models
IMPORTANT: Some of the involved vehicles may be in dealer used vehicle inventory. Dealers should complete this repair on these vehicles before retail delivery. Dealers should also perform this repair on vehicles in for service. Involved vehicles can be determined by using the VIP inquiry process.
Subject
Repair
2009-2012 (LC) Dodge Challenger
(LD) Dodge Charger
(LX) Chrysler 300
NOTE: This recall applies only to the above vehicles equipped with a 5.7L Hemi engine (sales code EZD or EZH), automatic transmission (sales code DGJ) and rear axle ratio 3.06, 3.73 or 3.92 (sales code DMP, DME or DMH) built from August 04, 2008 through July 10, 2012 (MDH 080406 through 071008).
The engine timing chain guide on about 50,800 of the above vehicles may fracture. A fractured engine timing chain guide could cause the engine timing chain to break. A broken engine timing chain will result in severe engine damage.
The engine timing chain, timing chain tensioner and timing chain guide must be replaced.
Customer Satisfaction Notification P01 Engine Timing Chain and Chain Guide Page 2
Part Number Description
CBPRN291AA Engine Timing Chain Package
Each package contains the following components:
Quantity Description
1 Chain, Engine Timing
1 Guide, Engine Timing Chain
1 Tensioner, Engine Timing Chain
1 O-ring, Oil Pick-up Tube
1 Gasket, Engine Timing Cover
NOTE: Order two heater tube O-rings separately listed below for each repair.
Part Number Description
53013736AA O-ring, Heater Tube (order two per vehicle)
Each dealer
to whom vehicles in the recall were assigned will receive enough Engine Timing Chain Packages to service about 5% of those vehicles.

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Recall type:

Customer Satisfaction Notification - Customer Satisfaction Notifications are preventive in nature and involve warranty or customer satisfaction issues such as non-safety repairs. Chrysler will correct the problem, at no charge, even if the vehicle is out of warranty and you are not the original owner.

You can check if your vehicle is subject to the timing chain issue recall (or any other recall) by visiting the Chrysler website and entering your vehicle's VIN number. Visit: http://www.chrysler.com/en/mobile/webselfservice/

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We really want to thank everyone who wrote us, (Pietro), with their timing chain concerns. The engineering team has completed their work and the following statement has been released. If there are any questions, reach out to us on this forum as opposed to sending an email as that will be quicker.

Chrysler Group is launching a customer-service action to bolster timing-chain system durability in certain cars equipped with 5.7-liter HEMI® V-8 engines.

The decision follows an extensive investigation to determine the precise issue and appropriate remedy.
The investigation discovered the engine’s fuel-saving cylinder-deactivation technology may cause an adverse interaction with the timing-chain system. (Chrysler Group is unaware of any related injuries or accidents.) As a result, the Company will replace – at no cost to customers – the timing chains, tensioners and guides in certain vehicles built between Aug. 4, 2008 and July 10, 2012.

Affected are certain model-year 2009-2012 Dodge Charger and Chrysler 300 full-size sedans, and Dodge Challenger sport coupes. The scope is limited to vehicles equipped with 5-speed automatic transmissions and axle ratios of 3.06, 3.73 or 3.92.

Beginning this month, Chrysler Group will contact affected customers with instructions to schedule service appointments with their dealers.

Chrysler Group greatly appreciates the patience demonstrated by its customers while this issue was under investigation. The Company also values and shares the passion expressed on these pages by customers and fans alike.

Thanks,

DodgeCares
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Article: Timing Chain Failure on the Dodge Challenger – Ground Zero

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2
#271 ·
lol ravenx
 
#273 · (Edited)
Ughhhh again. I worked on Chrysler Dodge Jeep stuff for 18 years and there MIGHT have been a total of less than 10 timing chain failures I saw in that 18 years on ALL cars. Now the dealer I recently worked at has seen 3 in the past few months on 5.7L MDS CHARGERS!!!!! I say there is a problem.

Havent seen any failures on the 05-08 NON EAGLE 5.7L's have we. :)
 
#276 ·
Luke,

What, exactly, is the difference between old/new?? I've lost track with all of the pages of threads, so if you've already posted pics then forgive me, but if you haven't, WOULD YOU PLEASE? Also, when was the change from old to knew done - what model year(s) are affected?
 
#277 ·
What has been everyone's experience in getting this fixed? Yesterday the dealer #2 confirmed it was a timing chain break (as dealer #1 had previously diagnosed), but they also found a leaking water pump. They told me the car would be fixed today. I asked them yesterday what about the valve and piston damage? They insisted that they didn't need to check for that. Guess what? After they put everything back together today and start the car they found out it does have valve damage! They're opening it up now to see what further damage has been done. He also says the car won't be ready till at least Tuesday and that my car rental is only good for 5 days (today is day 4 since I didn't get the rental until Monday evening despite the car dying on Sunday afternoon). I called Chrysler HQ to complain and ask for them to extend my rental but all they could do was forward my case info to the rental department but they may not be getting back to me right away.

Has anyone else gotten a car past 5 days?? How did you handle that??
 
#281 ·
anyway to get a new revised tensioner put in before it breaks and does more damage?????
 
#293 ·
I have taken a good hard look at the tensioner, guide, and chain, and between me and my machinist we are almost certain the guide shoe went causing the chain to break one link while the engine continued to run normally. The remaining link finially gave up at some point thus wiping the whole thing out.

I have attempted to re-create the guide shoe as it should have been in one piece. Take notice of the thinnest section, that is where it broke. The tensioner was in one piece, had it not been for the timing chain falling off it would be intact.

Look closely at the two sections of guide I am holding together. The wear mark closest to my thumb is wore unevenly, the upper half has severe grooving, while the lower half does not show that amount of wear. This would indicate the guide broke, and the upper half remained in contact with the broken link, causing the severe wear pictured. The very lowest piece of the guide, the part that fastens to the block, shows the exact same wear pattern as the broken piece.

Now look at the chain. The camera would not focus as close as I would have liked but you can easily make out the broken links. Notice how the one broken link is shiny?? that is the link that went first, it polished itself smoothly rubbing on what was left of the guide. the other link held on for dear life, but it eventually failed. Download the picture and zoom in on the links.

BTW.... my machinist is one of the finest engine builders you have never heard of.....
It's not the tensioner, it's not the chain, it's the guide shoe. Right? Is this a part that can be upgraded? If so, how easy/difficult would it be to do it?

Great information!
 
#294 ·
It's not the tensioner, it's not the chain, it's the guide shoe. Right? Is this a part that can be upgraded? If so, how easy/difficult would it be to do it?

Great information!
You are correct, you are looking at the guide shoe. The tensioner is also a big piece of ****e, but it didn't break, it fell apart when the chain went away. The piston and spring that apply the tension landed in the oil pan.
 
#284 ·
Or... trade it in for a 6 spd! :thumbsup:
 
#286 ·
ravenx ... you my freind are making sence ..... but what if its everything your saying , but based on running high rpm's for a pro longed time mixed with the abrubt hits of the MDS .... My question is this ... if the timeing chain broke itself ... would it then snap the tensioner ..... cause if the tensioner broke , i could see losing the chain .... its a question only .. i am not a mechanic in any way ... i call my self a parts changer .. i can change parts but i cant diagnose a problem unless its a scenario iv had before or helped fix before ... I have 30k on my car now and do not want to tear it ... now i have had my MDS off more than 90% of the time i have had the car . since about 2 mnths after i bought it and got my predator .. its been off, but now i drive this car like i stole it ... so definately sounds like its the MDS to me also .. JMO
 
#287 ·
... My question is this ... if the timeing chain broke itself ... would it then snap the tensioner ..... cause if the tensioner broke , i could see losing the chain ....
If the timing chain broke, it would, because it's now free, more than likely whip around and take out the tensioner. So, it would be hard to determined which came first, the chicken or the egg. But if the tensioner broke first, allowing the timing chain to flap around, then the cam would also be a bit free to rotate off kilter causing the car to run rough at least for a brief moment before the timing chain failure, and that hasn't been reported. Also, the damage to the pistons would, IMHO, be more extensive if the valve train was still moving but out of sync due to the cam moving off kilter and thus opening and closing valves at the wrong moment.

Of course, that's just my opinion. Like I said, it's still anyone's guess as to what the exact cause is.
 
#289 ·
I would bet the dealer did know the valves would probably need replacing. Sounds as if the dealer was hoping they could get lucky and short cut the job; thus making more profit on the warranty repair.

I would have gone ape sheet.
 
#290 ·
ravenx ... again you make sence of my skeptisism ..... and in your words ... i understand and does seem to maybe be the chain first ..... and chicken before the egg was a perfect analogy ... lol ... this sucks ... but my MSD is still off .. so we will see what happends .. hopefully if something does i will still be under warranty
 
#296 ·
I wonder if it was really necessary for the Hemi valvetrain to be an "interference" design?...and if so, was it a cost-cutting measure to not cut reliefs into the pistons, or is it that they are hyper-eutectic pistons which makes machining impractical?

You'd think Dodge would have put more safeguards in, to better contain a situation from going catastrophic? Remember a time when domestic design engines were a staple in reliability as far as the cam drive chain being the last thing to ever break, while import engines clearly had an Achilles heel with rubber timing belts that snapped with certainty and fatality given their typical interference valve clearance design? Now, many import engines come with everlasting chains, and we are stuck with a chain drive that is unusually prone to self-destruct and take the whole engine with it? That's not so cool!

You can argue that the failures are very low by percentage, but the fact remains that chain failure should be utterly unheard of, altogether, for the very reason that a chain is used for the design in the first place.
 
#323 ·
I wonder if it was really necessary for the Hemi valvetrain to be an "interference" design?...and if so, was it a cost-cutting measure to not cut reliefs into the pistons, or is it that they are hyper-eutectic pistons which makes machining impractical?

Now, many import engines come with everlasting chains, and we are stuck with a chain drive that is unusually prone to self-destruct and take the whole engine with it? That's not so cool!
With the high CR of these engines, the combustion chamber is smaller, placing the valves closer to the piston (smaller quench areas are designed to facilitate more complete combusion/lower emissions). The other approach is the piston tops are taller/thicker to boost CR as well.

There's some valve relief for normal operation, but when the valvetrain is out time (chain jump or outright failure), its hard to design around that.

Otherwise a non-interference engine is compromised to a non-interference design for a relatively rare occurrence of a timing chain failure.

Even European and Asian cars with OHC and chain drives need attention - the chain guides and tensioners can wear or fail - and they're not cheap to deal with.

The older MB OHC/DOHC V8s can run about $2k to deal with the timing chain replacement and tensioners, guide shoes, etc. And that's the preventative maintenance, not a catastrophic failure.
 
#297 ·
From what I have read via chrysler training materials, VVT was invented for the sole purpose of deleting the EGR valve. The fat, flat torque curve was an added bonus....

VVT is not the problem in my opinion, its the MDS. If you have ever built an engine with a roller cam think of it this way.....

When you adjust the valves on the first cylinder, there is a lot of spring pressure resistance when the cam comes up on the ramp, normalizes when the lifter peaks, and on the way down, the spring pressure pushes the cam lobe to the point were it can almost, and sometimes does roll the motor over by mere spring pressure.

When all the valves are adjusted, the motor turns over with an equal amount of resistance, placing an even amount of pressure on the cam.

Now MDS comes into play....
Take away eight lifters (four cylinders) and what do you have??? A ton of harmonics due to uneven pressures being placed on the camshaft, which would most certainly tranfer to the timing set. To add, the camshafts in the 5.7 are..... wait for it.......

Hollow.

In my opinion, that is why the timing chain failure.
 
#298 ·
The camshaft harmonic vibration may be causing a condition called cordial whip.

This condition is easily to witness........

Open the hood of any single belt driven A/C compressor vehicle, not a serpentine setup. Look at the belt with the A/C off...... nothing to really see.
Now turn the the A/C on and again look at the belt. On the slack side the fanbelt is violently pitching, yet there is a constant load on the belt.

What you have witnessed is the hamonics from the piston assy in the compressor being transfered into the fanbelt. All the start stop and uneven pressures cause the cordial whip condition, same as MDS??

My two cents anyway.......
 
#299 ·
So we know the tensioner is spring loaded, that means it can apply tension to the chain, but the vibration of the chain can push back on the tensioner causing it to vibrate as well.
Now if the tensioner was solid, it would severly limit the amount of chain vibration. Fluid will not compress, so if you used oil pressure, combined with spring pressure it would allow the tensioner to adjust for wear and start ups while oil pressure would "lock up" the tensioner and would not be influenced nearly as much from the vibration. The problem being the vibration is still there.............

maximum vibration occurs at a certain RPM, that condition is called resonance frequency. An example we have all witnessed at some point is tire balance. Going down the road at 50mph is nice and smooth...... pick up the pace to 60mph and here comes the vibration( resonance frequency) speed up to 75mph and the vibration goes away(out of resonance frequency) crank it up to 120mph, and the vibration is back, only waaay worse then it was at 60mph. There is an explination on why the vibration effectively doubles at higher speeds but I think everyone will get he point I am making.......

Serious race engines use a belt drive system like a Jesel or Comp. One of the main reasons for doing so is to help absorb valve train vibrations which we have discussed in an earlier thread.
 
#300 · (Edited)
I think the "absorb valvetrain vibrations" part is addressed at least in part by the modern crankshaft damper on the crank pulley.

Your thoughts on resonance in the adjuster and chain are compelling, nonetheless.
 
#304 ·
I think the "absorb valvetrain vibrations" part is addressed at least in part by the modern crankshaft damper on the crank pulley.

Your thoughts on resonance in the adjuster and chain are compelling, nonetheless.

Randy,

You are 100% right on the damper absorbing vibrations. I did a poor job of an explination on the topic. The balancer absorbs both torsional and radial vibrations emitting from the crankshaft, as to not transfer those vibrations into the valve train. Big horsepower blown alky/nitro do not use a balancer, its just a blower hub and they rely on the blower belt and timing belt to suck up whatever vibration they can.

The pictures attached are of a 788 cubic inch Pro-Mod engine that the balancer either went away or the bolt came loose, impossible to tell with any certainty.....
 

Attachments

#301 ·
Update from the dealer on my car. They finally discovered several pistons/cylinders were damaged so they put those parts on order today. They said they did some sort of cost analysis and sent it to Chrysler and Chrysler decided that the dealer needed to repair the parts instead of getting a new engine block. :(

Anyone else have similar experiences?
 
#302 ·
Update from the dealer on my car. They finally discovered several pistons/cylinders were damaged so they put those parts on order today. They said they did some sort of cost analysis and sent it to Chrysler and Chrysler decided that the dealer needed to repair the parts instead of getting a new engine block. :(

Anyone else have similar experiences?
Glitch,

I didn't physically take my car in on purpose, I did not want a carfax hit on it, plus 99.99% dealer technicians are joke. The car had 61K when this all went down, so i went in to discuss repairs with the service manager. Do to the fact it was a high mileage car, I was told it was Chrysler's option whether they used a new vs. re-man or have the dealership rebuild it.

It was truly a waste of breath, I explained of the cars potential collectors value, matching numbers, yada, yada, yada. They heard none of it. Truth be told it is just another pain in the @ss warranty claim that whoever it gets assigned to will surely loose his @ss on flat rate time. Challenger, smallenger, it just a car to them.

I do not want to worry you any more than you have already suffered, however if the tech did not understand of the potential piston/cylinder wall damage, do you trust him to rebuild it???

There are some techs that are at the genius level, but man o man you could count them on one hand.

A few things to consider asking the shop..... replacing rods and pistons (thet come as an assembly) will/could/might throw off the factory balance. Are they going to send out the crank and have it rebalanced? You state they replaced the valves, did they do valve job, check for the guides being cracked, or just lap the seats and call it good... Hopefully, (but I doubt it) they didn't use a scotchlock pad on the heads.... it a common short cut, but man does it screw up the cylinder head surface. Tell them not to go near your engine with that stuff......
One last thing to consider... do not, by all means have the dealership or machine shop the block goes to shot-a-brate the block. You will never, repeat never,get those little metal BB's out of all the nooks and crannys.... especially on a MDS/VVT block. Weeks, months later all of a sudden your oil pressure goes away due to one or two of those metal BB's getting pushed thru the oil passages....

Good luck my friend.....
 
#305 · (Edited)
"VVT is not the problem in my opinion, its the MDS."

If that is true, the 6-speed stick cars should not be breaking chains, aye? I'm gonna go look for geardrives for the 5.7 in a minute. On another note, I remember how pleased I was years ago when my AMX jumped time at around 100k on its original plastic tooth chain sprocket & I found that the pistons smacked the valves & bent pushrods only. The "dogleg" amc engines are a great design, I don't care what anybody says. A simple bolt-on build with the right pieces & standard race-prep gets you over 500 HP, & it's probably half the weight of a BBC or an iron hemi.
 
#306 ·
From the MOPAR Performance site, an aluminum block WITH geardrive mounting boss, I wonder if the factory iron blocks have that cast into them???

Hemi Gen III Aluminum Blocks are 100 pounds lighter than 6.1L production cast iron blocks! They are designed to accommodate all parts from a 6.1L Hemi Gen III engine.

Features: · Lightweight aluminum gives added performance in more ways than one - better acceleration, braking, vehicle dynamics, weight distribution, you name it. Lighter is better. · Water jackets have been completely re-designed to accommodate a Siamese bore. Extensive Computational Fluid Dynamics (CFD) studies have been performed to balance thermal conditions for consistent and reliable performance. · Crankcase clearance designed for a 4.125" stroke crankshaft. A 4.250" stroke will fit with machining around the oil drain backs. · The main bearing supports and the bottom end of the block have been completely redesigned for the additional strength required for a forced induction 440+ cubic inch motor. · 8620 HR billet steel main caps with four-bolt center caps beef-up the bottom end for severe performance applications. · Capable of supporting a dry sump package for reduced windage and to allow more engine installation options, including lower vehicle center of gravity. · Camshaft bearing support area increased to permit the use of a 60 mm roller bearing, if desired. · Lifter bores can be opened to 1.060" for a bushed-style lifter. · Additional boss in the front timing chain area for an idler (double roller chain). Additional boss for a front gear drive, plus attachments for a front motor plate. · All HEMI Gen III dress items fit Gen III Aluminum Blocks (front cover, oil pan, oil filter mounting. Front End Accessory Drive (FEAD), etc.)

P5155507 Block, Aluminum, 426 Hemi, Gen III, Bored at 4.125", Can Be Bored Up to 4.155" P5153897 Block, Aluminum, 6.1L Hemi, Finished Bored at 4.055"

P5153898 Block, Aluminum, 6.1L Hemi, Semi-Finished Bored at 4.114". Can be Bored Up to 4.185"

P5155630 Block, Aluminum, Hemi Gen III, Semi Finished Builder's Special
 
#308 ·
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