# Another Flywheel



## MRO1791 (Sep 2, 2016)

johnmo said:


> I think I may have some further insight into why GM is dropping manual transmissions, especially on the diesel: the flywheel.
> 
> The dealer hasn't given me the official diagnosis yet, but I'm pretty sure my flywheel has broken now for the second time in 10 months and 27k miles.


Wow, what are the symptoms? I have a 2018 Manual Diesel. So far all good, but only 2400 miles. 

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## johnmo (Mar 2, 2017)

With the first one I never noticed anything. The mechanic caught it during an oil change. He said it was really noisy. I'm usually tuned in pretty well to noise and vehicle behavior, but I never caught it. I think maybe if I did more driving with the windows open I might have heard it.

With this one, I heard metallic popping noise as I was pulling away from a gated parking entrance where I have to open the window and swipe a badge. I was also hearing a noise that sounded like a stuck lifter, but it was in a very narrow throttle range under light load. If that had been the only thing, it might even be dismissed as diesel clatter, but I didn't like the sound of it even in a diesel.

The big serious symptom was heavy driveline shuddering on starting out from a stop and a lighter shudder on throttle transitions from no load to light load. Heavy throttle settled it down, but light throttle made it feel like it was out of balance somewhere in the driveline.

Still waiting to get the final diagnosis from the dealer. When I described to the service writer, he advised to have it towed to the dealership rather than driving it.


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## IndyDiesel (May 24, 2015)

johnmo said:


> With the first one I never noticed anything. The mechanic caught it during an oil change. He said it was really noisy. I'm usually tuned in pretty well to noise and vehicle behavior, but I never caught it. I think maybe if I did more driving with the windows open I might have heard it.
> 
> With this one, I heard metallic popping noise as I was pulling away from a gated parking entrance where I have to open the window and swipe a badge. I was also hearing a noise that sounded like a stuck lifter, but it was in a very narrow throttle range under light load. If that had been the only thing, it might even be dismissed as diesel clatter, but I didn't like the sound of it even in a diesel.
> 
> ...


I have been thinking about a manual diesel, what a bummer. Would be an expensive fix outside of warranty. Flywheel should last 250k not just a few miles


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## Robby (Mar 1, 2013)

Are these using a 'Duel Mass' flywheel?

Rob


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## obermd (Mar 3, 2012)

Robby said:


> Are these using a 'Duel Mass' flywheel?
> 
> Rob


Wouldn't that be "dueling mass" flywheel, where one mass shoots the other?


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## jblackburn (Apr 14, 2012)

You'd have think they'd have redesigned the flywheels to handle the higher torque of a diesel motor, but it's been somewhat common on the 1.4T's too. Actually, I thought this was why they switched to using the GMPP clutch and flywheel in the 2015+ models - supposed to be a more robust design. I would have thought that carried over to the Gen 2's along with the transmission.

Yeah, they are dual mass flywheels, designed to smooth out the vibrations of the thrashy little motors.


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## MRO1791 (Sep 2, 2016)

DMF.. hmm. On the turbo diesel register for Cummins diesel pick ups many with the manual G56 transmision have ditched the DMF in favor of a classic standard flywheel... I wonder of there is an after market option for Cruze like there is for that G56 in the Cummins diesel. So far my G56 DMF has been fine, but I do have low miles, not even 50k yet.

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## BobJacobson (Jan 10, 2018)

15k miles on mine and no issues so far.


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## Jacque8080 (Oct 31, 2017)

I'm at 2400 miles without issue. Well after it warms up, I'll have a few intentionally firm shifts getting onto the interstate or something.

Is the Aisin transmission unique to the diesel? I think the 1.4 guys have an M32 instead.


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## johnmo (Mar 2, 2017)

MRO1791 said:


> DMF.. hmm. On the turbo diesel register for Cummins diesel pick ups many with the manual G56 transmision have ditched the DMF in favor of a classic standard flywheel... I wonder of there is an after market option for Cruze like there is for that G56 in the Cummins diesel. So far my G56 DMF has been fine, but I do have low miles, not even 50k yet.


Similar story with Volkswagens. My TDI Jetta had a DMF on the DSG transmission and there were enough stories about them breaking to warrant awareness of it as an issue. There was a lot of chatter in the VW TDI community about switching to traditional flywheels too, though I don't know how many actually did it.


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## johnmo (Mar 2, 2017)

IndyDiesel said:


> I have been thinking about a manual diesel, what a bummer. Would be an expensive fix outside of warranty. Flywheel should last 250k not just a few miles


I bought an extended warranty and the dealer I bought from includes a lifetime powertrain warranty, so I don't expect to ever pay for a flywheel.

However... I suspect there are limits to what the warranty companies will put up with. I haven't checked into the fine print (beyond the requirement to have all work performed by an ASE mechanic) but there would have to be some kind of out for them. I can't imagine any warranty company happily covering a flywheel or two every year for 10 years.


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## jblackburn (Apr 14, 2012)

johnmo said:


> I bought an extended warranty and the dealer I bought from includes a lifetime powertrain warranty, so I don't expect to ever pay for a flywheel.
> 
> However... I suspect there are limits to what the warranty companies will put up with. I haven't checked into the fine print (beyond the requirement to have all work performed by an ASE mechanic) but there would have to be some kind of out for them. I can't imagine any warranty company happily covering a flywheel or two every year for 10 years.


I would set the car on fire if I had to deal with that every year.


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## johnmo (Mar 2, 2017)

jblackburn said:


> I would set the car on fire if I had to deal with that every year.


:lol:

I really like the car. But... this is the single worst experience I've had with any vehicle -- new or used -- I or anyone in my family have ever owned.


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## MRO1791 (Sep 2, 2016)

johnmo said:


> [emoji38]
> 
> I really like the car. But... this is the single worst experience I've had with any vehicle -- new or used -- I or anyone in my family have ever owned.


Have you heard of any others? I'm wondering if there might be something on your car that is causing it.. or the original had a defect and then the screwed up the replacement somehow. As much as the Cummins forums complain about DMF, it doesn't seem to always be a problem, and it's also likely often due to performance tunes and oversized tires etc. 

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## johnmo (Mar 2, 2017)

MRO1791 said:


> Have you heard of any others? I'm wondering if there might be something on your car that is causing it.. or the original had a defect and then the screwed up the replacement somehow.


Other than jblackburn's comment about it being a not-uncommon issue on the 1.4 gassers, I haven't heard of any others. I think there are only a couple of others here with the miles I have and I can't remember if they are MT or not. My first flywheel broke around the second oil change in the 10k neighborhood and there are certainly a few more folks with that mileage.

Still waiting to hear anything back from the dealer. There's a case open with GM since I have two different things that have broken twice now on the car -- the head unit and (suspected) flywheel.

I sure hope it's not me. I'm a boring old guy with a long highway commute.


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## jblackburn (Apr 14, 2012)

There was someone on the Facebook group (Phil Bidwell I think?) that had one go out on a diesel 6MT too at relatively low mileage.


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## BobJacobson (Jan 10, 2018)

Would the flywheel fall under the powertrain warranty or would they consider it a wear and tear item like a clutch?


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## johnmo (Mar 2, 2017)

It's not the flywheel.

It's a bad fuel injector. That kind of makes sense because it did run kind of like it was short a cylinder, but not consistently. Different throttle positions seemed to clear it up. It was probably throwing a code, but where I already had a CEL for the NOx sensor, I didn't suspect another engine code.


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## MRO1791 (Sep 2, 2016)

It looks like my DMF has failed at 12K. I'm pretty sure that is the issue based upon symptoms. I will be taking it to the dealership today and will post updates. I had to replace the DMF on my Cummins Diesel Dodge pick-up myself, but this should be warranty. Not happy about DMFs in general, and if that turns out to be confirmed (I'm about certain that is it already), I'll be looking for a SMF option the moment this thing is out of warranty.


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## RichLo1 (May 31, 2018)

I dont know why they had to re-invent the wheel (or flywheel that is, lol) just run a solid steel one like whats been done and proven for the past 100 years.


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## MRO1791 (Sep 2, 2016)

RichLo1 said:


> I dont know why they had to re-invent the wheel (or flywheel that is, lol) just run a solid steel one like whats been done and proven for the past 100 years.


I think it has to do with several factors, and you can bet that if they are putting in a MORE expensive part then there has to be a reason. I think the biggest is the demand from the consumer for smooth, low vibration, and low noise, but there has been improvments in low RPM power and torque, and to improve MPG they final drive RPM is lower in modern cars than it used to be, which is where the vibration is most noticable. I can tell you it is very easy to feel and hear the difference in my truck now that the DMF is gone, and a SMF flywheel and clutch system in in place, but I don't mind the noise and vibration, and more frequent downshifts.. it's a truck, I expect it to drive like one, but people like me are in ever decreasing numbers out there. I have started the search for the SMF conversion for the Diesel Cruze, as of now it does not appear there is a supplier that makes one, hopefully there will be sometime soon. In the meantime, NEVER, EVER, EVER let up on the clutch pedal too fast after push to start, I'm about certain that can cause a backwards start, and vibrational chaos sufficent to kill the DMF is mere seconds. 

Flywheels, Solid, Dual Mass and Flywheel Conversion Kits


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## RichLo1 (May 31, 2018)

Yea, I hope that there is a solid conversion out there once mine ends up blowing apart or the clutch needs to be replaced. ****, even an aluminum one with a steel insert is more reliable than these it seems.


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## MRO1791 (Sep 2, 2016)

Dealer finally got it apart, and as I told them, the flywheel is the issue in my case. They have parts on order. One short "reverse" start cycle, that I think was caused by a too early release of the clutch caused destruction of the flywheel in a matter of seconds. DO NOT let up on the clutch after push to start until it is certain the start sequence is complete, it appears that the engineers did not build into the programming any safety to prevent this mode of failure. There are no current single mass flywheel conversion kits on the aftermarket for this car, at this time.


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## 91794 (Mar 25, 2015)

Mr. O, thanks for the followup. That really is an extraordinary failure mode, as if the clutch pop caused the barely-turning-engine to "bounce" off the flywheel and reverse direction. 
Theoretically can these cars be "push started" if the battery is too weak to restart the car while stranded on Donner Pass pointing downhill? 
I'm reminded now to put stickshift cars in neutral before starting them. And to let any car idle for at least a few seconds after startup before engaging touching shifter or clutch pedal, even if being chased by Freddy Krueger.


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## MRO1791 (Sep 2, 2016)

Have the car back, it appears the dealership did good work. There were several parts in the clutch that had updated part numbers... Meaning that GM changed them.. likely due to early failures. Once I get the picture of the invoice I'll post it. 









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## dundonrl (Jul 11, 2017)

The other day I jumped in the Cruze (2017 Sedan, diesel with 6 speed manual) after doing some shopping, sat down, pushed the clutch in and started the engine. I don't know if I let the clutch out too soon but it was noisy etc till I was able to shut off the engine using the push button on the dash. It started up correctly after that but the clutch pedal wasn't smooth and you could hear a noise coming from the engine bay that wasn't there before. It went to the dealer and they couldn't find anything wrong. I wonder if it's the DMF that's acting up. 

Oh, I have a 2012 Ram that I just replaced the OEM DMF with a South Bend dual disc organic clutch, and while you can hear gear rollover it like it a lot more than the factory DMF since I can now pull +30K lbs with it, and it doesn't slip at all like the OEM clutch did (it still had half the life left on it when it was removed, just slipped under 1/2 throttle or more)


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## MRO1791 (Sep 2, 2016)

dundonrl said:


> The other day I jumped in the Cruze (2017 Sedan, diesel with 6 speed manual) after doing some shopping, sat down, pushed the clutch in and started the engine. I don't know if I let the clutch out too soon but it was noisy etc till I was able to shut off the engine using the push button on the dash. It started up correctly after that but the clutch pedal wasn't smooth and you could hear a noise coming from the engine bay that wasn't there before. It went to the dealer and they couldn't find anything wrong. I wonder if it's the DMF that's acting up.
> 
> Oh, I have a 2012 Ram that I just replaced the OEM DMF with a South Bend dual disc organic clutch, and while you can hear gear rollover it like it a lot more than the factory DMF since I can now pull +30K lbs with it, and it doesn't slip at all like the OEM clutch did (it still had half the life left on it when it was removed, just slipped under 1/2 throttle or more)


It's almost certainly the DMF that has failed. It's impossible to confirm without removing the transmission. I'm sure the dealership won't just do that as a quick diagnosis. 

If not fixed, the DMF can further degrade and even come apart. I'd recommend you insist they do a proper diagnosis, especially if you are almost out of warranty. 

The clutch is not likely under warranty, but the DMF should be under the 3/36K. 

One of the other forum members who had a DMF failure is working with an aftemarket single mass conversion for the manual Cruze.

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## rcruze (Mar 22, 2018)

Well I am glad that you did not have a second DMF failure...and I am glad to see new part numbers for the parts, hopefully a redesign helps solve the issue.


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