Flywheel broke 2012 V8 Silverado, with pics

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Had an interesting failure on a truck at work, 2012 Silverado 4.8L V8 / 4L60E auto with about 180K miles on it.

It has been making a knocking noise for a while that was suspected to be the flywheel...found out it for sure it was...
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The driver said there wasn't any real noise when it happened, it just stopped pulling as he was going down the interstate. He pulled over and it was still running, but the AC cut off, so he turned it off and tried to restart, and nothing. It took out the starter pinion too.

Reman starter, new flywheel, and a trans mount and it's back on the road. Amazingly no other damage. The guy who usually drives the truck is not abusive, but some of the previous operators probably were.
 
Well that's not ideal. O and before anyone says anything, Ford calls it a flywheel no matter if the vehicle is an automatic or manual transmission.
 
Good time to do the rear main seal and front trans seal also, that would be high on my list while I was in there with 180K on it.
 
??? Trying to think what could cause a failure like that. The only time it serves a purpose is when the starter kicks in. From what I can see, the teeth seem OK.

Thinking one of three things:

1) Defective part (weak metal or slightly warped) that gradually bent over time under starter load.
2) Starter somehow not installed properly and bendix gear not engaging squarely.
3) Bolts loosened-up over time.

Any other ideas?
 
Originally Posted by RayCJ

??? Trying to think what could cause a failure like that. The only time it serves a purpose is when the starter kicks in. From what I can see, the teeth seem OK.

Thinking one of three things:

1) Defective part (weak metal or slightly warped) that gradually bent over time under starter load.
2) Starter somehow not installed properly and bendix gear not engaging squarely.
3) Bolts loosened-up over time.

Any other ideas?



Well, it does transfer all the power from the engine to the torque converter, so there are constant stresses there. I'm going with there was some point on there that was jagged from manufacture and it formed a place for stress to concentrate and it just spread over time, or a weakness in the metal.
 
Originally Posted by Trav
Good time to do the rear main seal and front trans seal also, that would be high on my list while I was in there with 180K on it.


Whenever I sell one or a clutch I suggest it but very few people want to do it. I guess they think I am a stealer type employee, their loss.
 
Originally Posted by bdcardinal
Well that's not ideal. O and before anyone says anything, Ford calls it a flywheel no matter if the vehicle is an automatic or manual transmission.


Haha, yeah I guess flexplate is the more technical term for an AT, but flywheel is the term I have usually heard and used. I think the part description GM used was "plate, a/t flex," but then elsewhere they refer to it as a flywheel.

Trav's advice would be the best way to go about it, but it wasn't a good time to try to get anything extra approved, so no dice.

As for the cause, no idea, but it has been a long time coming. It has been making noise for over a year, and a couple weeks ago the driver mentioned it sounded like it was getting worse.
 
Last edited:
Originally Posted by atikovi
Originally Posted by 01rangerxl
Flywheel broke 2012 V8 Silverado, with pics


That's a flexplate.


Ford for one calls them all flywheels no matter the transmission type.
 
Originally Posted by bdcardinal
Originally Posted by atikovi
Originally Posted by 01rangerxl
Flywheel broke 2012 V8 Silverado, with pics


That's a flexplate.


Ford for one calls them all flywheels no matter the transmission type.


OP's car is a Chevy.
 
Originally Posted by atikovi


OP's car is a Chevy.


If you want to nit pick it's a Chevrolet light truck, and it's not mine.
 
Originally Posted by ctechbob
Originally Posted by RayCJ

??? Trying to think what could cause a failure like that. The only time it serves a purpose is when the starter kicks in. From what I can see, the teeth seem OK.

Thinking one of three things:

1) Defective part (weak metal or slightly warped) that gradually bent over time under starter load.
2) Starter somehow not installed properly and bendix gear not engaging squarely.
3) Bolts loosened-up over time.

Any other ideas?



Well, it does transfer all the power from the engine to the torque converter, so there are constant stresses there. I'm going with there was some point on there that was jagged from manufacture and it formed a place for stress to concentrate and it just spread over time, or a weakness in the metal.


Ahhh, OK... I'm thinking this was a simple ring-gear situation and the torque converter was held more directly by other means. Now I see... this flexplate is an intermediary attachment of the converter... Yeah, it's got some stresses going thru it for sure.
 
Surprising to see just 3 bolts is all that connects the engine to the transmission on a truck. [censored], I was surprised to see that when I replaced the transmission in a Spark.
 
Originally Posted by atikovi
Not picking nits, but if you go online or into a parts store and order a flywheel for a Chevrolet light truck, that's not what you're going to get.


Only if you're the type that walks into a parts store and says "gimme a flywheel for a V8 Chevy", most people buying this kind of part can figure it out without fretting over the most technical name to use.

The mechanic said "the flywheel is messed up," I ordered the part, and I did not get one for an MT truck.

I suppose every time someone uses the term driveshaft, I should tell them it is actually a propeller shaft? Come on now.
 
Originally Posted by bdcardinal
Originally Posted by Trav
Good time to do the rear main seal and front trans seal also, that would be high on my list while I was in there with 180K on it.


Whenever I sell one or a clutch I suggest it but very few people want to do it. I guess they think I am a stealer type employee, their loss.

It makes no sense at all not to do those seals when the transmission is out with that amount of miles on the vehicle.
 
Originally Posted by 01rangerxl
Originally Posted by atikovi
Not picking nits, but if you go online or into a parts store and order a flywheel for a Chevrolet light truck, that's not what you're going to get.


Only if you're the type that walks into a parts store and says "gimme a flywheel for a V8 Chevy", most people buying this kind of part can figure it out without fretting over the most technical name to use.

The mechanic said "the flywheel is messed up," I ordered the part, and I did not get one for an MT truck.

I suppose every time someone uses the term driveshaft, I should tell them it is actually a propeller shaft? Come on now.



lol.gif



Right on....
 
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