Broken crank/lower end troubles

[webb06]

Got a cab chassis 6.7 in our shop this week. 12x,xxx miles on it all stock. Anyone seen broken cranks? Or what has been seen as far as lower end problems?

Also what are the differences in cab chassis engines and pickup engines besides turbo, and piping and intake manifold, and ecm calibration? If anything?


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[6.0 Tech]

I have seen rod bearing failures on trucks that were ridden hard and put away wet. Not a ton, but probably 5-10. Usually they are around the 90-150 range. Seen one at 75 though. Gavent seen a broken crank yet, but if you did have a rod failure, it could break the crank. The early 11 trucks had issues with head castings causing the exhaust valves to drop into the motor.

I believe that those are the only differences between the two engines. Other differences are in the exhaust layout. I believe its the *** and scr mixing chamber that are switched from the pick ups.

 

[ghohouston]

https://youtu.be/EnGPLN_b7_w sound like this?
Here's a video after they pulled the engine https://youtu.be/5C-sh6kvAsw

 

[webb06]

https://youtu.be/EnGPLN_b7_w sound like this?
Here's a video after they pulled the engine https://youtu.be/5C-sh6kvAsw

Almost identical to that. Not quite as loud of a thump but close.

Was that crank broken?


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[webb06]

Anyone else seen anything like this on a 6.7? I'll be pulling the cab and engine early next week to see what kind of damage is done on the bottom end.


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[ghohouston]

Almost identical to that. Not quite as loud of a thump but close.

Was that crank broken?


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I never found out for sure, but that was certainly my guess, with the amount of play at the snout of the crank

 

[webb06]

Just because everyone likes pics. I got the cab off and engine out today before lunch. First time doing this on a 6.7 too.

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[sootie]

there is a reg cab over there that needs some attention....

 

[webb06]

there is a reg cab over there that needs some attention....

I knew someone was going to say something about that poor truck


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[webb06]

After getting the upper and lower oil pan off there was nothing obvious showing up. So I pulled off the main caps individually and still nothing. All main bearings looked great.

Hooked the starter back up and spun the engine using that. There still seems to be a vibration in the engine just by using the starter.

When I spun the torque converter by hand it makes an awful racket just by spinning as fast as I can with my hand. Also the front transmission seal was leaking because when I separated that engine and trans there was a small amount of fluid that came out.

Any suggestions? Can a torque converter cause a vibration and noise not quite as bad as the video above?

When the truck first came in we removed the lower plastic oil pan and found small slivers of metal in the bottom of the pan. That's what led us to believe there was lower end problems.

Also this engine was replaced under warranty when the truck had 33k miles, now has 120k.


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[Dzchey21]

the noise in the video sounds identical to the truck that had that broke a crank in a 6.4.


Converter or flex plate would not most likely make that sound but they do make some noise when they break. Did you check thrust on that engine to make sure it didn't break between a main and a rod journal? The one I had I almost thought the engine was fine until I moved the damper but the flex plate didn't move and vice versa.

 

[webb06]

the noise in the video sounds identical to the truck that had that broke a crank in a 6.4.





Converter or flex plate would not most likely make that sound but they do make some noise when they break. Did you check thrust on that engine to make sure it didn't break between a main and a rod journal? The one I had I almost thought the engine was fine until I moved the damper but the flex plate didn't move and vice versa.

The thrust is on the back main. It is in 2 pieces but it appears to be made that way? When I pulled the rear main cap the lower half came with it and looked okay.

The plan tomorrow is to put the pans back on and dump some oil in it. Then get it started on ether and run it just a few seconds to see if it's smooth or not. Probably not the best but it ought to tell us one way or another.

The converter also had 3 of the 8 nuts loose, like halfway on the stud, so it wallowed the flex plate holes pretty good. But I wouldn't think that would cause the truck to all of a sudden develop this vibration/noise like it did.


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[JMart]

There was a guy in out local club forum that had a c&c 6.7 break the crank. The truck was still under warranty so the dealer had to put a new engine in it.

 

[6.0 Tech]

the loose nuts could definitely cause a noise/vibration. were the three tight ones across from eachother, or next to each other?

 

[webb06]

the loose nuts could definitely cause a noise/vibration. were the three tight ones across from eachother, or next to each other?

I don't think it could cause this bad of a vibration though. Seems like the 3 loose ones were all in a row


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[78f100]

I had a 6.0 brought in 2 weeks ago customer thought it was knocking, converter bolts were all loose. It had egged the holes and was making a awful noise and a bad vibration. Put in a new converter and seal was good to go.

 

[webb06]

I had a 6.0 brought in 2 weeks ago customer thought it was knocking, converter bolts were all loose. It had egged the holes and was making a awful noise and a bad vibration. Put in a new converter and seal was good to go.

We are leaning towards that as well. Should have taken diagnosis a little further before pulling cab and engine. Live and learn I suppose.


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[78f100]

I forgot new flexplate also.
I know what you mean, none of us are perfect everytime out. Life lessons you never forget.

 

[webb06]

Was able to start the engine on ether just hanging from the cherry picker, it sounded fine. Stuck it back in the frame with a new flex plate and converter and started it on ether, sounded fine. Dropped the cab and got everything hooked up good enough to start it, smooth as silk.

Lesson to be learned here for sure. A little extra diag time will save a lot in labor time.

On a side note since the customer was counting on spending coin for an engine we are now dleting the truck so they'll be happy about that.


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[sootie]

woo hoo. i figured that would do it...