Broken Crankshaft Count?

Please pick the one that you had break


  • Total voters
    185

Bigdirtylbz07

New member
Feb 3, 2011
179
0
0
Northeast indiana
Over the years there have been a few pics of broken ones at #4. Unfortunately, we aren't that special.......:dr:


Lol I wouldn't say I feel special at all especially having this truck down for almost 3 years! I just haven't heard anyone discuss about the crank failure at that spot just at the front.


Sent from a truck somewhere in the US
 

DBUSHLB7

Team DMAX
Mar 9, 2012
2,789
0
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Albuquerque, NM
This stuff has got me stressin too. Mostly because I can't afford to tear mine down and do over. Steve's breaking is what started my fears and now this thread really amped up the paranoia:mad:
 

DMAXchris

It’s only temporary!
Apr 28, 2009
2,273
2
38
44
Natrona Heights PA
In my experience the LBZ/LMM are more common but that might have something to do with the 6 speed transmission. A 5 speed truck cruising at 70-75 mph is past the 1650-1850 rpm range Mark mentioned. The 6 speed hangs out there all the time. But I'm still nervous my LB7's crank days are numbered:(

Glad my TCM tune doesnt let the trans shift into 6th until 77 mph!
 

Bigdirtylbz07

New member
Feb 3, 2011
179
0
0
Northeast indiana
Better hope it doesn't bust damian there's a dmax coming to your town in a year and a half :) sure would hate to be a loaner lol, just buy a AF cam and throw it in for preventive measures


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JoshH

Daggum farm truck
Staff member
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Feb 14, 2007
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Lol I wouldn't say I feel special at all especially having this truck down for almost 3 years! I just haven't heard anyone discuss about the crank failure at that spot just at the front.


Sent from a truck somewhere in the US

Is this how yours broke?

attachment.php
 

Bigdirtylbz07

New member
Feb 3, 2011
179
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Northeast indiana
Yea I guess it was pretty close to your picture still unfortunate, I think the convertor and copilot had something to do with it, 4th would lock up so hard my turbo would bark,(the ex beating the hell out of it either to 4800 rpms and 121 mph didn't help either lol)


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JoshH

Daggum farm truck
Staff member
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Feb 14, 2007
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That was on an LMM with an Edge Evolution on a low setting and a DPF delete. I have no idea what it was doing when it broke, but I doubt it was anything serious. It was a company truck, so who knows how it was driven.
 

Bigdirtylbz07

New member
Feb 3, 2011
179
0
0
Northeast indiana
Guess it's a good thing I went to the lb7 crank, I got a good deal on one that a guy bought straight from the dealer and had it cryo treated(doubt it adds for anything but it's been done) and I got it for 1200 so I figured I couldn't go wrong with it


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Fingers

Village Idiot
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Apr 1, 2008
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White Oak, PA
On these back of the engine breaks, did anyone magnaflux or die penetrate test the other throws? That is, was it cracking elsewhere too?
 

PACougar

Active member
Jun 27, 2012
2,105
1
36
41
El Dorado Hills, Ca
This crap is way I never take my truck anywhere far... Or out of town. Take the trusty RAM

I think you're really playing into the fears, it's not like 50 percent of peoples cranks are breaking. Of course we hear about the ones that break, how many Duramax's have been produced and how many have actually broken cranks?
 

DMAX497

New member
Sep 27, 2012
398
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Utah
I think you're really playing into the fears, it's not like 50 percent of peoples cranks are breaking. Of course we hear about the ones that break, how many Duramax's have been produced and how many have actually broken cranks?

This is true.

However, the reason I said that is I still stock bottom end and if a piston cracks out if town. That would suck. Especially after watching my old LBZ crack one in front of me.

I daily my truck to work because it's fun to drive.

Anyways back on track.
 
Last edited:

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,691
5,848
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Phoenix Az
ive got well over 100k highway miles with the motor running at 1800rpm. no issues thus far but that RPM no longer happens at cruise since the gears went in in January. Brian and i atleast have a spare crank ready :D