Moderate LML engine rebuild... - Page 3 - Chevy and GMC Duramax Diesel Forum
11-16 LML Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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post #21 of 64 (permalink) Old 10-14-2019, 08:25 PM
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Did a number on them pushrods lol.

NIC R
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post #22 of 64 (permalink) Old 10-14-2019, 08:28 PM Thread Starter
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Originally Posted by SilverGorillaLML View Post
Did a number on them pushrods lol.
did you miss the crank?

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Stage 1 short block, ATI damper, Fass 150, CP3, upgraded trans, Up pipe, Down pipe, EZ lynk w/ 5 tunes SOTF, Magnaflow exhaust, PCV re-route, 4 inch Fabtech lift, 35in tires, HD motor mounts
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post #23 of 64 (permalink) Old 10-14-2019, 08:39 PM
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this was all on stock trans tuning?

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post #24 of 64 (permalink) Old 10-14-2019, 08:47 PM
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No I saw the crank too. Them breaking dont surprise me anymore lol if the rods are straight and pistons look good I may know someone who wants them.

NIC R
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post #25 of 64 (permalink) Old 10-15-2019, 04:26 PM
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So i saw where the OP said he was on tow tune for trans re-learn, but were you just letting this thing eat in tow tune or what? This Seems to be a little much for just being in a tow tune daily driving or towing with some sense.

2016 LML Denali 2500
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Wehrli S300 kit w/ 66mm SXE
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post #26 of 64 (permalink) Old 10-15-2019, 04:32 PM
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Cody, its probabaly Mr. Epa certifieds tuning . Cranks can snap idling, cruising down the highway, whatever.

NIC R
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"Empty Pockets" Race/Pulling truck- 2012 CCSB Cummins/Built Engine/48RE Swap/PCS2000/
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post #27 of 64 (permalink) Old 10-15-2019, 06:39 PM
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Cody, its probabaly Mr. Epa certifieds tuning . Cranks can snap idling, cruising down the highway, whatever.
Nic I appreciate you giving me nightmares for the rest of the week lmao

2016 LML Denali 2500
Mcgaughy's 2" drop shackle
Bilstein 5100
22x10 American Force Flux black w machined or Toyos on OEM wheels. Depends on the day of the week
Wehrli S300 kit w/ 66mm SXE
Wehrli CP3 conversion 10mm stroker
Profab Manifold & Up-pipes
Stock Trans For Now
Stock Sticks For Now
Air Dog 165 4G
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post #28 of 64 (permalink) Old 10-16-2019, 09:22 PM
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Do some reading on these engines and their crank issues.

NIC R
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"Empty Pockets" Race/Pulling truck- 2012 CCSB Cummins/Built Engine/48RE Swap/PCS2000/
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post #29 of 64 (permalink) Old 10-17-2019, 10:53 AM
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=====================================

I find it difficult to believe that engines with a history, down thru the years, of outstanding reliability (as is the case with our Duramax's of various series) absent abuse, meaning trying to draw significantly more power out of them then the stock "rating", will incur this kind of failure.

I have worked on and around all manner of internal combustion engines (probably a bit more than any of you in here). I have yet to see an engine do what this one did absent major abuse.

Bottom line - those of you with stock engines, and those of us who have a "tune" to take advantage of our "deletes" (but are conservative in the use of the additional power) do not have anything to worry about.


If you read enough on this forum you will see that this is in fact quite true. The duramax engine has a long history of breaking cranks at that location. This is so much of a common issue that people have created cam shafts with altered firing orders to try to remove the stress from that point on the crank. Plenty of stock trucks have broken cranks like this. There is also a track record of sheering the key out of the crank and cam as well which results in valve and piston collisions.

The Duramax engine is an exceptional engine, but it is also far from perfect. There are plenty of issues with it from the beginning of the series, most have been corrected by this point but the crank issue as far as i am aware has never been addressed by GM. It is not a huge issue, as failures are rare, but there is still a clear history of failures going back to the 01 trucks. The issues with head gaskets, injectors, cp4, are all significantly more common issues though, so that is mostly what you see / hear about.

There are also people making well over 1K HP on a stock crank with no failures, and others who break them on stock trucks. There seems to be little rhyme or reason as to why. Perhaps its a heat treating issue, maybe there's multiple production locations and one is slight harder, who knows, but this does happen.
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Last edited by J83; 10-17-2019 at 10:58 AM.
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post #30 of 64 (permalink) Old 10-17-2019, 02:08 PM
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Quote:
Originally Posted by J83 View Post
If you read enough on this forum you will see that this is in fact quite true. The duramax engine has a long history of breaking cranks at that location. This is so much of a common issue that people have created cam shafts with altered firing orders to try to remove the stress from that point on the crank. Plenty of stock trucks have broken cranks like this. There is also a track record of sheering the key out of the crank and cam as well which results in valve and piston collisions.

The Duramax engine is an exceptional engine, but it is also far from perfect. There are plenty of issues with it from the beginning of the series, most have been corrected by this point but the crank issue as far as i am aware has never been addressed by GM. It is not a huge issue, as failures are rare, but there is still a clear history of failures going back to the 01 trucks. The issues with head gaskets, injectors, cp4, are all significantly more common issues though, so that is mostly what you see / hear about.

There are also people making well over 1K HP on a stock crank with no failures, and others who break them on stock trucks. There seems to be little rhyme or reason as to why. Perhaps its a heat treating issue, maybe there's multiple production locations and one is slight harder, who knows, but this does happen.
Agreed!!
From 01 to 16 these trucks break cranks on, stock or 2000hp, babied or abused, low mileage or high. Doesnt matter. Hit or miss. Unfortunately the af cams have proven not to be the fix all eveyone thought they'd be. Plenty of guys have broken cranks with those also. Callie or SoCal billet holy water blessed narrow rod journal crank are the new fix all. We will see how they hold up. If I was building one of these engines I'd skip the 5k dollar fancy crank put a good tested one in with the cam of your choice, af or not, and hope for the best. I wouldnt say it's a super common issue but it happens more than people think.

NIC R
"Flat Back Gorilla" Daily/Tow rig- 04 GMC Sierra LB7 CC Flatbed/Tune/Exhaust
"Empty Pockets" Race/Pulling truck- 2012 CCSB Cummins/Built Engine/48RE Swap/PCS2000/
B&M Ratchet shifter/Big fuel/Big air/Lowered

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