LML total delete

2004LB7

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I totally deleted my LML from my life entirely and replaced it with an LMM for reliability reasons...
Are LMM's really that much more reliable than the LML?

The LMM doesn't have the DEF, SCR and related sensors. But still has the DPF and CAT. Uses post injection to heat the DPF for regeneration which can wash down the cylinders and hurts power while in regen. LML uses a 9th injector to provide the heat needed for regen so seamless while driving. LML had the CP4 which has been known to fail at higher rates then the CP3 that is in the LMM.

I guess one could argue, especially with the DEF setup and CP4, that the LMM is more reliable. But I'd argue that we pretty much have all those things figured out and know how to deal with them now. With that being said. I have an LMM
 

pl_silverado

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Jan 29, 2012
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Are LMM's really that much more reliable than the LML?

The LMM doesn't have the DEF, SCR and related sensors. But still has the DPF and CAT. Uses post injection to heat the DPF for regeneration which can wash down the cylinders and hurts power while in regen. LML uses a 9th injector to provide the heat needed for regen so seamless while driving. LML had the CP4 which has been known to fail at higher rates then the CP3 that is in the LMM.

I guess one could argue, especially with the DEF setup and CP4, that the LMM is more reliable. But I'd argue that we pretty much have all those things figured out and know how to deal with them now. With that being said. I have an LMM

In my opinion/experience, yes they are more reliable. Unfortunately I'm well ver$ed in all of the generations of duramax motors and their equipment with all the repairs and rebuilds over the years.

All 3 of my lml's were crap. One was plagued with emissions issues, solved that and then promptly lifted the heads. Then the turbo went. Second one no one could get the tunes right. Literally no one, and obviously every tune is locked down so you can't try to fiddle with it yourself to figure it out. This resulted in Reduced Engine Power Mode while towing on a regular basis.

I wouldn't buy another one. So far that's the only generation that's actually left me stranded. I'd like my LBZ back but the body style is getting a little long in the tooth for me, and I've gotten used to an 07-13 body, which I personally think its more comfortable. Having had 15 different duramax trucks over the years from lb7 to l5p. I'll keep the LMM as long as I can keep it running. My only complaint with the 01-10 generation was the soft rear springs and excessive sagging with a load, but that's easily remedied with a pack of 7/1 springs off rockauto making them perform like they should have from the factory. That and one day I'll throw another fixed vane on it and get rid of the vgt crap.

LBZ's are still hot commodities right, as is evident with the asking prices on the used market. Well it doesn't take much to make the LMM an LBZ wrapped in a new body. I'll leave it at that.
 

2004LB7

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In my opinion/experience, yes they are more reliable. Unfortunately I'm well ver$ed in all of the generations of duramax motors and their equipment with all the repairs and rebuilds over the years.

All 3 of my lml's were crap. One was plagued with emissions issues, solved that and then promptly lifted the heads. Then the turbo went. Second one no one could get the tunes right. Literally no one, and obviously every tune is locked down so you can't try to fiddle with it yourself to figure it out. This resulted in Reduced Engine Power Mode while towing on a regular basis.

I wouldn't buy another one. So far that's the only generation that's actually left me stranded. I'd like my LBZ back but the body style is getting a little long in the tooth for me, and I've gotten used to an 07-13 body, which I personally think its more comfortable. Having had 15 different duramax trucks over the years from lb7 to l5p. I'll keep the LMM as long as I can keep it running. My only complaint with the 01-10 generation was the soft rear springs and excessive sagging with a load, but that's easily remedied with a pack of 7/1 springs off rockauto making them perform like they should have from the factory. That and one day I'll throw another fixed vane on it and get rid of the vgt crap.

LBZ's are still hot commodities right, as is evident with the asking prices on the used market. Well it doesn't take much to make the LMM an LBZ wrapped in a new body. I'll leave it at that.
Most of the issues you described are not the fault of the truck but from modifications that weren't done right. The LML can be an awesome engine. Even more so with the CP3 conversation and a proper tune
 

pl_silverado

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Jan 29, 2012
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Most of the issues you described are not the fault of the truck but from modifications that weren't done right. The LML can be an awesome engine. Even more so with the CP3 conversation and a proper tune

Point is they shouldn't need to be deleted or need a cp3 conversion to be made reliable. Older stuff was not designed with emissions as a priority and will undoubtedly be more reliable and last longer with relatively minimal maintenance compared to lml trucks.
 

2004LB7

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Point is they shouldn't need to be deleted or need a cp3 conversion to be made reliable. Older stuff was not designed with emissions as a priority and will undoubtedly be more reliable and last longer with relatively minimal maintenance compared to lml trucks.
Barking up the wrong tree here. We all know that. Point is, GM isn't the one forcing this down on us. It's the unelected 3 letter agency. If you want change then you need to raise hell with the elected representatives that put these people in power and make the laws that these people enforce.
 

Stroked06Goat

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Mar 30, 2023
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Hey i was in DC last weekend and walked by their office. I flipped em off. Felt good. o_O

+1 here for the LMM. I sourced exactly an LMM for said reasons. These DPF's work fairly good i had no trouble with mine at 200k. I would have gone with the LBZ but....newer body style and interior reasons made me want to jump up. Back in 19 the L5P's were pretty stout price tag comparatively.

Funny how some rando stirs up a 7 year old thread :)