The LMM Duramax - Reliability & 5 Common Problems

[@b00nd0cksa1nt1979]

Im a hotshot driver. Owner/ operator, and i run an 08 lmm. I agree with all you said. Just hitting 330k miles. And my lower trans cooler line started leaking on me today. So i replaced it. Will be upgrading them when i get home. And i agree with deleting it will see the most reliability as mine is. Just keep up on your maintenance and it will give you years of good reliability. So with that being said, great video and i just subscribed.

[@8020Media]

Boon - We completely agree. Thanks for sharing your experience and feedback!

[@alextorkelson]

Have you had to replace injectors at all? Blowing white smoke on mine at WOT time to time.

[@8020Media]

Alex - Based off of the white smoke, it leads us to these: fuel injectors, coolant leaking, or incomplete combustion. Are you getting any CEL's? Keep us updated on this.

[@paullucas3]

Thanks for sharing, I’m trying to find a reliable older truck.

[@jflowers090]

So if you delete it and keep it relatively stock it's very reliable.... I love it.

[@8020Media]

J - 🎯

[@2ndAmendmentGlock]

Mine is plagued with reduced engine power error as well as P101. Another common issue is kinked fuel lines. Also had the head gasket blow. I really want to love this truck, it is so much more comfortable than my ram 3500, I have gone 2k miles almost nonstop in that cab and enjoyed every moment of it, except for the "reduced engine power" moments.

[@8020Media]

2nd - Sorry to hear about this, but thank you for taking the time to share your experience.

[@cameronchiles]

What causes ur reduced engine power

[@2ndAmendmentGlock]

@@8020Media Discovered the solution! Bad fuel pressure regulator! Now she's running good! Thank the Lord!

[@8020Media]

2 - Nice! Thanks for coming back and updating. This will certainly be helpful for future viewers.

[@happygnome4620]

Very excited to become a new LMM owner. The one im looking at has only 200xxxkm! I could see myself giving it a much needed delete, but it is a nightmare being a semi-broke high schooler!

[@8020Media]

H - They can certainly last much longer than 200k km! Just a matter of the maintenance that he was performing. Keep us updated!

[@cadeneby5186]

U get the truck yet ?

[@happygnome4620]

Just a couple grand short as of now...should only be a week or two of work more!@@cadeneby5186

[@orvillestory6958]

My 2007 DuraMax is still my daily driver at 360,000 plus miles. However, I did straight pipe it at 120000 miles.

[@8020Media]

Orville - Very impressive! What else do you have done to it?

[@brianbevans6804]

​@8020Media my 08 ltz alc is at 270k all original aside from a few bolt ons, full delete, 4"dp, 5" exhaust axle dump, cold ram air induction- ram air hood with ducting that seals into the intake, efi live 5 tunes on dsp switch, I generally run tune 3 or 4 around 100 or 150hp tunes, tune 4 burns through fuel filter extremely fast tho, have had 0 issues ever, I'm 2nd owner. Weed to change 2 glow plugs that she keeping my remote start from working, need to do my thermostats soon as 1 is stuck open making the truck run cooler & not blow very hot heat, universal joints in the rear are going bad, & need to do some suspension & steering parts soon- shocks, wheel bearings, idler/pitman arms, tie rods. All things listed have just stated going bad in the last 3k miles & all are completely original, have towed 8-10k lbs on a few 800-1000 mile trips in the last year without issue, truck is an American Luxury Coach dealer lifted new on 36x12.50x22s. So it's surprising that all parts are original turning those big wheels & tires since 1, I always kept everything greased & fluids changed but it's all just getting to to point of replacement. Tranny shifts quick & smooth, rear locker works perfect even after a few burnouts & 4x4 launches, only a few tho. Still deciding between oem parts or upgraded aftermarket. Truck made 590whp and just over 1200 ft lbs on tune 4, tune 5 will put the trans into limp mode if you try to beat on it. I average 18mpg. On 35ats & 22x12s , every button & light works perfectly, only has a quarter sized rust spot starting on the driver rocker I'm about to fix before it gets worse, & the driver seat has a small 3" tear I need to replace the leather cover. Been the most reliable vehicle I've ever owned next to an old 91 celica I got 400k out of & sold running perfect to my cousin who drove it 2yrs and then sold to his dad who drove it 4yrs an sold it still running, couldn't kill that car and we all beat on it regularly, that would be my apocalypse mobile if thr need ever arose, lol. My fiancés Camry xse v6 is the next most reliable I've ever purchased, I bought it new in 2016 and it's all original with 230k miles 0 issues or parts replaced aside from fluids, filters, tires, wipers, & brakes. We both want newer lower mileage vehicles now that we've had both of ours for many years but there's nothing newer that either of us trust to be as reliable. She's thinking either an 18-21 camry or lexus premium model & I'm thinking an 11-14 lml sierra denali with cp3 swap, full delete, & bolt ons considered an l5p but really on the fence.

[@charlesswearengin2404]

I to own a 08 LMM and just subscribed, wanting to do a egr delete, but finding a true exhaust is next to impossible. I've HSP everything but the cold side up pipe and exhaust, the motor is still factory hold off on up grades until needed.

[@8020Media]

Charles - Yup, since these are a little older it's quite difficult to get hands on upgrades nowadays.

[@ItsFocial]

Just got a 08 LMM had a LB7 before hand the only issue ive noticed is electrical mind you my LMM is fully deleted and tuned so i guess i don't see a lot of these issues. I noticed alot of complaints on the LMM is emissions but me being from a state that has no emissions when i deleted it ive had zero issues with this truck other than electrical AKA the gas gauge and fuses? Dont know if anyone have seen this but LMK!!

[@8020Media]

I - You went the right route! Thanks for sharing.

[@AlexJonesWasRight1776]

I HAVE AN 09 GMC 2500 CREW LOADED EVERY OPTION BOUGHT AS REPO AT MY CREDIT UNION IN 2012 for $ 41k first thing i did was delete all emission systems control and install a tuner made by H& S called the Mini Max this was needed because it allows for normal operation without dPF SYSTEM AND egr SYSTEM. i ALWAYS LEAVE THE TUNE ON sTREET mODE EVEN WHEN TOWING. i STRAIGHT PIPED IT WITH 5.5 TURBO BACK. Installed cold air intake K&N I now have 178K miles on it street hot rod driving and toy hauler towing never touched anything under the hood except for regular maintenance, No leaks no issues. last year i had the Allison performance built for $15,000 worth every penny now the truck drives like it should have from the factory, VERY AGGRESIVE SHIFTING always in the perfect gear for turbo spool efficiency I also installed a FASS fuel lift pump made huge difference in performance as well I cant say enough positive things regarding the deleting of Emission controls. and proof is in what i did the delete with 14K miles on it. I am now averaging 21 mpg combined city and highway and get as high as 27mpg on long freeway drives with no load or towing something. Iv replaced shocks 3 times with Bilstein coil overs did the Ujoints at 150K miles. serviced every fluid in truck 2 times more frequent then GM calls for and used all GM fluids. I replaced the front wheel hubs at 130k miles with factory GM units and no issues that you hear about from aftermarket ones the factory hubs run $650 a pierce but worth it in my opinion all my buddies keep buying cheap wheel hubs and they go out every 25 miles it seams. did the brakes once at 100k and replaced rotors with slotted and drilled rotor's and bought $500 ceramic race brake pads it doubled my stopping power. All electronics work in the truck and for a loaded ltz model thats saying something. I did delete the airbag system, OnStar system and permanently bypassed the traction control and Stabil track system. bypassed drl headlight system and modded so fog lights low beams AND HIGHH BEAMS all work together at once and upgraded to very illegal bright LED headlights both high and low its like having a rally truck type of lighting now. I did install a leveling kit when i first got the truck and run 1" longer than stock front shocks. tie rods and pitman arm at 100k miles upgraded to aftermarket performance units. rep[laced all turbo hot and cold side turbo rubber boots with PPE brand. also bypassed the annoying park assist back system. THats about it Man I love my O9 gmc DURAMAX I GET NODS ALL THE TIME FROM TRUCFK GUYS. I would not trade it for a new one no way. THe cd player LOL cd player yes.. was acting up and would read my Metallic Black Album Remastered CD so i punched the radio a few times and it works great again. Oh iv also always ran a fuel additive at every fill up since I got the truck. I think that made a big difference in injector life as well.

[@8020Media]

A - Thanks for taking the time to share your in depth experience! Sounds like you've built a mean LMM!

[@Moto290]

Nice video

[@8020Media]

Moto - Thanks for the feedback! Hope it helped.

[@cooperredd4158]

What upgraded trans cooler lines would you recommend?

[@8020Media]

Cooper - Our choice would be Alligator Performance, not super expensive. However, it's an annoying DIY, but there are plenty of guides out there.

[@davelosonczy1537]

Ty😊

[@8020Media]

Dave - Absolutely! Hope it helped.

[@bluelightingwolf85]

LML Duramax engine deleted with procharger and twin turbo and muffler, more horsepower, LBZ upgrade version 2.0 LML Duramax engine, L5P Duramax engine deleted with muffler delete sounds like 6.0 Power stroke .

[@8020Media]

B - Sick build! Thanks for sharing. How many miles?

[@charlesdonaldson962]

I don't think there's any way to know when it's in regen... Unless it's the one that initiated after it tells you that it must be done.

[@8020Media]

You're right, there isn't an easy way to know - the easiest way is to keep an eye on the mpg average as it will drop when it goes into regen, but if you don't reset this frequently then it's hard to know. You can also tell by idle speed and sound, oil life monitoring % drops a bit too, etc. But it is hard to know unless you pay attention and watch out for it frequently.

[@brianbevans6804]

Lmm is the best duramax ever made, better heads & injectors than the lbz, the dpf & egr arent an issue if the truck is used for its designed purpose, its only the people who daily drive them & dont know sht about diesels that have isseus. Driving short distances & shutting them off, never towing and working the engine getting everything hot to keep it clean. I had 0 issues with my emissions or trans lines for 100k & then I decided to delete & tune still 0 issues almost 270k. Young guys 18-early 30s who drive diesels to be cool without ever needing to tow heavy are the 1s who have issues. They drive just to their warehouse or oilfield job in square toed boots never towing anything heavy and shut the truck off never getting it hot enough and rarely regen are the dudes with issues, those guys should buy a gasser.

[@8020Media]

B - Thanks for taking the time to share your experience. We think they're also great.

[@brianbevans6804]

@8020Media do you have experience with the l5p? If so how much better than an lmm or lml is it regarding comfort- seat comfort wise, seating position, ride quality, noise; reliability, handling, driver view, throttle & transmission response, power & fuel mileage given all 3 have have equal mods- downpipe, exhaust, intake, tune; is the infotainment a preferred necessary upgrade? I'm considering selling my black lmm ltz alc & upgrading to either a 11-14 leveled black on black sierra denali lml with chrome grill & trim, with either 20" oem chrome 2017 wide 6spoke silverado ltz wheels or 20" oem chrome 2017 sierra denali wheels, or a leveled l5p 17-19 black on black sierra denali or 17-19 silverado ltz, but can't decide. I really like the look of a black 11-14 lml denali with the newer 2017 denali or ltz chrome wheels, I don't like the lml silverado, but I'm unsure between the 17-19 l5p sierra denali or silverado ltz, those are the 3 trucks I'm debating between, just not sure if the l5p is worth the cost over the lml. My lmm does everything I want easily so better towing isn't a concern, I mostly tow raceways & equipment under 10k so the occasional 12-15k lbs is irrelevant. Just want a change to something a little more classy looking & not lifted like my lmm with a 6". I like the denali lml & l5p because they're clean & classy looking, I think the ltz is a little aggressive looking like something a younger person would drive which is how I feel about my lmm, black, 6" lift, black 22x12 wheels on 35s, black housing headlight, tinted windows, & an aftermarket RK Sport ram air induction hood, it looks mean & I wanna move to something classier, cleaner, & more oem plus, just leveled with a little bigger semi aggressive all terrains on the own wheels.

[@8020Media]

B - It would be best to take one for a test drive. I feel like this would potentially help answer your questions. The L5P's, if deleted, can be great. We have a video over the L5P that may help here: kzbin.info/www/bejne/iWLGnWCGhJajgdE

[@dooner777]

Do you have any feed back about the cranks not having keyways ?

[@CallMeTheRealE]

All I’m hearing is if you tune and delete it then you have 2 problems pistons and transmission lines leaking a bit

[@8020Media]

E - Pretty much. But we can't advise deleting.

[@hb-gv1te]

Looking at a used LMM, 350K miles for $11,000 seems steep. Has been deleted. Thoughts?

[@8020Media]

HB - It all depends on how well it has been maintained. Assuming that it has been maintained well since it is at 350k, but that's still a lot of miles. It being deleted certainly helps with reliability and longevity.

[@burdendmist6543]

Sounds like the truck i just bought a month ago

[@bradyandreas]

well mines daily driven and pushing 750 to the wheel

[@8020Media]

Nice Brady! What are your specs?

[@toiletpaper5770]

Mines pushing 751

[@isaactorkelson5225]

I’m looking at a 08 that’s been deleted and tuned with efi. It has 180 on the clock should I shy away or or not be worried

[@8020Media]

I - Probably a decent buy, but it all depends on how well it's been maintained. Also, you shouldn't solely use our word for making a purchasing decision. The more research, the better.

[@christopherlawson8467]

So cool😮

[@8020Media]

C - Thanks for the feedback!

[@aaronhobart6223]

Looking at buying one 2008 llm 140k looks like 2 owners and really good service records 17400 for it idk what is a good price seems pretty clean just a little rust on the bed side above the wheel

[@8020Media]

Aaron - So long as it's got good maintenance records, then you should be good!

[@ArmyProperty]

Oddball question, since the LMM has a VGT turbo, can you tune it for exhaust brake functionality? We've got an LML and it's got 390k miles, running strong but the DEF/SCR system has been giving us nonstop trouble. Plus we know the CP4 is a ticking time bomb. So we're thinking about "downgrading" to an LMM, but just wondering if you can get the turbo to slow the truck down. For all its problems, the LML has a very very effective exhaust brake which will hold an 18,000lb trailer going down steep, steep hills / mountains. So we'd rather not have to live without it. (And naturally the LML makes about 100 lb-ft more torque, but we can live without that, if it means getting rid of the CP4 and DEF/SCR system.) Also.... is the transmission basically identical between both trucks? Thanks in advance.

[@Collin2012]

390k on a stock cp4? Holy moly god must love you

[@ArmyProperty]

@@Collin2012 hahahaha yeah we’re pretty lucky so far! I guess everybody is…. until they aren’t!

[@carsonc.2796]

My LMM has a tuned in exhaust brake and it works very well.

[@brianbevans6804]

Yes you can tune for exhaust brake, however deleting & doing an open flow exhaust will reduce its effectiveness. My 08 is fully deleted & tuned with 4"dp, 5" exhaust, ram air induction hood & intake, efi live 5 tunes on dsp switch, and the simple trans go jr, I've only towed 12k with mine but had 0 issues and it towed it easily. Last year I was towing 7k lbs on tune 3 & a newer stock height cummins towing a like 500cc 4wheeler on a little like 5x7 trailer tried to race me uphill on the hiway. & I put like 8 length on him by the top on my lower tune & I'm lifted on 35s my buddy bought a 21 cummins on 35s tuned with exhaust & from a dig or roll I would embarrass him, his truck would barely spin the 35s without powerbreaking, if I punch my lmm below about 40mph it just melts my 35s, I previously had an 03 5.9, 00 7.3, & 05 6.0 & none of them come close to my lmm in power or reliability.

[@1Clean350z]

Hey so I’m new to trucks I bought a lmm duramax and it was driving fine for couple days then recently it flashed “engine power reduced “ then went away and drove fine didn’t think much about it but drove it later and it did it again flashed and went away. It does it every other drive any ideas of what can be thank you!

[@8020Media]

Clean - Welcome to the Duramax family. We love Duramax's. Here's an article on our Tuning Pro site that may not be for a Duramax, but it is still relevant to the underlying issue. tuningpro.co/reduced-engine-power-warning/

[@LBZDIRTYYMAX]

Is it deleted or does it still have emissions

[@jkreviea]

Either the tune, or injectors.

[@brianw564]

Run the factory air filter the other ones dust gets into them. Yes they are more money but no issue. I ran a Napa filter here in Canada and during a snow storm mine did the same. Went to the dealership and replace it with the ax delco factory one and no more flashing light. Hope this helps and enjoy your lmm. Mine is 2010 and at 248000 km. Yes deleted with efi live stock tune and runs perfect and mbrp exhaust from the turbo back.

[@jaydengarcia-i1f]

honestly depends on if the truck still has a dpf or not. i have an 09 lmm and i kept getting engine power reduced codes and was running like crap. at first investigation i thought it was the maf sensor going bad after reading codes. it ended up being the dpf was clogged and the motor couldn't breathe. if it gets worse as you put more miles on the truck i would take a look at the dpf.

[@coryt-notctk6822]

What do you need to “bullet proof” a LMM to push abt 800hp without cracking pistons

[@8020Media]

Cory - First off, pushing an LMM to these power levels won't be cheap. It's going to be a full build including upgraded turbo, fuel system, internals, transmission (the Allison 1000 can't hold this much hp), custom tuning, and many more.. what is your budget?

[@coryt-notctk6822]

@@8020Media just long term like 10-20k ish already got a FASS 165 and make abt 550 roughly 460 whp

[@zaknefain100]

@@coryt-notctk6822 Pull the engine, do pistons, rings, wrist-pins at a minimum. Then the needed trans mods to support it. Of course.. turbo and fuel system if you're not already there and tuning, as mentioned.

[@failorfarms88]

wouldn’t hurt to put a GOOD crank in it too, they are more known to break the crank, than cracking the pistons. From what I know anyway

[@victore.4377]

Way better than the Lbz 🤫

[@8020Media]

Victor - Everyone is held to their own opinion😉

[@Loadstamler]

Order flexible, better quality transmission lines

[@8020Media]

We completely agree.

[@SheltonArnold-k6k]

I have a 07 gmc 6.6 an it just died out on me today, i have no power to my fuse in the fuse box under the hood

[@8020Media]

S - Sorry to hear about this. How many miles did you have on it? Did you take it to a shop?

[@SheltonArnold-k6k]

@@8020Media it has 349k miles, it just happened yesterday and don't really have money for a shop at the moment

[@AlexJonesWasRight1776]

check your main wire harness plug under the hood its mounted ontop of the motor i had 3 buddies with same issue the connector has over 30 wires in it and all the prongs were dirty and corroded a good clean and repack with dielectric grease solves that issue.

[@brandonlaird-brundidge5232]

So the truck is just as reliable as the famous LBZ if not more and 99% of your problems can just be deleted.

[@8020Media]

Brandon - Correct, but a lot of people don't/can't delete all of the emissions.

[@Ponykeg53]

Jake...just what the hell to you call low millage and High millage give us a F-ing range other than that I really like your break down. is a Lmm with 292073 miles worth buy or would I just be buying someones elses neglecten wreack.

[@8020Media]

Pony - Quite aggressive start to the comment lol, but thanks for the feedback. Depends how much it's going for. We've seen many LMM's go 300k+.