L5p lifter failure

Hoser

Active member
Jun 19, 2016
243
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Farmington, MN
I just took my 2020 L5p in to the dealership for what sounds like this same problem. This has been the worst Duramax of all the models I have owned as far as reliability. It's already had a trans replaced at 44k miles and now sounds like it needs a motor at 49k miles. I also have a buddy who had the same issue with his 2020 and he just told me his trans is acting up. This is supposed to have been the best Duramax. For the guys that like to watch Gale Banks videos and take in the hype he spews out about them I say he is wrong. My last Duramax was deleted at 500 miles and I sold it with 250k miles. Not one issue.
How much weight are you pulling? What’s your driving style? I beat the tar out of my truck and hold it wide open with 20,000+ pound loads behind me up mountain passes. Mine has never missed a beat and the transmission has been flawless.
 

600+duramax

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Jan 18, 2007
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How much weight are you pulling? What’s your driving style? I beat the tar out of my truck and hold it wide open with 20,000+ pound loads behind me up mountain passes. Mine has never missed a beat and the transmission has been flawless.
The sad part is that this is a personal truck that doesn't tow often. I only tow my boat occasionally. You have been lucky or got a good one. I'm sure they have more trucks running than failing but I personally have never had so many issues with a Duramax. My buddy included.
 

Dozerboy

Well-known member
Jun 23, 2009
5,088
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TX of course
Still doesn't seem like a wide spread problem. So I still have faith in the Duramax. Definitely take it iver a Ram right now. Ford seems to be the only one without major mechanical issues right now. You just have to worry about fuel leaks that burn the trucks to the ground
 

Hoser

Active member
Jun 19, 2016
243
36
28
Farmington, MN
The sad part is that this is a personal truck that doesn't tow often. I only tow my boat occasionally. You have been lucky or got a good one. I'm sure they have more trucks running than failing but I personally have never had so many issues with a Duramax. My buddy included.
I see a lot more problems on these trucks when guys use them like you. These trucks aren’t grocery getters, they are made for work. I see lots of guys running them hard and towing heavy every day and some are over 200k towing every day and their trucks have been problem free.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
The sad part is that this is a personal truck that doesn't tow often. I only tow my boat occasionally. You have been lucky or got a good one. I'm sure they have more trucks running than failing but I personally have never had so many issues with a Duramax. My buddy included.

You pick your poison these days. You could have got a ford and have the cp4 explode, intercooler tube blow out, injector valve seals leak, front cover leak, etc. or you could get a dodge and have the 68 which is junk or let’s say it has the aisin, then you still have issues with front timing cover that leaks, exhaust manifolds that shrink, interior that falls apart and so on.

At the end of the day, all these new truck you basically pick your flavor and deal with the crap they are built out of. Is it upsetting to spend the kind of money they cost and have issues? Yup. Just sucks
 

2004LB7

Super Moderator
Staff member
Dec 15, 2010
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Norcal
The sad part is that this is a personal truck that doesn't tow often. I only tow my boat occasionally. You have been lucky or got a good one. I'm sure they have more trucks running than failing but I personally have never had so many issues with a Duramax. My buddy included.
Sounds like you should have got a gas truck
 

Hambone

Always learning
Jan 24, 2016
591
20
18
Florida
Back from the void... just an update to anyone who is stumbling across this.
The truck we own that i rebuilt now has 260k on the clock.
My Forman was complaining it had loose steering. Turned out to be a worn out gear box and rear end has a tremendous about of slop. New bearings and shims set to go in January.
Other than a weak intank fuel pump which ill fix when the rear end is getting addressed the truck is running great.
Out of the several l5ps we have only 2 have been cursed it seems lol
But im about to aquire a '24 and like its been said... pick your poison! They all have their issues but at the end of the day ill stand by GM since I feel they are the most reliable and easiest to work on imo.
 

ikeG

Oughta Know Better
Apr 19, 2011
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Western PA
www.facebook.com
Ive seen one weak in tank pump myself now. An occasional glow plug, a few turbo actuators, exhaust manifold studs broke, and of course the injector connectors

Sent from my SM-G990U2 using Tapatalk
 

pl_silverado

Active member
Jan 29, 2012
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43
I guess I'm throwing new lifters in mine proactively if i ever have the heads off, no sense in chancing it. Already did a built trans and compound kit, 4k miles later the actuator failed. Getting all my crap together to swap a 2024 turbo with a 10 blade into it now.
 

Durabiopwr

New member
Aug 2, 2025
11
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3
Eastern washing state
Very interesting. Anyone have any theories on why GM would change it from a design that worked well for so many years?

Same reason they went to 8mm exhaust manifold bolts rather than the 10mm that worked fine for YEARS. SAVE MONEY and get Mary Barra a bigger executive bonus.

Its all cost saving crap and 'value engineering' BS.

My guess is that some fail early due to slightly wrong lash setup when it left the factory. That would pound the lifter from day one. OR lifter supplier is not watching metalurgy/heat treat specs and are selling junk to GM. Just like the mis ground crankshafts on the gassers.

But with the old design and a better supplier those issues are negated. But that costs MONEY. Larger lifter take can more abuse from the get go.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
Fyi, L5P lifters are not hydraulic. Wouldnt have valve lash if they were. Others have cut them open and proved it as well

Forgot about this thread or i would have posted earlier.