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Discussion Starter · #1 ·
Hey folks; I’m looking at getting an LML with around 130,000 miles. (2015 gmc2500) Cp4 is my concern (coming from a newer Powerstroke with the same achielles heal) - is there anything I can check before I buy it to test the pump or anything? - seems like a lift pump is a must, and is there any ‘disaster prevention kits’ like the Powerstrokes have? -
I’ll keep searching and reading but possibly buying this weekend or early next week so any input is greatly appreciated.
cp3 is also a possibility to switch to. Have to read the pros & cons(?) and depends on the price I can get the truck for when that happens (if)
thanks!
 

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Former GM Tech and parts
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I thought I had heard that S&S Diesel had been working on a disaster prevention kit for the LML trucks... I bought a higher mileage 15 and was concerned about the cp4 failing on me, but it went another 30k trouble free miles before I did my cp3 conversion in January. But I already had the cp3 so that helped the cost aspect too, and then got the Fleece conversion kit one night when I ran over there to talk to Jake about something else. I would recommend a lift pump for sure, I did a Fleece in-tank pump and it works great.
 

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Discussion Starter · #4 ·
I thought I had heard that S&S Diesel had been working on a disaster prevention kit for the LML trucks... I bought a higher mileage 15 and was concerned about the cp4 failing on me, but it went another 30k trouble free miles before I did my cp3 conversion in January. But I already had the cp3 so that helped the cost aspect too, and then got the Fleece conversion kit one night when I ran over there to talk to Jake about something else. I would recommend a lift pump for sure, I did a Fleece in-tank pump and it works great.
heres what I’m hoping!! Haha - how is it after the cp3. Beginner question but are there any disadvantages going to the cp3?

Thanks for the replies!
 

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Former GM Tech and parts
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Runs great, had to adjust the reg in the tuning a couple times to get it lined out but has been good for daily driving and towing my other truck around
 

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Hey folks; I’m looking at getting an LML with around 130,000 miles. (2015 gmc2500) Cp4 is my concern (coming from a newer Powerstroke with the same achielles heal) - is there anything I can check before I buy it to test the pump or anything? - seems like a lift pump is a must, and is there any ‘disaster prevention kits’ like the Powerstrokes have? -
I’ll keep searching and reading but possibly buying this weekend or early next week so any input is greatly appreciated.
cp3 is also a possibility to switch to. Have to read the pros & cons(?) and depends on the price I can get the truck for when that happens (if)
thanks!
I think the CP4 thing gets a little overblown to some extent. Sure there are failures but they aren’t all doomed to die either. Plenty of high mileage ones out there both Ford/GM. I personally only know one guy that has had a Failure and it was due to contaminated fuel. I have a bone stock 15 with 115K and no issues with fuel system so far. I just use additive every tank and change filters at recommended intervals. Downfall of the LML is at some point you’ll have emmission issues. I’ve one DEF heater replaced under warranty. Can get pricy to fix out of warranty. Overall this is the best pickup I’ve ever owned and has given me excellent service. I use my FIL’s 2020 L5P occasionally and it does have more power but the 15 does fine for my area. The 10 speed is nice but I’d about the older 6 speed Allison’s will be more reliable. Time will tell. Look at the values of the LML. They ain’t backing up much.
 

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BUY A LML?
I've not driven...for that matter even ridden in a later model. What I can tell you about my own LML (a '13 long-bed "dualie") ... ... .that it is by far the best vehicle I have ever owned. And that takes in a lot of vehicles since I started driving medium duty trucks in 1956.

True, I had to have some "adjustments" done to the pollution control systems (after one scary night when suddenly going into "limp mode" almost got my wife and I killed and the truck dstroyed....!).

And yes, I "bought into" the CP3 'scare" - had that done (no difference in operation).

Our primary use for our LML is long distance towing (our boat trailer and our "box" car trailer weigh bout the same - in the area of 11,000 lbs. (bumper hitch). On a typical "run" from the Prescott, Arizona area to either the boat ramp near Page, Arizona, or car show grounds in Los Angeles, my OVERALL mileage is around 10.5 mpg. (obviously MUCH MUCH better "coming down off the mountain" on the Interstates with the wind at my back......and much MUCH worse on the long up-hill grades (like the Needles To Seligman one on I-40)

We VERY rarely use it as a "2nd car"....given it is no sports car...I see no point in having a truck just for that.
 

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I am in the same situation as others in that I religiously run a good fuel additive. Buy fuel from quality stations. 300K on my LML and it's my daily driver.

I did have to do head gaskets, which hurt the wallet. At the same time glow plugs, water pump, pulleys, belts etc all done as the motor was already apart. ARP studs were used.

Been solid. Just regular maintenance like filters and fluid changes.
 
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