What has FAILED? - (2021) L5P Duramax Review

What has FAILED - (2021) L5P Duramax Review
https://thedpfdeleteshops.comWhat’s up guys, so I just wanted to do a quick video here now that I’ve somewhat started to figure out this whole video audio, putting it together trying to be slightly more entertaining. Anyway, I wanted to do a review on my 2021 Chevy Silverado 3500. The reason I wanted to do this review was just because there’s not a lot of them out there on this little group of years. I think what I’m going to say is probably only applicable from like midway 2020 to 2023.
I know it might have been the 23s, but I know for sure 24s. They changed up a few things and it’s kind of a little bit of a different setup on the new L5PCE. So that being said, why me? Well, I put a lot of miles on these trucks. I do hot shot trucking, so in about 2 and 1/2 years, I’ve put 224,000 miles on this truck. I have another truck same year same everything except it’s a cabin chassis truck, engine, rear ends all the same.
The only difference with the cabin chassis is, it has a 10-ft bed. It has a 40-gallon tank instead of a 36-gallon one, has a slightly bigger DEF tank, and the spring pack on the rear end’s a little different other than that they’re pretty much the same exact truck. And that being said, since I have two of them, I’ve got to see what has failed almost simultaneously at the same mileage points on both trucks. So I’m not just speaking of, you know, I didn’t just get a lemon. I actually have two to compare side by side.
So that being said, I guess just to be upfront, I went from an 06 3/4 ton Duramax, you know old trusty and I jumped to these for my business. I’ll give you what I do and don’t like right off the bat. So I do like the 10-speed transmission. I don’t like how the shift points are set up from the factory when it comes to downshifting. I live here in Colorado. I do a lot of running up and down the mountains.
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I can tell you if you let this drive itself down a mountain it’ll probably blow itself up, it seems to want to downshift and hold red line. I mean horrible high RPMs on this truck, so I know a lot of guys do it, but some guys don’t. I’ve always even in M6, with the six-speed transmission, even on the mountains, I still put it in manual mode and control the gears myself, and I highly recommend doing that. With these 10-speeds, they ride really smooth for a one-ton. Chevy seems to always kind of be above the rest when it comes to ride quality and other than that. It’s just another Duramax. You know nothing cool about the interior.
I know the new interiors are way nicer than this one, so that’s a nice upgrade. But yeah. I guess I’ll get to why most of you are probably here is you, you probably want to hear what issues have I had because being, as you know, the 2021s, 2020s, 2022s are getting to be a few years old. I’m sure a lot of people out there are starting to look at these slightly used trucks. Now, like I said, I put a lot of miles about 10,000 miles a month on these trucks, so I’ve actually put you know what most people put in the lifetime of owning a truck on these trucks in about 2 and a half 3 years. So I can I’ll pull up my repair records for my company, and I kind of talk about a few things that I know for sure have gone wrong on both trucks simultaneously, which to me, is an indication of a recurring issue that most people are probably going to face they’re not going to be one-off issues.
Both of these trucks I’ve owned since brand new. So that being said, yeah I’ll jump right into it here. I’ll pull up my maintenance record here. So, let’s see the first issue. I know both trucks shared okay at about 40, 50,000 miles. AC failures, so the pressure sensor on the AC went out on both trucks almost like clockwork at the 40-50,000 mile range. That was still covered under warranty, not a big issue. It’s like a one-day fix and since they’ve been fixed, they haven’t gone out again. So I don’t know if GM fixed something there.
Also at about 50,000 miles, fuel rail pressure sensors and connectors. These Chevy seem to have this issue with a lot of the sensor connectors. The rail pressure sensor, both trucks lost it. I would say yeah right about 50-60,000 miles and you just start getting low fuel pressure codes or some other codes about circuit voltage on the pressure sensor and once again, for the dealer, simple fix. I haven’t done it myself. One truck did have the sensor go out twice, but I feel like there might have been some errors during the first repair.
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So yeah, that’s also gone out on both trucks. But again, if you were to do that repair yourself. It’s four or five hours of labor and I think 200 bucks for the sensor and that’s it. Injector pigtails, okay. So this is a big one. A lot of guys have been putting videos out. I’ve had number eight number, seven and number four. The only three I’ve had issues with one truck had eight and the other truck had four and seven. It’s just that pigtail that clips into the top of the injector. I don’t know what’s going on there they get loose. The one truck I was out of state and I was hauling at the time, so I kind of rode it out longer than I should and it ended up actually cooking the top plastic of the injector, so they had to replace the injector with it. So that is another thing. If you could fix this yourself, the pigtail is like 30 bucks from the dealer. It’s two wires. Splice connect you’re fixed. I’ve done it on the side of the road in 20 minutes on the other truck once again.
Annoying, but not a huge issue depending on which injector though you kind of have to pull some plastic covers off. It can be a little bit of a hassle, I mean don’t get me wrong, but again to me not a huge issue. Let’s see what else I’ve had going down my list here, so that’s pretty much up until 100,000 miles. Those are the only issues I had fuel injector, pigtails, and AC pressure sensor and fuel rail pressure sensor.
Now I will tell you so on one truck at around 140,000 miles. I started having transmission issues and I ended up having to put a new valve body in the transmission the other truck at about 103,000 to 104,000 miles, something like that. It actually toasted the entire transmission. So a lot of you are here are probably curious about that 10-speed. So yes, out of all fairness, I’ve had to replace the transmission in each truck. So the one truck we replaced the transmission at, like I said, 100,000 to 105,000, 110,000, something like that. Now I will tell you surprisingly, the transmission itself is only 3,600 bucks from the dealer. What sucks about the 10-speed is I’ve yet to find anyone who’s actually doing like built ones that are affordable. I mean the best upgrade I found from any of the reputable tranny builders out there. It’s like a $10,000 just for the transmission and to me it’s I can replace it almost three times before. I could justify spending that and that’s once again, these are new transmissions in the Duramaxes, so who knows how long their built ones actually hold up compared to stock. Now, in fairness, you know my trucks, tow 99% of the time and 95% of that they’re towing extremely heavy so I feel like on the transmission thing.
I wouldn’t be too concerned about it if you’re not towing heavy all the damn time. I feel like I kind of put extra wear and tear on them and the one with the valve body. They did the valve body and then about 80,000 miles later the entire transmission just took a dump and I was just like they were thinking another valve body. I said no just replace the whole transmission and get it back to me. So that’s probably the biggest expense I’ve had with both of these trucks up until 200,000 miles was a transmission replacement on both of them. Now the only other issues I’ve had that I’ve only I haven’t had this issue on the cabin chassis, but the one that came with the bed on it. If you hit the rumble strips it’ll, actually set off like the ABS and the anti-lock and all kinds of speed sensors, if you ride on the rumble strips for more than a couple of seconds and I’ve talked to another guy with the GMC another guy at the Chevy and they’ve had the same issue, but my cabin chassis has never done it. So I don’t know it’s something to do with the trucks that came with beds. I don’t know what it is, but that’s kind of it really. If you think about it, I got through that in less than 10 minutes here.
h&s mini maxx tuner https://thedpfdeleteshops.comThat’s all the issues I’ve had in 200,000 miles on two different trucks for the most part, the one issue I’ve done videos before if you’ve seen them is the that’s happened on both trucks numerous times and it’s kind of infuriating is the exhaust manifold, bolts and gaskets. Now, this is a big issue going around. I don’t know why GM felt the need to do this, but sometime during the L5P years they made the exhaust stud size smaller and with the new exhaust brake from the factory. I don’t know if it’s pressure
, building up or these trucks just run at such high EGTs all the time, because they’re towing a lot, but I’ve talked to guys who don’t tow a lot. They’ve had the same issue. These studs are loosening up now. The telltale sign of this is when you have your exhaust brake on and you’re going down the hill you’ll hear this tiny little squeal. It sounds like it’s coming from the dash: that’s an exhaust leak and if you go look at my other videos, I’ve done a couple going into detail on how to fix it.
What the deal is and if the dealer tells you it’s normal, it’s not normal. They need to get in there and they need to tighten up those studs if you go to the dealer, when mine was still under warranty and it happened, they replace the manifold, gasket, studs everything since it’s been out of warranty, I just take the heat shields off. I get in there and I just snug those bolts up sometimes quarter of a turn and that’s it and no more problems, but it seems to happen every I’d say 30 to 50,000 miles, one side or the other starts loosening up, and you start to hear that squeal and if you catch it in time, you tighten it up, it’s not an issue. I did have my other truck when another guy worked for me. He was driving and he wasn’t quick enough to diagnose the problem and he ended up driving it until it actually blew out the gasket itself. So we had to replace the gasket and everything on that side, but that is probably the most notorious issue.
I’ve seen with these 2020 to 2023 Duramaxes and then I’ll get on to the final issue. The HP4 injection pump alright guys. So I’m going to try to do a video on this because I’m going to be replacing one here soon. So on my one truck behind me that you can see it has had, I knew it was coming. I started noticing metal shavings in the fuel filter. Maybe the last three or four filter changes now I know the HP4 was supposed to you know they replaced the CP4 and it was supposed to get rid of that injection pump failure problem and now it’s coming to fruition that it really didn’t because this isn’t the first one I had it at the dealer I was going to let them do it but it happened right after I had the tranny replaced on this truck. So I’m looking at $20,000 for dealer work on this truck in a year and I decided it was too much not that I think it’s unfair.
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I know dealer prices, mechanic wages, GM parts, I’m going aftermarket. I ordered a full kit that comes with the injection pump: eight new injectors fuel rails, fuel cooler, fuel lines, everything I ordered from XDP it’s like 3,800 bucks, and then I have done an injection pump on my 06. I’m sure this one isn’t the same, but I’ll figure it out and hopefully I’ll get a video put together on replacing that thing. But that is the final issue that I’m starting to see a lot of guys having and the dealer said mine isn’t the first they’ve seen so that would be the only other thing. I’d look out for guys is on if you’re looking at a used one. I don’t know I’ve seen videos where guys are claiming the failures happening at 100,000. I didn’t start seeing any symptoms of an injection pump failure on this truck till 190,000 to 180,000. Something like that and even then it’s it’s weird everyone has their opinions. Some people say a very tiny amount of metal shavings in the filter is normal. I mean we all know how they rate that stuff, I mean you’ll see manufacturers say losing half a gallon of oil between oil changes is normal and a lot of us don’t think that is acceptable. So I mean it is what it is, but I would if you’re looking at one and it’s over 100,000 and you have any questions concerns if look at the maintenance get the Carfax do what you can, but I wouldn’t be afraid to ask them to pull the fuel filter and let you you know cut it open, let you see it just to make sure, because these HP4 pumps don’t seem to be much. I mean I know guys with a CP4 pump seems like I know a guy that works for a company down the road for me, his company truck they’ve done. It they’ve replaced the entire fuel system three times now and that truck has like 150,000 miles on it. So that would be the only other issue.
That being said, for all you guys who aren’t Chevy fans, I’m still a bow tie, bow tie till I die type of guy. All I own is Chevys. An injection pump doesn’t scare me this compared to some of my other friends in the hot shot industry that are running Dodges and Fords. I’ve by far had fewer issues than all those guys. The Dodges were I’m not going to I’ll get into that. Some other video, but I’ll just say it seems like I’ve had fewer issues than most guys running the trucks as hard as I run them and once again, when it comes to like the transmissions and all that it might be a lot different story. If you’re not working them as hard as I work them, same with the injection pump, I know another guy who has quite high mileage because he drives all over the country for work, but he’s like a supervisor guy, so he’s kind of just driving to the job site, checking on dudes. He has like 175,000 miles and no transmission issues he did have a cooling system issue. He had the AC failure and no, he says, there’s no sign of injection pump problems, but that is what it is. So that being said guys would I recommend buying. You know this 2020 and a half to 2023 L5P with 10-speed? Absolutely.
Once again, I know a lot of guys in my industry. We all work these trucks really hard and my Chevys seem to have had fewer major repairs than most of my other counterparts. The only thing I think they’ve beat me on is these do not get the greatest fuel mileage. Towing they do fantastic, empty like when I’m not towing anything highway. I mean I’ve. Seen this thing cruising 80 miles an hour saying it’s getting 20 miles a gallon. I’ve done the math of the pump kind of adds up most of the time, but if you get something that’s not aerodynamic behind this truck, it will just drink some fuel. So keep that in mind, if you’re towing a big enclosed trailer, something like that, if you’re not brand loyal, I will be honest and say the Dodge and Ford guys seem to do a lot better on fuel mileage than I do. I average seven most of the time if I get like a connex container behind that, where I got four feet of brick wall standing behind my truck, I’m getting like 5 miles a gallon at 65-70 miles per hour. So that being said, I know this was kind of a long video. Hopefully you guys got some value out of it.
Hopefully, the audio and all this kind of syncs up and hopefully I can get some some video of this HP4 replacement and get that uploaded soon as well. Drop a comment, drop a like subscribe. Let me know what you think and yep see y’all later. Hopefully, you got something out of this bye.

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