GMT800 LLY/LBZ reliability in stock form

[redhat]

I am looking at trucks, specifically GMT800 3/4 ton so 2500HD or even 3500. I want to buy a clean truck, oil it every year, and keep it for a good long while. I prefer the GMT800 interior to the plastic-laiden GMT900 (no offense anyone!). Definitely want a Crew Cab and leather (heated seats, mirrors, etc.).

Initially, out of reliability sake, I have been looking for a LQ4, but finding a Crew Cab, LQ4 with the amenities I want is tough. I know a LS 6.0 would go a long long time. I find Duramax models to be much more available in nice shape.

How reliable are the LLY/LBZ in stock form? I wouldn't have an issue with deleting an EGR, but if I could keep it stock without any major overhaul besides maintenance/injectors/glow plugs, I'd be happy. Do these year Duramax go the distance? I wouldn't even be that interested in a tuner or anything. Just want it stock. Heck, I'd even keep the factory airbox on (I am a BITOG guy FWIW).

Might be nice to have the Diesel power too as some day I do want a 25-30ft camper.

I know the diesel world is more expensive maintenance wise, but its a trade off, right? Don't have any problem with maintenance if it isn't going to be un-reliable.

 

[JohnnyJohnson]

Well I've had a Duramax since 2006 only 3 problems with it the oil cooler lines have leaked twice. Stealership wanted $800 to fix it each time. Now the Driver door ajar sensor $600. Other than that nothing. All this new sensor computing stuff on new vehicles is crap. As for hauling a 25 to 30 camper trailer a good V8 will handle that. My Duramax is pulling a 14,000 Lbs. DRV fifthweel. with zero issues towing that weight it delivers a pretty consistent 13 something MPG. I do as much maintenance on it as possible they want over $130 for an all synthetic 10 quart oil change which I do for $45 and $130 for a fuel filter which I do for $25. Stock air filter dealer over $100 I do for $38. The 2006 was the last year that didn't have to use DEF.

 

[MacManus99]

In my neck of the woods, people are quite proud of their high mileage/questionable maintenance diesels. Especially a pre-emissions diesel. I personally struggle to find the value over a gas powered 3/4 ton that will tow the camper you mention with ease.

I towed 14,000 lbs. with both my 2006 Cummins diesel and my current 2016 GM gas. I'm in no rush to go back to diesel.

 

[redhat]

In my neck of the woods, people are quite proud of their high mileage/questionable maintenance diesels. Especially a pre-emissions diesel. I personally struggle to find the value over a gas powered 3/4 ton that will tow the camper you mention with ease.

I towed 14,000 lbs. with both my 2006 Cummins diesel and my current 2016 GM gas. I'm in no rush to go back to diesel.

Do you have a lot of hills where you tow? I feel like 14,000 would kill a 6.0 on hills.

 

[ls1mike]

I have a 2017 3500HD gasser. I tow close to 8000lbs all over Washington, Idaho, Oregon, Montana and Wyoming.
My 6.0 does fine with 8000, but 14,000? I am gasser all day long guy, but if I were towing over 10,000lbs regularly I would have a diesel.
With 8000lbs I maintain the speed limits (well 65, I don't like to tow faster than that) with no issue. I don't think I would want to do 14,000 out west. The flats? Maybe.
The LBZ, if you can find one is the probably the best Duramax made.

 

[clinebarger]

I have over 420,000 miles on my (Stock Fueling, Boost, & Timing) 2006 LBZ. The EGR Cooler is simply blocked & EGR low flow DTC's have been turned off via HP Tuners.

*Trans Cooler lines leaking is an issue....On my second set & needing a third.
*Drive Belt, Idlers, & Belt Tensioner need replaced every 100,000 miles.
*Both Thermostats need replaced at 150,000-200,000 miles with OE GM (Isuzu, Made in Japan).
*The rubber sections of the fuel feed line will get soft at the crimps & literally get sucked closed under WOT causing Low Rail Pressure DTC's & Limp Mode/Reduced Power Mode. Installing a FASS or Air Dog Lift Pump/Filter assembly will eliminate this issue. Duramax trucks do not have lift pumps from the factory & rely solely on suction created by the CP3 Pump to draw fuel from the tank.

Like JohnnyJohnson.......My driver door latch switch acts up as well, The dome light won't come on when I open the door & the Radio won't shut off when I open the door the first time.....But If I close & open the door again, It works.

 

[MacManus99]

Do you have a lot of hills where you tow? I feel like 14,000 would kill a 6.0 on hills.

I may have fibbed a little bit. Bobcat T-250 weighs just over 9k, trailer weighs about 3k-3500. So that means I'm dragging 12.5k just west of St. Louis. Its no Rocky Mtns, but it ain't exactly Kansas either. Also note that this open trailer does not catch the wind like a sail.

Is there a performance loss compared to a diesel? Absolutely, but it still pulls the load just fine. When towing, more power is just a convenience. Is that convenience worth the considerable markup for diesel? I suppose that is for you to decide. For me, I would have to be towing a lot more than I am to justify it. As I said, I don't miss my Cummins at all.

 

[ls1mike]

I may have fibbed a little bit. Bobcat T-250 weighs just over 9k, trailer weighs about 3k-3500. So that means I'm dragging 12.5k just west of St. Louis. Its no Rocky Mtns, but it ain't exactly Kansas either. Also note that this open trailer does not catch the wind like a sail.

Is there a performance loss compared to a diesel? Absolutely, but it still pulls the load just fine. When towing, more power is just a convenience. Is that convenience worth the considerable markup for diesel? I suppose that is for you to decide. For me, I would have to be towing a lot more than I am to justify it. As I said, I don't miss my Cummins at all.

Not having the sail back there makes a big difference. I like my 6.0 just fine and suit my needs. It is anvil reliable with a 4L80E or 6L90E. I just couldn't imagine 14,000 lbs out west at like 6000 to 8000 feet if I were doing it often. I think my 17 is rated for 13,700. I always talk about getting a diesel but I really don't need one. I will take the ease of the gasser vs the current emissions diesels any day towing under 10,000lbs.

What year was your Cummins?

 

[ls1mike]

Redhat if you are towing a 25-30 foot trailer I can't imagine it will weigh much more than mine and I am really happy with how my gasser does.
I started with and 02 2500HD with 4L80E and my current truck is 17 3500 HD with 6L80E. My trailer is 35 feet 10 inches overall combined loaded for camping I am just shy or sometimes a bit over 16,000lbs.

 

[MacManus99]

You have quite a nice setup there.

What year was your Cummins?

My Cummins was a 2006, backed by the G56 6 speed. Engine performed well, and I loved having a manual trans. I hated pretty much everything else on that truck.

 

[ls1mike]

You have quite a nice setup there.



My Cummins was a 2006, backed by the G56 6 speed. Engine performed well, and I loved having a manual trans. I hated pretty much everything else on that truck.

Thanks It has served us well. I keep a log of miles towed, mostly for the trailer. I have towed this one just over 40,000 miles in the past 8 years. 4 sets of tires, 1 sent of brakes, 1 set of wheel bearings. It finally give me my fist big issue. The main slide is jerking when you put it in or out. It is like 3000 to 4000 bucks to fix. So I may trade it in. It is paid for so I don't know yet. I am going to try a couple things with it before I throw in the towel.

Got it. I have towed my trailer with my buddies 17 1 ton Denali Diesel. It feels like my truck (for obvious reasons) but at my weight it wasn't enough of a difference, to me at least, to justify the 63,000 dollar price tag. I do know some folks who have gone from diesel to gas, because of how they use the truck. It is nice to know how much you tow and that you are happy. I was recently looking at a 9800lbs gross trailer. Makes me less squeamish. LOL.

 

[BeerCan]

I want to go back to gas so bad. The Ford 7.3 is calling its siren song to me but I am afraid my trailer is to big.
I like a nice quiet ride and I am afraid of the noise a gas engine makes when towing. Does your gasser seem loud when towing heavy?

Here is what I am towing, I am afraid it's to much for a gasser

 

[MacManus99]

I want to go back to gas so bad. The Ford 7.3 is calling its siren song to me but I am afraid my trailer is to big.
I like a nice quiet ride and I am afraid of the noise a gas engine makes when towing. Does your gasser seem loud when towing heavy?

Here is what I am towing, I am afraid it's to much for a gasser

Yes, mine is loud and sounds angry when towing.

I will admit that the RPMs and throttle needed to tow was a bit of an adjustment, both in driving style and ignoring my mechanical sympathy. At the end of the day, it is far better to let the engine rev than it is to lug (regardless of diesel or gas). I also remind myself that these engine will turn 4500 rpm for days on end without significant damage or wear.

At this point, it sounds like you want the diesel, and man, there is absolutely nothing wrong with that. I fear that if you bought gas, and ever got into a situation where it was over-worked, you would immediately start kicking yourself for not getting a diesel. So, if you can swing it, I think you should settle elsewhere.

As Cline stated, the LBZ Duramax is probably the pinnacle of that engine, although every truck of that age and associated mileage will have its issues. It would be wise to have some money set aside for unforeseen repairs, regardless of make, model, and fuel type. Just set aside more if you do go diesel.

 

[ls1mike]

I want to go back to gas so bad. The Ford 7.3 is calling its siren song to me but I am afraid my trailer is to big.
I like a nice quiet ride and I am afraid of the noise a gas engine makes when towing. Does your gasser seem loud when towing heavy?

Here is what I am towing, I am afraid it's to much for a gasser

View attachment 36385
View attachment 36386

How heavy are you? I don't find is super loud or uncomfortable.

 

[dareo]

The last few years of the GMT 800 are pretty good. The issues are easy to identify and fix. I had a 6.0 gas 2500 and it was solid reliable. My van has the LLY duramax and it is very impressive in performance. It will fire up instantly in this cold and run smoothly. Gas truck would get 12-15, LLY van can do 19-20 highway.

 

[redhat]

Redhat if you are towing a 25-30 foot trailer I can't imagine it will weigh much more than mine and I am really happy with how my gasser does.
I started with and 02 2500HD with 4L80E and my current truck is 17 3500 HD with 6L80E. My trailer is 35 feet 10 inches overall combined loaded for camping I am just shy or sometimes a bit over 16,000lbs.
View attachment 36374

Thanks and nice setups. After having your newer 6.0 with the 6L, does it make the 4L and the Gen III 6.0 seem underpowered? How did your 02 do?

Is the quality on the newer trucks like your 17 on par with the old GMT800? I am not as much a fan of the GMT900 trucks interiors.

My wife and I, were young, and I want to have a crew cab truck that’ll be able to take us and our family, a 25-30’ camper around the area camping and maybe even long hauls. Additionally what really sparks my interest is a 25’ camper with those decks on the front of them for loading ATVs. Would love to go camping with two ATVs in tow.

I am not sure how much that would all weight. A camping trailer and two ATVs. Maybe a 6.0 LS would be plenty? That would prob be the heaviest I’d ever encounter. Other major hauling would maybe be my Dads car hauler trailer with my Regal on it. Or maybe even another 3/4 ton truck on it. But I can’t see the regal on that trailer being over 8k lbs

 

[ls1mike]

Thanks and nice setups. After having your newer 6.0 with the 6L, does it make the 4L and the Gen III 6.0 seem underpowered? How did your 02 do?

Is the quality on the newer trucks like your 17 on par with the old GMT800? I am not as much a fan of the GMT900 trucks interiors.

My wife and I, were young, and I want to have a crew cab truck that’ll be able to take us and our family, a 25-30’ camper around the area camping and maybe even long hauls. Additionally what really sparks my interest is a 25’ camper with those decks on the front of them for loading ATVs. Would love to go camping with two ATVs in tow.

I am not sure how much that would all weight. A camping trailer and two ATVs. Maybe a 6.0 LS would be plenty? That would prob be the heaviest I’d ever encounter. Other major hauling would maybe be my Dads car hauler trailer with my Regal on it. Or maybe even another 3/4 ton truck on it. But I can’t see the regal on that trailer being over 8k lbs

What I can tell you is the current truck is 60 more hp and 20 more ft/lbs of torque, but the 6 speed and 4.10s make a huge difference over the old 02 with 4 speed and 4.10s. 1st gear in the 2017 is very nice. The 02's first gear was like staring in the 17's second gear.

The old 02 did fine it just required more go pedal so more RPMS. An example is going up Vantage in Washington. It is in the desert in the summer it gets hot (90 to 110). It is about 10 miles of 4 to 7 percent grades. The 02 would see 4000 to 5000 RPM to hold 60 going up it. The 2017 will see about 3800 rpm to go 65. That is fully loaded, both with trans temps around 170 to 190. Snoqualmie pass, over the Cascades which is only 3015 feet has some 7 percent grades so not horrible. The 02 would see 4000 rpm to go 62 ish. This summer I went over it at 70 in the 17 (and I don't go 70 often towing, just wondered how the truck would do) I didn't see over 4200 rpm.

I feel the later trucks like my 2017 are put together better than my GMT800, the interior is nicer and put together better. My one complaint is the sheet metal is thinner. They have the updated manifolds and bolts which are supposed to prevent the exhaust manifold leaks. I changed the bolts out to ARP early on to reduce the chance of the heads breaking off and causing a leak. It has integrated brake control, grade braking and hill start assist. Long story short, I would not go back to a 4 speed/6.0. If you are looking you need to find a 6 speed with 4.10s.

 

[redhat]

Gas would be way easier to maintain. And I just realized this. The 6.0-6speed 15+ is not direct injection. Good old NO DoD Gen IV port fuel. Wow that is IMO the pinnacle of GM small block.

 

[redhat]

Is the 15+ 2500HD coil spring or torsion bar front end?

 

[ls1mike]

Torsion bar