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03 gmc duramax with 350k (BBT) transmission fun

ClassicStyle said:
If the injectors and cp3 have been done recently, had its normal fluid changes and what not I don't know how afraid of it I would be, my worries would be in the rest of the truck falling apart.

I'd rather tow with a 350k lb7 than a 80-150k 6.0

I don't understand the love of the 6.0/8.1 for towing. Shitty gas mileage and 55 mph don't do it for me.

I'll take my tuned and deleted lmm over any other diesel/gas any day of the week.
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jekquistk5 said:
As a lb7 dmax motor owner, I can tell you to check the balance rates to see if the injectors are good or bad. As close to zero is the best number. Anything over/under +-4 is bad. Check when the truck is warmed up. 1900ish for a set if bad. It isn't a bad job, just time conduming . Everything on the Allison is expensive. So if it hasn't been gone through recently I'd start saving to a rebuild.

That being said I love my truck and would pick it to tow anything over my dads 01 2500hd with the 8.1/ally.

The off idle torque is the only thing the 8.1 has on my truck.
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Not everyone needs a diesel to tow, especially if you are a "tow once or twice a month" type of guy (like some of us). In that case, I don't think you need to deal with the higher cost to purchase and the higher cost to own just to justify going 10 more mph up a pass and getting 5 more mpg's. If you tow a couple times a week or need it for work, well sure then it's a no brainer to go diesel, but I think it's dumb for the weekend warrior type of guy.

And saying the 6.0/8.1 gets crappy gas mileage towing compared to an LB7 is an incorrect statement as most I have seen will at most get 15 mpg's when towing (at most) with an LB7. Sure the 8.1 get 10 mpg's towing or empty, but guess what, when you need to replace the injectors in that it costs ~$200 and a couple hours of your time. Can you say the same for your diesel? Now, if you want to DD an 8.1, that's kinda stupid as then you are throwing money in the toilet for no reason with the mileage, that's why I said a 6.0 would be a good choice if you plan to drive it during the week to and from whatever you are doing.

Either way, there are pluses and minuses to every single truck depending on what you plan to use it for. You will most likely have to make a sacrifice somewhere, just depends on what sacrifice you are willing to give up with your truck. Hopefully some comments in this thread have given the OP some ideas on his own direction.

This is a pretty interesting thread to read through about buying a used diesel (look past all the typical pirate4x4 childish bantering back and forth). There are some actual good points for both gas and diesel that are worth noting:

http://www.pirate4x4.com/forum/tow-rigs-trailers/2320529-15k-tow-rig-what-would-you-buy.html
 
They say age is nothing but a number, and I agree when it comes to mileage anymore. I have a buddy who has 450k miles on a 2003 1/2ton Silverado. Everything drivetrain is still factory. Normal maint. and fluid changes are the only thing done. Now I know his may be a rare case, and he did not tow a lot of those miles.

Then again, I was in the same boat a year ago as you are now. And I ended up settling on a 2000 OBS C3500 6.5TD truck :whistle:
 
Kay86K5 said:
Not everyone needs a diesel to tow, especially if you are a "tow once or twice a month" type of guy (like some of us). In that case, I don't think you need to deal with the higher cost to purchase and the higher cost to own just to justify going 10 more mph up a pass and getting 5 more mpg's. If you tow a couple times a week or need it for work, well sure then it's a no brainer to go diesel, but I think it's dumb for the weekend warrior type of guy.

And saying the 6.0/8.1 gets crappy gas mileage towing compared to an LB7 is an incorrect statement as most I have seen will at most get 15 mpg's when towing (at most) with an LB7. Sure the 8.1 get 10 mpg's towing or empty, but guess what, when you need to replace the injectors in that it costs ~$200 and a couple hours of your time. Can you say the same for your diesel? Now, if you want to DD an 8.1, that's kinda stupid as then you are throwing money in the toilet for no reason with the mileage, that's why I said a 6.0 would be a good choice if you plan to drive it during the week to and from whatever you are doing.

Either way, there are pluses and minuses to every single truck depending on what you plan to use it for. You will most likely have to make a sacrifice somewhere, just depends on what sacrifice you are willing to give up with your truck. Hopefully some comments in this thread have given the OP some ideas on his own direction.

This is a pretty interesting thread to read through about buying a used diesel (look past all the typical pirate4x4 childish bantering back and forth). There are some actual good points for both gas and diesel that are worth noting:

http://www.pirate4x4.com/forum/tow-rigs-trailers/2320529-15k-tow-rig-what-would-you-buy.html
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I get what your saying, but I've DD a Duramax for last 5 years, my lb7 had a efi live tune, unloaded got 17-19mpg, far better mileage than any gas truck I've owned before.

The money spent on maintaince is worth it to me for a truck that has a lot of get up and go, and transmission that shifts nicer than any 4L.

My lmm now doesn't get quite the mileage of my old lb7, but deleting dpf and regen, and a nice tune will take care of that, with its dpf safe tune now it will out run my fathers srt8 challenger. Once I delete it will burn the tires off into third gear.

It was double the price a comparable gas truck, but I have zero regrets, it does everything I want, I can tow anything I need, diesel fuel is cheaper than 89-91 right now, it has a tremendous more power, and gets better mileage
 
Always consider worst case scenario on a used vehicle. Buy the 350k mile truck and the dmax does fail, is it worth spending 10k+ to replace the engine in a 350k truck. Nope. There's a 03 4x4 crew local for $6500 with 315k miles and new injectors less than a year ago not sure what they want for the one you are referring to.
 
Like anything else it depends on what you want to use it for. I currently own a 98 Cummins with a 5 speed and 04 Suburban with the 8.1L. The Cummins is good for hauling long distances and mileage but the ride and comfort comes in a distant second to the Suburban. We went camping in Maine with the Suburban one Summer and it got 12+mpg. And it was the right rig to haul a family of five and all their gear. The 8.1L Suburban is an interesting vehicle in itself because technically, it is a 3/4 ton but the 8.1Ls got a 14BFF rear axle. The transmission is a 4L85E and it gets better mileage than an Allison. Suburbans can also come with 3.73s or 4.10s. This one has the 4.10s which is perfect with a set of 255/85R16s (33.5s). It pretty much does everything for us and is usually the go to rig.

The other point that should be made is whether this will be a daily driver or not and how far it will get driven. If it will be a daily driver and your commute is more than 40 miles (roundtrip), I would say get a nice riding, diesel. If this will be a daily driver and the commute is less than 40 miles, I would say go 8.1L. The 6.0L is not even a choice to me. It is a high rpm motor where the 8.1 makes it power down low and never seems to break a sweat. That said, I will say my favorite vehicle that I have owned is an 07 Classic Duramax CCSB. It rode nice and pretty much did it all with the LBZ diesel. I believe the stock torque rating for it was 650 ft/lbs of torque. But I sold it because I could own the 8.1L Suburban for less than half of what those go for and it does everything that that truck did, maybe more (3rd row seating).

So, in a nutshell, think about what you are going to use it for and make your decision accordingly.
 
Here's the outlook from someone at a dealer. Lb7's are pretty solid as long as it's had the original injectors replaced with the newer design. Beyond that it's only as good as it has been maintained. That would be evident for the rest of the truck too. I've had then through the shop with 450k on them running like a top. But those guys took maintenance to an ocd level . They had replaced some items a couple of times. Ball joints, idler & pitman arms, u joints and other items. They can last. But I've seen some with 100k that are beat to hell too.

Get maintenance records. Hell take the vin to a local dealer and have them run the warranty history. It will still show in GM's system despite the age. If it had injectors done under warranty or the special coverage they had on them you'll know. Buyer beware.

I do know this, pre-emission diesel trucks regardless of the make sell fast at our store. We just took a cream puff 2006 3/4 ton crew and it sold just as soon as my guys got done cleaning it up.

Now on the debate to diesel or gas. Personally I'd search for a 8.1 truck, burb or avalanche. Yeah it sucks fuel like a whino on a bender, but your operating costs are less in the long run when you factor in the higher cost of maintenance for the dmax. When diesel fuel cost goes back up it will widen that margin too. That makes sense for a part time tow rig. At least for me. If the truck is going to be full time tow duty then get the dmax. That being said just to illustrate the torque of the 8.1 I've passed many a diesel truck pulling a fifth wheel up mountain. Grades out here driving a class a motorhome with a 8.1 Allison combo tipping the scales right at the 22,000 gvw rating. Those beasts still got 8-10 mpg. Same exact 8.1 the trucks got. No additional tuning or other tricks. Not bad considering earlier rv's running 454's and only at 16,000 pound gvw might be lucky to get 4-6 mpg. It would be my choice to go 8.1.
 
Thanks for the responses guys.
For me this will only be a tow/hauling vehicle. No dd.
one question on duramaxs, what do the 3 letter codes you guys keep referencing?
 
Engine series numbers. Lb7 01-04, lly 04.5-06, lbz 06-07, lmm 07.5-10 lml 10 +

Lb7 are labor intensive to get to injectors
Lly has a re defined valve cover, Injectors no big deal, have injector wiring harness issues
Lbz last series before emissions cracked down
Lmm first with emissions, uses regen
Lml first to use urea (def)
 
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ashman said:
Thanks for the responses guys.
For me this will only be a tow/hauling vehicle. No dd.
one question on duramaxs, what do the 3 letter codes you guys keep referencing?
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Russell did a good break down of all the years for them a while back. I`ll try to find it for you. My Lb7 has 250 thousand miles on it...runs a strong as the day we got it! Actually better. We added 65 hp program to it years ago...we did replace the injectors last fall but for the most part it has been by far the best truck I have ever had!
 
max 02 said:
Russell did a good break down of all the years for them a while back. I`ll try to find it for you. My Lb7 has 250 thousand miles on it...runs a strong as the day we got it! Actually better. We added 65 hp program to it years ago...we did replace the injectors last fall but for the most part it has been by far the best truck I have ever had!
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Found what Russ posted....


https://ck5.com/forums/threads/duramax-engine-swap-what-year-of-engine-is-best.323856/#post-3589500
 
Thanks.
so, if I'm trying to do this cheap I should be looking for an lb7 that has had the injectors replaced?
 
ashman said:
Thanks.
so, if I'm trying to do this cheap I should be looking for an lb7 that has had the injectors replaced?
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I found a lb7 truck for my son 2 years ago he paid 1000.00 bucks for it and the injectors had been replaced! But not to likely to find a deal like that again.
And it needed a pile of other repairs... we knew that when we got it though...I have it all documented in the diesel section on here. On any Duramax you look at check the transfercase oil level.

Search pump rub...that will keep you reading for awile!

Buy the newest Duramax you can afford. They all have their quirks, but everything can be fixed!
 
Thanks for the suggestion to give the vin to a dealer. Turns out the injectors were replaced at 50k miles and then again at 200k. No head gasket work
 
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Regardless of nada I wouldnt give over 5-6k for any 350k mile diesel without some extensive maintenance records. I've bought all the big diesels under 10yrs old for 2-3000 and fixed what was broken. At least I knew what I was getting and what had been done to it.
 
well... I bought it. :)
I was able to get it for 6k which was pretty good compared to what else I was seeing around here. Interior is in fantastic shape, exterior not so much. Lots of rock chips and some "redneck pinstripping", but nothing I can't live with. The kicker was that the entire front end has been replaced and is still under warranty.

I'll post some pics later. Thanks for the advice guys! Hopefully I made a good choice.
 
I bought a 92 1/2 ton blazer 6 years ago for the equivalent of 289 dollars. Blown rear axle, steering system loose as a 60 year old hooker. Truck was used hard and put away wet. Replaced the axle and the steering parts. Now has 300687 miles on original motor and trans. Still running strong with a/c blowing 39 degrees. I LOVE THIS TRUCK. If I can get that many miles out of an abused 350 gasser that Duramax should go at least a half mil. before any trouble.
 
pics time!
Bbt3.jpg


Bbt2.jpg


Bbt1.jpg

sorry, my car is in front for scale. :)

Pics make the paint look much better than it is, but so far, so good. For $6K, I think I did alright.

Now to start fixing the little crap that annoys me. First up, the tailgate rattles a bit. It looks like there are supposed to be pads above the latches but they are missing. Gonna look into finding those asap.
 
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