Dmax How Good Is It?

walex · April 27, 2008

I'm looking to buy an 06 to 07 Classic GMC 2500HD 4x4 w/ the 6.6 Dmax and Allison tranny w/ 3.73 gears. What's your opinion on the combo. Are there any serious problems with this combo in either year model, is the mpg decent, and is an 07 that much better than an 06? I'll only be looking at the LBZ 6.6. I've always had brand X diesels and want to come back home to a GM.

Thanks,

Walex

BlackSilver · April 27, 2008

I'm in my second DuraMax. Decent engines, not better or worse than the other two, but the reason I've stayed in Chev's is the Allison transmission.

ATMINF · April 27, 2008

The new 2007+ and the Old 1999-2007Classic GMT 800 HD platforms share many things. There are some that have said that they are basically the same platform. I have not been able to put the two together and take a look, but the bottom line is that they are very similar. So long story short, the good thing about the 2006-2007 Classic HD D-maxs is that they had all the cooling issues fixed, no smog stuff, and the overall truck had all the kinks worked out of them. So if I were in the market to buy a 2006-2007Classic D-max vs a brand new D-max I would try and get a 2007 Classic.

THE BIGPUNN · April 28, 2008

you cant go wrong with either one. i dont think there is any difference. haggle your best deal. i love my '07. i just seen however, that GM is offering some good incentives on the 08's.

SLESierra · April 28, 2008

The new 2007+ and the Old 1999-2007Classic GMT 800 HD platforms share many things. There are some that have said that they are basically the same platform. I have not been able to put the two together and take a look, but the bottom line is that they are very similar. So long story short, the good thing about the 2006-2007 Classic HD D-maxs is that they had all the cooling issues fixed, no smog stuff, and the overall truck had all the kinks worked out of them. So if I were in the market to buy a 2006-2007Classic D-max vs a brand new D-max I would try and get a 2007 Classic.

LMMs over on Diesel place already passing 100,000 miles with no issues - People keeping their LMMs stock are not having any more issues with the engine than those running the LBZ (06-07). The Diesel Particulate Filter is the issue on some trucks that are running dirty programmers but other than that they are in the most part getting these worked out and most who run programming are deleting the regeneration mode and removing the DPF. And for someone to say the trucks had the kinks worked out may want to search the forums as the NBS vs OBS the issues are the same as there may be a rattle/sqeak here or there but the 2500 and 3500 are the same truck with the exception of the new body on top.

ATMINF · April 28, 2008

WV, as I do not own a D-max, I can only say what I have seen on the forums, or relay the information that I was told by people that own them. I would say that the NNBS D-max is still working out issues with the new emissions on them, (yes they are holding up well), and the problems that some are having are due to "aftermarket add-ons". Some issues that still have to be worked out , ( as per discussions I have seen or had with some D-max owners are) the fuel milage that is not as good as people "think" it should be for be a D-max, and the are some sheetmetal/paint issues that are still being"worked" out on the new platforms. Just ask people that have some of the darker paintjobs, and also putting little"dents" on the top of the sidewalls of the box. The sheetmtal seems to be thinner that the older trucks in the bed area, makeing it easier to dent a little. So while the older trucks had some problems, all I am staying is that by the 2006-2007 year most issues were worked out. We can agree that there are some small issues that need to be "fixed" with the current "new" HD platform. They are very good trucks, but like I said before, if I was in the market for a D-max, I would try to get a "new" 2007 Classic D-max or find a used one with low miles . I am sure everything will be worked out in a year or two, but the new D-maxs do have some small issues. Just my 2 cents, and thats about all its worth. Hope this clairfies what I was trying to address. Thanks!

BlackSilver · April 28, 2008

WV, as I do not own a D-max, I can only say what I have seen on the forums.

As I have owned both "classic" DMax/Allisons and a "NBS" DMax/Allison I can speak from first hand experience, not second-hand/third-hand information. I work my trucks hard, mostly "highway miles", and I'm not a fan of aftermarket gadgetry.

In my experience with both generations of trucks, the NBS/LMM is noticeably better in every category except fuel economy.

Fuel economy: Running empty, the LMM get's 1-2MPG less than an LLY and about 3MPG less than the 1st gen LB7.

Interestingly, under load (I pull a 13,000# trailer) the LMM gives me just as good or maybe slightly better mileage. I suspect this stems from the additional power, and also perhaps because the 6-speed Allison keeps the engine more consistently in the "sweet spot" on the torque/power curves.

Performance: The additional power and better power train management under load improves this generation significantly over previous generations. Even my wife (not a gearhead in any sense) comments on how much stronger this truck is over the previous ones.

Cabin comfort: First, the NBS is QUIET!. The difference in road noise, wind noise, engine noise, etc., from the "classic" to "NBS" is remarkable. GM clearly did their homework on this issue. I liked the old seats a little better than the new ones (they took off the armrest to make the seat back wider). The new dash (in LTZ, at least) is a great improvement. Gone is the "japanese plastic" look of the previous generations.

Build quality: There seems better attention to detail in the new body style. Doors close with a "clunk" instead of a "clank". Body panels line up better, the hood fits cleaner, and it just seems a step up in this regard.

Cargo area: They did some subtle changes in the bed area. First, it's two inches deeper than the previous generations. Second, they smoothed out a lot of the interior creases and corners, making the bed a lot easier to clean after hauling a dirty load (sweeping and hosing out debris).

Depending on how you use your truck (this is the 'HD' forum), some may still prefer the classic version for "peace of mind", but if your truck "works hard for a living" as opposed to daily driver/grocery hauler, I think you'll be well served to look hard at the LMM/NBS.

ATMINF · April 28, 2008

Blacksilver, I do like the new trucks, so let me put that out first. I just want to see how all the new smog stuff works out. Do you or have you seen any issues where the sheetmtal on the new truck seem thinner? Maybe on the dullays the beds is a little different? I know on a friends new truck he stated he put a lttle dent on the bedframe by leaning on it. Does that seem like the case in your new truck vs old one? Thanks!

SLESierra · April 28, 2008

Atminf on the 2500 I have had straps down over the side of mine and it has not dented the bed. I went out just now and pressed on the side but I do not have a truck to compare with seems pretty sturdy. However my 1500 I had it was thin up you could flex it but this one seems thicker at the top of the bed. I understand if you are listening to the forums but remember most of the time on forums you read the complaints and a small percentage of those complaints. And also the last LBZs I have a friend who has one and his mileage is not the greatest either so I would assume most of the mileage lost to modern diesels is due to Ultra Low Sulfur Diesel somewhat and the rest on the DPF on the LMMs side. I have a Powerstroke work truck (Not My Choice) with the 6.0 and it also has suffered fuel economy loss over the last couple of years as the fuel has changed.

ATMINF · April 29, 2008

Thanks for the input guys. I have heard the Low Sulfer stuff is effecting the milage, I was not sure how much the regen/smog stuff was effect it also. All in all good to know. Maybe the HD trucks have "better" sheet metal on the beds? Thanks for the info!

BlackSilver · April 29, 2008

Do you or have you seen any issues where the sheetmtal on the new truck seem thinner? Maybe on the dullays the beds is a little different? I know on a friends new truck he stated he put a lttle dent on the bedframe by leaning on it. Does that seem like the case in your new truck vs old one? Thanks!

Haven't seen any issue with thin sheet metal on mine. Seems just as solid as my previous two (2001 and 2003) Chevs. Certainly don't feel any weakness by "leaning on it". Overall the body seems more "solid" to me, compared to the two previous ones.

SLESierra · April 29, 2008

dang read my last post there - so much for posting and talking on the phone - sounds like I am a skipping record LOL

walex · April 30, 2008

Thanks for the input guys. It sounds like most of what has been posted is good on the 06-07 OBS trucks although they may not be as refined as the NBS HDs. Although I own Chevy & GMC 1500s I have never owned a HD with Dmax. Just thinking about the troubles with the PowerStroke 6.0 I wanted to be sure I did my homework on the Dmax before making a decision. I heard there were a lot of problems with heads on the earlier Dmax, was this related to the cooling issue that was posted?