Help understanding duramaxes since I am looking for one.

Discussion in 'GM Diesel & DuraMax' started by PantheraUncia, Sep 13, 2012.

  1. PantheraUncia

    PantheraUncia New Member


    I have been looking at duramaxes and have been looking at them online through autotrader:

    There are 31 trucks right now that meet the criteria I set in that link within 500 miles of my zipcode and I am not sure what I should be looking for as far as a good deal, bad deal, (if someone is trying to push a scam, etc).
  2. Pikey

    Pikey Moderator Staff Member

    I guess because I do not know much about the duramax I would look at prices and find out what the average is for the year, miles, options that you are looking for. Then go look at some trucks, when you find one you like take it to a mechanic and have them look at it. They charge between $25-$50 for this.
  3. ChevyBoy2009

    ChevyBoy2009 New Member

    My bro has a 08 Dirtymax CC and he loves it...the 08's have brake switch issues but its a cheap and easy fix...he paid 28k for his with 92k on it...pick one you like and go for it...i had a 01 Dirtymax and diesel got pretty expensive at 5 bucks a gallon so got rid of it...the allisons are strong runners!
  4. Sierraowner5.3

    Sierraowner5.3 New Member

    i dont know a whole lot, but make sure its got a allison in it!

  5. pmf608

    pmf608 New Member

    As far as Duramaxes go, they all either have the Allison or a manual transmission, so you'll be good in terms of the transmission. I don't know what year you're looking for, but the 2006 and newer would probably be your best bet. I just bought a 2003 Sierra 3500 cab/chassis with a flatdeck for $4250 here with 341,000km (212,000mi) on it. One big thing to look out for on the early models (2001-2004 with RPO code LB7 in the glove box) is the injectors. They had issues with them, and they're internal injectors (under the valve covers). Therefore, it takes a lot of work (and I think about $4000 if you have a dealer do it) to change a set of injectors if they go bad. I think the late 2004-2006 (LLY code) engines had a couple of different issues, but the injectors were mounted externally so they were a lot less difficult to deal with. Overall, I'd say they were better than the first generation.

    In 2006, GM came out with the LBZ Duramax, which had more power and a 6 speed Allison instead of the 5 speed that had been used previously. The LBZ continued through 2007, when they came out with the LMM (more power,etc. and only available on the new style trucks). My understanding is that some new style trucks had the LBZ and some had the newer LMM.

    The 2011+ trucks have the LML engine in them. This engine was designed to have more power and torque and meet stricter emissions standards by adding Diesel Exhaust Fluid (urea injection into the exhaust).

    Overall, the LB7 had the least emissions stuff on it, and would probably be the simplest one. The LLY had a good mix of reliability, power, etc. The LBZ and newer have better power but more emissions crap and computer controls. I've also heard that people can get pretty close to 20 mpg on the highway easily with the LB7 and LLY (and possibly the LBZ) due to less emissions equipment, but that the newer ones with the Diesel Particulate Filters and such tend to get considerably lower fuel economy. I haven't had mine long enough to give you any personal experience on this though.

    My advice would be just make sure that whatever truck you might end up buying runs smooth, shifts smooth and doesnt have any tapping or knocking noises. As long as those areas are good, you should end up with a pretty solid truck. I can say I'm very happy with mine.
  6. PantheraUncia

    PantheraUncia New Member

    Thanks pfm608 that was great information and helps allot
  7. aloxdaddy99

    aloxdaddy99 New Member

    Stay away from one that requires urea for emissions. I say this Nak cause than you are cutting into that savings we calculated the other day.
  8. Brews

    Brews New Member

    I found out the hard way about the injector issue with the 2001-2004. I would avoid them.
  9. LB'07-Z

    LB'07-Z New Member

    I wouldn't shy away from an 01-04 if the injectors have been replaced. Thats why I just bought my 02. The dealership i bought mine from had records that the previous owner had them replaced a year and a half ago. You also can take one to a Chevy dealer and have them test the injectors. I'vealso heard of the 03-05 having overheating issues while towing due to the hood design. If you will notice on the 05.5-07 classic the hood is alittle taller and allows the engine to cool easier. I went with the 02 mainly because I was on a budget and have wanted a Dmax for a long time but if money hadn't have been no object I personally would have got an 05.5-07 classic mainly because I like that body style.
  10. PantheraUncia

    PantheraUncia New Member

    Yep, I am going to do my best to stay away from a brand new one so I don't have to deal with the urea mess.... I think a 2010 will be the newest i am looking at.

    - - - Updated - - -

    So this brings up a good question that I would like an answer to. The fuel injectors on my gasser (5.3L) are about $100 each or $800 all together + install unless I do it myself.

    What is the cost (if you are out of warranty) on the injectors on a Duramax? I keep hearing something like $4000 installed? is it really that high? can you do it yourself? and what is the life expectancy of them?
  11. Brews

    Brews New Member

    The injectors in my 01 checked out fine at the dealership when I bought it, 30,000 miles later, and 500 miles from home pulling our 5th wheel, they went out. The dealership quoted me a price of $5,600.00 to replace the injectors and a regulator.
  12. PantheraUncia

    PantheraUncia New Member

    I just called my dealer and got some prices from the service department (Not that I would go to the dealer to have the work done, just looking for a reference point)


    • Injectors replace: $2800 (all 8)
    • Glow Plugs: $700 (all 8)
    • Tranny $5500

    5.3L Gas:

    • Injectors $2000 (most is labor) (all 8)
    • no glow plugs
    • Tranny $3400

    Other things to keep in mind...... The Alison lasts allot longer between rebuilds than a 4L60E, so the $2000 up charge is not that important because you are going to be x more miles out of it before it needs a rebuild. They also told me that they hardly ever need to replace glow plugs so that is not a big issue.

    Injectors is another story. It really is not that much more expensive than a 5.3L Gas engine. If I get 250,000 miles out of my gas injectors, how many will I get out of the dmax? (I know diesel is dirtier so I assume it would be more often?

    - - - Updated - - -

    So how many miles were on your Dmax total at the time of the injector replacement (30,000 + what was on it before you bought it?)
  13. Brews

    Brews New Member

    135,000 total.

    - - - Updated - - -

    I really liked that truck, but everything about a diesel is expensive. IMO you need to haul on a regular basis to justify the extra cost. My new truck is gas and I miss the torque on hills and the MPG is about 2-3 less, but overall I'm happy with it.
  14. ahmitchell1

    ahmitchell1 New Member

    The Lbz is a great motor and with the right bolt ons and tune you can get amazing gas mileage. Yes they are more expensive to maintain but worth it as they do last longer.
  15. ChevyHD

    ChevyHD New Member

    What are you planning to do with your duramax? If you don't add power, I highly doubt you ever need to rebuild your tranny. Plus for $5500 you can have a built allison that would hold 1000 horse.

    ^This guy is an Allison God

    And you can really pro long the life of injectors with the addition of two parts:

    A lift pump made by fass or airdog and a cat adapter that utilizes the stock fuel filter head and puts an adapter to allow you to use a 2 micron cat filter which is much cheaper. The fuel would be conditioned and put a lot less wear on your injectors.
  16. PantheraUncia

    PantheraUncia New Member

    Hi ChevyHD,

    Thank you for the information :). While I do not do this for a living, I have hauled Upright piano's in the bed of my 1500, I have also towed cars on dual axle trailers, and every now and then I have pulled tow behind cement mixers, I tried to put a full bed of soil in it, but there was a point where I was not going to let them put any more soil in the bed because my leaf springs in the 1500 were at their limit.

    The reason I put the cost of rebuilding the allison, is that I had to have my 4L60E (piece of junk) rebuilt at 183,000 miles. I was told that, that is pretty good for a 4L60E and it might very well be good for that tranny. As a truck owner, my expectation for a tranny rebuild would have been at 350,000 miles, not 180,000.

    I also keep getting told how expensive a diesel is. Well, if I bought a diesel today and sold it in 12 months, I would loose my shirt. If I keep it 12 or 15 years and don't need a tranny rebuild (same me $3000-$5500) that is one less expense I did not have to pay that I did on the gasser.

    Then with your suggestions and maybe a custom tune from diablo, if I can get the Dmax up to 22-25mpg compared to 15mpg on my 5.3L gas. Also taking into account I fill up my truck once a week (52) times per year, If I continue to drive the same way with the diesel, I might fill up 40 times per year.

    Than over 12 or 15 years, I have saved money buying the dmax. Most of the people than own 5.3L don't believe it is possible.
  17. ChevyHD

    ChevyHD New Member

    22-25 is pretty high I would say 20-22 hwy with a tune. Diesels are more expensive for a lot of reasons. 10 quarts of oil per change, fuel filters, injectors will go bad with LB7's and LLY's have head gasket issues and water pumps. Fuel is obviously more expensive as well. If you can justify owning one then, much like you said, it is worth it because they run for a lot longer. Every part on a diesel is heavier duty. If you are going to tune a duramax though, the best way to do it is EFI live. You can get anything you want. You get either a DSP5 or DSP2 switch depending if you want 2 or 5 tunes. I just got my tuning down and have 1.) Optimized stock (More timing, EGR shutoff) 2.) Heavy Tow W/ Turbo Brake +25 horse 3.) Light Tow W/Turbo Brake +50 horse 4.) +85 horse/Economy Tune 5.) 120 Horse Performance tune.
  18. elkhornsun

    elkhornsun New Member

    Gm has produced 5 different Duramax engines over the past 8 years and many have had their weaknesses. One of the best in an older truck is the 2006-07 LBZ engine. Its only weakness is in the fuel supply and a lift pump can correct many potential problems. The 2007 to look for is called the "Classic" and is different than the 2007.5 and later trucks.

    Stay away from any engine that has been tuned. It shortens the life of the engine and of the Allison transmission and repairs to either are going to be very expensive. Same applies to running oversize tires.
  19. GMTruckManiac

    GMTruckManiac New Member

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    I have been having trouble starting my 2002 duramax with 172k miles on it. Lately its been 0-10 degrees out with even colder wind chills. Went to NAPA and O'reillys and had them test the batteries and they both said they were fine. The battery on the drivers side tested out at 720 cranking amps and the passenger side tested at 623 cranking amps. Went to start it today at 10 degrees I decided to cycle to glow plugs twice, the first time the voltage gauge read 9V and for the second cycle it read 5V and slowly dipped down to 0V and started clicking. After 3 jumps to just the driver side battery i decided to jump both batteries and it started right up after a few cranks. Once it is running for a while and then turned off it will start right back up again, it is primarily having this problem after a cold night.

    I figure that I need new batteries but I was wondering if there is something draining the battery more than it should. Could this possibly be the glow plugs going bad and drawing too much power? Bad relay? Or something else?? Thanks ahead of time!!

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  20. LB'07-Z

    LB'07-Z New Member

    Have you considered plugging it in to keep the glow plugs nice aand toasty all night?

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