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Duramax and 2500 HD info

Discussion in '1982-Present GM Diesel' started by BadDog, Jul 27, 2002.

  1. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Well, this is my first visit to the diesel forum. Never had a reason till now to look at anything deisel related. Anyway, I've now got a '02 2500 HD 4x4 with Duramax and Allison. Deal was just too good to pass up. Only thing I've done so far is step up to 33 ATs (yes, no lift, small mods to front inner liners) and I love this thing. It is truly a beast, but now I officially own a vehicle that I have no prayer of working on. /forums/images/icons/frown.gif

    Now my question, where is the best source of info on these things? I know about http://www.thedieselpage.com/, but I figure there are others.

    Main things I'm interested are:

    1) Small tweaks to help performance (although 300/520 is nothing to sneeze at). I'm thinking 4"+ exhaust and breather upgrade plus maybe a VA box? When I can afford it that is. /forums/images/icons/laugh.gif

    2) Auxilary fuel tank! What nitwit decided to put a 27 gal fuel tank on this thing? My Ram with 360 had a better range! Anyway, I want one to go under the chassis if possible. I'm thinking this thing will probably wind up with a camper shell on the back so filling a tank in the bed will be a pain. Although, a ~100 gal tank in the bed (top to bottom in the front) won't take up that much room, and I could probably mount a filler neck to the side of the shell...

    3) Any other tips, tricks, warnings for a (mostly) diesel illiterate newbie?
     
  2. BlueBlazer

    BlueBlazer 1/2 ton status

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    Id wait to put a fueling box on until these motors prove they can take the extra power. Ive heard worries about the Common Rail system running at pressures higher than what it was designed for and its possible the internals of these motors arent built for much more than the stock power rating. Just keep an eye out for people having trouble with their rigs with increased fueling, if you dont see many cases of things going wrong, then go for it, if you do, then you might want to reconsider it. The 4" exhaust is a good idea if you dont mind spending a lot of cash on it.
     
  3. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Thanks for the info. I've been reading a bit over at thedieselpage.com and it seems like some of them have been "fueling" the dmax for over a year (including drag racing) with no longevity problems. I have no intention of going for such things (drag racing) so I should be fine throwing the switch once in a while for towing. Probably wouldn't even run the max settings. My main concern is that I know nothing about all these "options". Large exhaust, "fueling", turbo tuning/modifications (waste gate and such), propane. What works? Best bang for the buck? What is dangerous? What order do things need to be addressed? (i.e. what mods need other mods to work right). That sort of thing. Also, what other websites have dmax/HD info? Sorry for the scramble, gotta rush, wife has dinner ready! /forums/images/icons/laugh.gif
     
  4. BlueBlazer

    BlueBlazer 1/2 ton status

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    If youre just towing then I would keep it simple. 4" exhaust maybe, some sort of aftermarket free flowing air filter, fueling box of your choice, and be very meticulous with maintenance like fuel and oil filter changes, etc. Im by no means an expert on the Dmax, but with a better exhaust, intake, and computer, you should be putting out more than enough power for your needs.
     
  5. MudNurI

    MudNurI 1/2 ton status

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    Congrats on the truck- What color is it?

    Okay- to answer some of the questions you have had. First off- the reason you have a smaller fuel tank, is because the general has offered the large tank in ONLY the long bed, There are a few people on TDP (diesel page) that have added bigger tanks, but since mine gets 20.5 mpg, I'm not worried about a bigger tank.

    Basically the ONLY place to get valid information is from TDP, John Kennedy is there- and ANY of the questions you have, he has answer's to. Bank's exhaust, Juice (edge) boxes, etc. He has a close relationship with the guy from Edge.

    There are quite a few (like TONS) of people over there that have the Edge box, and have had them for quite some time, most of them are very happy with it, and the bugs are being worked out.

    I'm not sure what your towing- but you really don't "need" anything other than the stock configuration to tow. This thing is a beast, to say the least.

    Some important things- make sure you change the oil, and rear end at 1,000 miles, it's probably going to run you about $300 if you have the dealer do it, but it's a good idea the first time to have them, so it's documented. Run only synthetic at that point, is more $$ but is worth it. Keep a spare fuel filter with you - our fuel filters are able to trap much smaller particles than other diesel filters, and when they go out, your in limp mode, and that sucks! I ran 22,000 miles on my filter, it went out, and then we realized, DUH its suppose to be changed at 15,000 miles.

    some people run fuel additives, if you buy your diesel from a high sales station, you won't have to worry about it. Here's some name to watch over at TDP

    Mackin
    john kennedy
    hoot
    nutnbutgmc
    and socaldmax

    those guys have tons of aftermarket options- and do the research we all should do.

    also- be careful with the allison with 33's on it, you may want to try to find a dealership to reprogram her, your shift points may be off, and if you tow with it, you may notice the allison not preforming where you want it. Some dealerships will do it, others wont.

    Also- watch your hydrobooster, for leaks that is, when it starts leaking, it will clean the frame, and that isn't cool! The waxy coating that the general puts on it will come right off. TRUST me on this one!

    congrats, and I hope you like your's as much as I like ours! 30,000 miles in 6 months YEHA!

    Brandy
     
  6. BlueBlazer

    BlueBlazer 1/2 ton status

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    Sounds like quite a few problems for only 30,000 miles.
     
  7. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Thanks, great info!

    It's a loaded white crew cab LT 4x4 and all the stickers removed. Well, almost all, I liked the top pinstripe so I left it for now. Hmm, I should put some pics up on my site. 33s (actually 285/75R16 ATs) are mounted on the stock forged aluminum wheels. I've already had it reprogrammed for the larger tires. 265s is the biggest that the computer can handle (or so they told me) and mine are 285s. That's only about 2 mph off at 75 so I didn't figure it would hurt. The service manager and the tech who did the adjustment said it would be no problem, we shall see I guess.

    So far my truck has only been getting around 15 on the highway, but I’ve been “enjoying” the power a bit after getting it broken in (first 500 miles was taking it more-or-less easy). Not as good as I had hopped, but I’ve read that it gets much better when fully broken in (after 5-10k?). As for power, this thing has more than sufficient power to tow my rig and trailer already. However, can a tow rig every have “enough” power? /forums/images/icons/wink.gif It’s like having a shop that’s too big, or too many tools. Just ain’t gonna happen eh? /forums/images/icons/laugh.gif

    On the maintenance, I’ve already got almost 3000 on it. Almost 500 driving around in N. AL and then across the US to Phoenix in only 24 hours without stopping for anything but fuel. I was planning to change the oil but hadn’t considered the rear end. IIRC, I now remember you posting about having some trouble or something with that rear end. Or maybe it was just the cost? I will get a fuel filter though, and I’ve got to spend some time looking at that maintenance schedule. There is so much on this thing that I don’t have experience with. I’ll also keep a watch on the booster…
     
  8. MudNurI

    MudNurI 1/2 ton status

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    Here's my list of problems with 30K on it- though MOST of these happened right at 22,000

    fuel filter crapped - caused Allison to enter Limp Mode, was the WORST 5 days of my life! truck wont shift, has no power etc.... this problem was caused by <font color="red"> me not changing the filter when it was suppose to be done, 7K miles late! </font color> <font color="blue"> and was in no way a fault of GM</font color> Hydroboost went out about the same time, <font color="red">this was GM's fault- and mines not the only one! </font color> <font color="blue"> again the reason I mentioned it </font color>
    Steering shaft has a nasty rattle- <font color="red">95 % of these have it!!!!!! </font color> <font color="blue">new TSB just released July 8th corrects the problem </font color>
    Emblem came off grill- <font color="red"> more than likely was the high end power washer I used! </font color> Rear Seat Belts needed to be replaced, locked without warning/moving etc. <font color="red">GM's Fault on this one! </font color> <font color="blue"> tech kept saying they worked correctly- however since they were replaced, NOTHING has gone wrong with them?? </font color>

    That's it, now that may sound like A LOT, but I think the fuel filter, which caused the Alli to go to sleep was caused by some fuel we ran,, and the fact we didn't change it at the correct time

    Might sound like a lot of stuff- but this truck is also a BRAND new engine, and a BRAND new transmission with GM, there are some bugs, and I'll give them time to fix them. All in All, this truck kicks a**!

    Brandy
     
  9. MudNurI

    MudNurI 1/2 ton status

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    Sounds like you got one that didn't come with the MPG option!! that's a big joke round the TDP...some of us get exceptional mileage, others get crap! We averaged about 17 for the first few tanks, now are up in the low 20's depending on whose driving!

    I posted before about the $$ of the service--- and the fact that they smushed/crashed my o-ring! drained 8 of the 10 quarts of oil- BIG NOTE- most lube center's -you know the ones the 15 minute change <font color="blue"> ONLY PUT 8 QUARTS IN........THIS ENGINE HOLDS 10!!!! </font color> there must be 10 guys at TDP that have had this happen! The computer at these places tells them 8 quarts, so thats what they put in...carefull with this!

    The tech was correct- 265's are as big as the allison can handle at stock settings....they can go up to 35's with no problem. local dealer has a 4" lift with 35's on the owners truck...and was reprogramed fine.

    glad to hear your trucks NOT pewter- seems EVERYONE has that darn color- ME included! haven't seen a white crew cab round here....We removed our Z-71 stickers on the 99 - with the powerwasher- the same one that took the emblem off my grill on the D/A !! Careful with highpressure, sometimes I think the paint will fly right off!

    Brandy
     
  10. arveetek

    arveetek 1/2 ton status

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    The Diesel Page is THE SOURCE for GM diesel enthusiasts. There are other places, like gm-diesel.com, but they all pale in comparison to TDP. Most of the other forums have very few members.

    Casey
     
  11. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    </font><blockquote><font class="small">In reply to:</font><hr />
    The tech was correct- 265's are as big as the allison can handle at stock settings....they can go up to 35's with no problem. local dealer has a 4" lift with 35's on the owners truck...and was reprogramed fine.

    [/ QUOTE ]
    Hmmm, your saying that 265s are the the most at "stock settings" but it can "go up to 35s". Does that mean it can be reprogrammed for my 285s with some other mods? Or just that it can mechanically (and electronically) handle the 285s while programmed for 265s?

    </font><blockquote><font class="small">In reply to:</font><hr />
    Sounds like you got one that didn't come with the MPG option!! that's a big joke round the TDP...some of us get exceptional mileage, others get crap!

    [/ QUOTE ]
    Hmmm, any clues on what the cause might be? Based on your wording I'm guessing "no".

    Also, the rear axle is not on the maintenance schedule other than to check, and I've never chained axle oil on a new truck that early. Just curious but, why?

    Thanks for the 8 vs. 10 tip on the oil. I’ll probably do it myself although, as you suggested, it might be better to let the dealer do the first one so I can prove it. But $300 is allot of $$$.
     
  12. MudNurI

    MudNurI 1/2 ton status

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    What I meant was that 265's can be run with no programing of the Allison to change shift points, the biggest I have seen with a REPROGRAMED allison is a 35....if your running 285's your's can and should be reprogramed, BUT some guys at TDP don't because this way, they get a "longer" warranty, since the speedo etc. is off? I won't run bigger than 265's so I'm not too worried about that, with the fact that in another 6-7 weeks, my warranty will be turned into the "$100 deductible warranty"..... pretty close to 36K now.

    I don't have a clue about the MPG, most people that are lower than others are increasing as the miles are put on, others like me, have always had good mileage....the saga continues, nobody knows for sure.

    I was told by my dealer that the rear end had to be changed, which is why we did it, I also after that fact read at TDP that everyone does it. Why, I'm not sure?? I thought it was a required maitence scheduled thing, kind of like some manufacters recommend/require a dealer do the first oil change? I don't know but TDP may know.

    All I know is I can't believe this is a "truck"....feels like the STS we had a few years ago!

    Brandy
     
  13. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Hmmm, it seems we have a miscommunication somewhere. As I said before, I *have* had the truck reprogrammed for the larger tires which are 285s. The tech (and service mgr) both told me the largest tire size that could be programmed in was a 265. So, they told the computer (as I understand it) that it was wearing 265s and I'm living with the speedo difference. From what they said, the computer will not allow them to enter a larger value.

    Looks like I’ll have to pony up the funds to join yet another site (tdp).

    I agree about the trucks performance and potential. All I can say is “WOW”! The Allison’s shifts still feel a little funny on part throttle acceleration but I’m told it just takes some getting used to. I’ll also try to check with a local dealer here in Phoenix (if I can find a decent one) about the rear diff oil change (along with engine). I wish I had thought to change the oil before leaving AL coming to AZ.

    Anyway, thanks for all the advise everyone!!! /forums/images/icons/laugh.gif
     
  14. kickinasphalt383

    kickinasphalt383 1/2 ton status

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    Congratulations on the new truck!

    Also I have always heard and been told to change the diff fluid early the first time on a new vehicle. We have done it on all our new trucks.
     
  15. MudNurI

    MudNurI 1/2 ton status

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    What I know is that the 265's and the Allison straight from the factory are dead on- along with the speedo- now it came with 245's so it must be off by a mph or 2, BUT I also know that a dealership in Keene, NH (GMC) dealership HAS reprogrammed the allison AND the speedo to fit the 35's and the speedo and allison are dead on. That's what I was trying to "say" ......

    Brandy
     
  16. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Hmm, thanks, that's what I was hoping you were saying, but it didn't mesh with what I thought I understood. Got a number and a name that I can contact? I would love to have mine set correctly for the 285s. Now you've got me wondering if the "tech" knew what he was talking about when he said the computer would only allow a maximum size of 265 to be entered. Thanks much for all your help and info...

    Also, anyone know a GOOD diesel savy and capable dealer/shop in the Phoenix area?

    BTW, I just signed up at TDP.
     

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