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Silverado / Sierra 2500HD Duramax ... any thoughts?

k2riderk2rider Posts: 21
edited March 2014 in Chevrolet
This is one of the two trucks I'm thinking about getting. It will either be the 2500HD Duramax diesel w/ the Allison transmission or the Ford F250 Super Duty. I trust the Ford more but like the looks (both interior & exterior) of the GMC product. I will get the 4x4, Crew Cab model.

I had a 1986 Chevy S-10 Blazer and it was a slug and maintenance was out of line. I haven't had a GM product since. I have a F150 Supercrew now but need more power for pulling our boat. I recently got a whopping 7.5 MPG on a trip from San Diego to Lake Powell.


  • cowboyjohn1cowboyjohn1 Posts: 125
    7.5 mpg pulling a boat? That is WONDERFUL! My 1988 F250 gets 7.3 pulling nothing but a few odds and ends in the back. I have gotten as high as 8 mpg-and this pickup is a real slug. You need to plan ahead when you are about to pass someone. On the other hand, my 2001 2500HD with 8.1/allison gets 10 around town and 13.5 on the road and it has loads of power. I am very happy with it. cowboyjohn
  • richcolorichcolo Posts: 81
    I have a 2002 GMC 2500HD and so far it's great. Mine is a 2WD Crew Cab with Duramax and 6 speed manual. I get 21 MPG commuting and 15 MPG pulling a 25ft 5th wheel. It has all the power I can use (even climbing I-70 west of Denver with the camper on tow...65 MPH and power to spare).

    I'd recommend you research the two trucks you mention at (for the ford) and (for the gm). I did, and both sites contain loads of good information in the forums.
  • Our fleet of Duramax 6.6's with the Allison transmission have been the best investment our firm has made in vehicles in years! So far, great performance, great dependability and the crews tell me they like the way they handle, climb hills, descend hills and the fuel economy. The only modifications we have made are:1.when due for replacement we have increased the tire size from LT245-75-R16 E to LT 265-75-R16 E. 2. Replaced the stock exhaust systems with a stainlees steel five inch (OD) exhaust system. We are planning to replace the other half of the fleet in our new fiscal year and we have already decided NOT to go to bid. We will negotiate with our local Chevy dealers and take the best deal offered.
  • texaszachtexaszach Posts: 119
    The last two Powerstrokes I bought were each brand new, a 1997 F250 Crew Cab short bed 4x4 (last year of the old body style)and a 1999 F250 Crew Cab short bed 4x4. The 97 developed a chronic water pump leak with less than 10K on the odometer. The 99 began leaking oil at the rear main seal just under 3k. The heavy duty truck division of my dealers service department said the engine would have to be pulled to replace the rear main seal. Though I hated to live with the leak, I decided it was better than having the engine pulled. Right or wrong it was my decision to make. I now own an F150 SuperCrew 4x4 but must admit that I am both intrigued and drawn to the lifted skirt and perfumed inner thigh of the Duramax diesel and Allison transmission. I have followed this engine since it was first announced that Isuzu would be developing the engine for GM. Several of my customers own this combination and all seem to be very happy with their trucks. I miss driving a diesel and think I'm going to give the GMC a try on my next purchase. GM needs to put this same combination in the new Hummer H2.
  • mdecampsmdecamps Posts: 115
    I would like a little bit of info on your truck. I'm thinking about purchasing the Duramax w/the 6 speed manual. None of the local dealers stock the manual and I was wondering how it drives. Is the clutch overly stiff or easy to push down? Is your 21MPG in the city or on the highway? Thanks for the info.

  • I purchased my 2500HD,2002 in Jan.. At 1500 miles I was getting 20 mpg, at 75 mph, once it breaks in they say I will get more. I talked to one guy who advised me he was getting 24 mpg.
    This is the best truck I have ever owned! The factory tires and rims were a bit too small so I purchased 8 inch rims and LT285-75-R16. The ride and look is much better!
  • pallypally Posts: 17
    I am a Air Condition serviceman in Houston and I have talked to a few guys running service out of the DURAMAX.
    The main issue with these trucks is the Allison 5 speed auto.
    It's not that they break, it's that for some strange reason they will downshift for no reason at cruising speed, redlining the motor, and scaring the HELL out of the driver. I have heard this from several people.
    And of course the dealer can NEVER duplicate the problem so you have got to live with it.
    By the way, every guy i talked to is getting about 15 to 16 MPG overall. Same as a Powerstroke.
  • jaijayjaijay Posts: 162
    GM has an update for the Allison that corrects the 4 / 5 shifty business. Check out for service information on this.
  • My husband has wanted this truck since he read about it in popular science. I didn't want to spend the $ but since we purchased it - We both love it. My husband tends to have a lead foot so I thought this diesel would slow him down - how wrong I am. He can easily burn rubber with an empty bed.

    This truck is used for flooring installation business so it is always carrying or towing lots of weight. It is one great work horse.

    We got the leather, power heated seats & they are worth every extra dollar we paid. This truck rides & drives so nice, I enjoy it more than my own vehicle. The engine is very quiet compared to the Ford diesel motor.

    This truck is rated a 10 in my book.
  • drmatt1drmatt1 Posts: 1
    Someone gave a website of I could not find the website. Please correct the address. I have been a happy 1993 Z71 w/locking diff owner and I am getting ready to buy a 2002 GMC w/duramax and I would like some info. Thanks
  • akjbmwakjbmw Posts: 231
    Go to or and search for dieselpage. No "thedieselpage" but other links were listed.
  • robo1robo1 Posts: 1
    I go to it all the time and find it very informative, try:

    In fact the diesel page convinced me to go ahead and buy my 2002 Duramax. Good Luck!
  • k2riderk2rider Posts: 21
    I've started looking at this truck and see sticker prices of $44-45K. When I run the #'s on Edmunds, *Invoice* seems to be around $39K. That's quite a hefty mark-up. Am I looney to go in and say "I'll give you X amount over invoice?"

    Anybody mind telling me what amount over invoice you paid/ Thansk for any help you can provide.
  • tapper99tapper99 Posts: 10
    You are not at all looney with this request. My dealer told me he would order me anything at $100 over invoice. Basically he said the 100 would cover clean-up and prep. Timing might be important on this-I ordered as soon as GM would accept new orders.
  • Saw on a posting by (pwrstrkthis) that he upgraded
    his rims from 6.5 to 8.0 to accomodate the larger
    285/75-16 tires. I am curious as to the make rim
    bought and the backspacing to maintain adequate
    clearance. Any info and problems incurred would be
    appreciated. Also, feedback from anyone who went
    to 265/75-16 tires would shed light on my decision
    of which tires to go with.
  • rayt2rayt2 Posts: 1,208
    Just keep in mind adding bigger tires reduces your final drive gear ratio, with the duramax behind it it may not matter but be advised. The computer can be reprogrammed to adjust for up to 2 sizes bigger than stock but that's the dealer limitation, there is an aftermarket device (can't remember the name)that you install and make your own adjustment but dealers don't take kindly to it should you bring it in for service under warranty and they see this, it will void your warranty.

    Ray T.
  • I installed American racing 16x8 tailgunner steel wheels and 285 75R16 tires. The only contact point was the plastic fender housing at the left front during a turn. I installed GM mud flaps also. Since it was plastic, I carefully and lightly heated the contact area with a propane torch and inserted a spacer (anything large enough will work) between the tire and the contact area until it cooled in a position farther from the tire. It worked fine.
    Checked GPS speed and the speedo is now 2 mph less than actual. 245's showed 2 mph more than actual.
  • For markntime. I installed the LT 265-75R16E tires on my 3500 with no adverse affects. The dealer service rep told me that any change of 10% (or less) in tire diameter doesn't require reprogramming. I have a more positive feeling with handling now. I don't know why GM didn't just offer this tire size as an option.
  • Just got the 2003 K2500HD Crew Cab 4x4 with the DuraMax and Allison. Very nice ride compared to my 1999 C2500 Crew Cab with the 454, not to mention at least twice the gas mileage! After my 2nd tank I'm getting 19mpg in a very hilly town. Only small complaint is the sometimes hard shift from 1st - 2nd (especially when cold) and even rarer hard shift from 4th to 5th. Allison and GM say its normal due to the Heavy Duty design. I swore against diesels forever, now I don't know if I'll ever go back to gas for a HD truck. I'm told the hot setup is the Duramax with the Duramaximaizer for about $795 installed you get 400hp and 650 lbs torque, spinning back wheels in 3rd and can out run the Mustang in the 1/4 mile. ( You can even turn it off to fool the factory service computers to thinking its not there (i.e. no warranty problems). If you need a big truck that can pull a lot, there is no need to look further!
  • paisanpaisan Posts: 21,181
    What is the 4x4crew cabs looking at as far as pricing? I'm considering replacing my Trooper with another Isuzu engined vehicle and like the idea of Diesel. Thanks for any info you guys can provide.

  • I have the 8.1 with the Allison and I have smooth shifts in all gears. The only time it has yanked me around is slowing for a stop light, not quite getting stopped, and then punching it to accelerate. This occurs when the transmission is shifting down thru third to second, and then hitting the power just as it is getting ready to shift in first. Hitting the power causes it to go into first and that will jerk you a bit. Other than that it has been perfect. Very happy with it.
  • I have an 02 2500HD with the 8000 and Allison Trans which I am extremely happy with. Replaced a 460 Ford and get much better ride and handling empty and pulls 10,000 trailer with ease. The allison takes getting used to, but I wouldn't want anything else now. With 8000 miles, getting 11 MPG in town and averaged 9.8 MPG pulling the trailer.Question? Anyone purchased a GM extended warranty and were you able to nogotiate the purchase price by checking several dealers?
  • n75v111n75v111 Posts: 243
    Was just thinking about you the other day was wondering if you still visited this site.

    My Allison 'HAD' what I refered to as a 'SLAM SHIFT' between 2 to 1 with your described Slow Down/Go Around situation. Been pushing GM for extended warrenty which just received 8/02. 5yr/100,000 on the Allison. There is a GM SB 02-07-30-020 called Harsh or Delayed Shift 2-1 issued March this year on reprograming and so far it has ellinated the problem. Have 22K now - Pulls a 32' Excel 5th whl like a dream though.

    Hows the Airways treatin you??

    Loren (N1575V)
  • Loren - I sure appreciate the information. I will be asking the local dealer about that and will show him your note. I guess I didn't think much about it, but when you said it can be fixed, I am going to pursue that. Lately, my remote door opener/lock has not been functioning well. Sometimes I can be right beside it and it will not open. Last night it opened from about 30 yards, so I don't know what to think. I replaced the battery, but didn't seem to help. Been thinking about taking it to the dealer, but want to get winter preparation out of the way first.
    On the flying bit - my airplane sprung a leak in the right wing. $3500 and about 3 months later it was fixed which consumed all summer. Got it back Sept. 1st, but haven't even flew it yet. Been painting a house and some outbuildings - hadn't been painted since 1966 - so they needed significant work which took lots of time. Still need to get 8 sprinkler systems blown out, pumps shutdown and drained, and last cutting of hay up which I will cut today. Probably won't get dry, but I will bale it anyway and feed it first. Result - no flying for at least 3 to 4 weeks. Hope you had a good summer, and hope your Silverado treats you well.
    Cowboyjohn - N7137L
  • n75v111n75v111 Posts: 243
    Maybe we should talk and I can fill you in on what I had to go thru to get the 5yr/100k Allison warrenty. Wk 641-754-3401

  • I am thinking about ordering a 2500hd d-max 4x4 ext. cab. I am debating over Manual v. Auto Trans. My debate centers around my wife however, as she doesn't drive manual, and frankly is too stubborn to learn. Does the manual have power take off, is it an option? The power take off may be enough to convince here that it really isn't that difficult. I have only driven cars with manual. Is there a significant difference with an engine of this size. Any information would be greatly appreciated!

  • Power Take Off (PTO) has nothing to do with driving the truck. A PTO option is a provision in the tranny for connection to an auxiliary device, such as a hydraulic unit to power a dump bed.

    I have to admit something, I cruised over here to see how badly you GM guys were bashing the Ford's. Not even so much as a jab.
  • phkckphkck Posts: 185
    My dad had not started his Silverado with Allison Transmission and diesel for 6 - 8 weeks. Had to call AAA to get it started. When finally running, the truck would not go more than a few feet. Shut it off and left it for awhile. Went back, started it up and no problems, drove fine.
    I know little about this set-up, any thoughts?
    I imagine letting any vehicle sit for 2 months may have problems starting. He does have a cab over camper that may have had some parisitic drain of power. Also, factory security system was on the entire time.
    Thanks, Paul
  • Maybe try one or more of those solar cell chargers to keep battery fresh. Or a plug in maintainer. That's a long time to sit in winter.
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