Silverado/Sierra Duramax Diesel Problems & Solutions

jgmilbergjgmilberg Member Posts: 872
edited March 2014 in Chevrolet
A friend of mine has purchased a new '04 Silverado 2500 HD Duramax Diesel Crew Cab. He previously owned a '01 Siearra 2500 Duramax Ext. Cab, and traded it in for the larger cab. The problem is the the fuel economy, in the '01 he would get around 23-27 MPG and now his new one is only getting 10-13 MPG and horrible towing mileage of 5-7 MPG. This truck also lacks the grunt the old one did, not a lot of power when passing on the highway. It has been back to the dealer 3 times and they claim all is well, the computer is not showing any problems and the programming is up to date. A check of the engine oil at the first oil change showed fuel in the oil and the dealer still says it's normal. Has anyone else out there had these problem and if so what was the fix? What should he be looking for as far as power and milage and performance out of the '04 model vs. the '01.


  • quadrunner501quadrunner501 Member Posts: 94
    1.) The 01's never got 23-27 mpg. I own the '01, 23 mpg with a tailwind maybe, 19-21 being realistic and taking it easy.

    2.) '01 Duramax rated 300hp 520ft/lbs, '04 LLY Duramax rated 310hp, 590ft/lbs.

    3.) The '01 Duramax has the fuel injectors located under the valve covers, so if one leaks, you can get diesel fuel mixed into the crankcase oil. The '04 LLY has new heads, the injectors have been located OUTSIDE the valve covers so if one leaks, diesel fuel runs down the outside of the engine instead of inside where it could mix with the oil.

    4.) No legitimate dealer will say that fuel in the oil is normal. There is a service bulletin that outlines a method for determining if fuel is in the oil, and if it is, further recommendations for checking injector balance and replacement.

    5.) Power and mileage of the '04 and '01 should be roughly similar, with perhaps a slight edge going to the less powerful '01.
  • jgmilbergjgmilberg Member Posts: 872
    Talked to my friend again and he said that he never got any less that 20 MPG with his '01, his '04 is only getting 10-13 MPG. When towing with his '01 he would get around 16-18 MPG, the '04 is only getting 5-7 MPG towing the same trailer with the same load. The oil did had fuel in it. The PCM has the latest calibration, and shows no trouble codes at all. He tried a few other dealers and 2 of them told him flat out that they do not have a diesel tech, the other, again said there is no problem that they can find. Another guy at work said they had the same problem and the same type of problem with fuel economy and poor power on his '03 his problem ended up being one or more liners. The dealer wouldn't even discuss this issue at all.
  • quadrunner501quadrunner501 Member Posts: 94
    Okay, I see your point now. It's a problem without a solution. Thanks for sharing those 2nd-hand experiences from your friends.
  • jgmilbergjgmilberg Member Posts: 872
    I posted here to find out if anyone else was having this problem and to see if they were able to get it fixed, not to have someone ridicule me for posting for a friend! If my friend had a computer he would do it himself. If you don't have any idea about what could cause the problem or possible fixes for it please refrain from posting. You said there was a TSB about the fuel in the oil do you have that TSB number? This is a new design for '04 and there could be bugs that need to get worked out, so if there is anyone out there with ideas on what to check please post them.
  • youngeryounger Member Posts: 16
    Hey all. Questions for you. I bought a 2004 2500HD with DMax and Allison about a month ago. All was going well until early last week when I noticed the tranny leaking fuel. so I took it in. dealer said is was an O ring the was shot, that was replaced. Well yesterday (a week later) same thing but much worse. GM engineers have been made aware of this problem, however from what I've been told, don't have a fix. Anybody hear of this? IF so, do you guys know of a fix? I'm absolutely heart broken thinking my truck is cooked here!

  • youngeryounger Member Posts: 16
    I got the truck back and this is what I was told by the dealer. The bell housing on the tranny contained a groove where it would bolt on to the the engine block, actually part of the initial design. Since there are some problems being reported with leaking, the initial fix was a simple washer. However that wasn't working, so a new bell housing was put on without the groove. GM claims this is the fix, and that was coming from the engineers, so we'll see.
  • youngeryounger Member Posts: 16
    Well that wasn't the fix either. Two days later the leak continued. As I went deeper up the GM creditial list, I was told that I was one the few trucks with the problem, for now. So myself and my truck got to be the "test". What they finally fixed was the transmission pump. Apparently there was some pitting on the actually casting (poor cast), thus allowing the fluid to seap through. So this is where we are at. This was attempt 3, and if there is a 4th, the old Lemon Law will be kicking in.
  • chrisg3chrisg3 Member Posts: 1
    My 2003 Duramax has had some problems over the last six months. Mainly, it has been in and out of the shop because it won't start 80% of the time. I have to manually prime the fuel before it will start. Every time I pick it up from the dealer they say they have fixed it, which pans out to be untrue since I find myself, once again, priming the fuel manually. It is now in the shop again, for the 5th time. Unfortunately, I'm in my second year of ownership so the Lemon Law doesn't apply (to my knowledge). Has anyone else had this problem? What was the solution?
  • youngeryounger Member Posts: 16
    I'm not sure what state you live in, however this is my interpretation of Wisconsin's Lemon Law.

    1. Problem has to originate within the first year of purchase
    2. Problem has been attempted to be fixed 4 times within the life of the warranty
    3. Loss of usage of the vehicle for greater than 30 days.

    I hope this helps.
  • rayt2rayt2 Member Posts: 1,208
    Gives you 18 months or 18k miles for the same problem 3x back or more.
    Been there done that.......

    Ray T
  • jaijayjaijay Member Posts: 162
    When was the fuel filter changed and by who. In many cases where the fuel filter is not installed properly the fuel system will lose prime.
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