Gentlemen, we own two Duramax/Allison vehicles, one a 2001 3500 CCab and a 2003 4500. They are used (not abused) for mobile fleet repair. Everything goes well until 40,000 on the 01 and 31,000 on the 03. Then into the shop they go, for three weeks at a time, fuel injectors, leakng fuel lines, no power. It is true that the fuel pressure is up at 27,000 psi.and when the supply and return lines leak internally the engine oil goes external. Isuzu (yes Isuzu and not GM dictates the repairs) will only replace injector(s) that are bad, one at a time, or two or three or four as we have had. The 4500 was smoking so bad that you could not see the truck from 20ft away and I am serious. They replaced all four injectors on the left bank, pressure tested the right bank (as per Isuzu's instruction)and called it good. The truck made it 150 miles and would not go over 30 mph. Towed back to the dealer (who in all fairness is the best one we have
found so far) where the other four were replaced. The 01 is on its second complete set of injectors. Much is made about the quality of fuel, but I have to question why sell a product that cannot use the fuel that is available? Another interesting feature of the Duramax is what GM refers to as "Phantom Idle". Drive along at freeway speeds and without warning the engine rpm drops immediately to idle, no throttle response whatsoever ( the TPS is the throttle pedal, drive by wire) you can (if you don't get run over by the semi behind you) pull over, cycle the ignition several times and it MAY be okay, if not tow to your local dealer, where no logged faults can be found in the engine management computer. The standard reply is always "if it happens when we have it hooked up we could see it" followed by "yes, we know it is a problem". Now for the really interesting part,the GM dealers were really concerned that they were going to get audited by GM for excessive percentages of warranty claims regarding the Duramax until they compared notes with other dealers and found that ALL the dealers that perform warranty on Duramax are in the same situation. If anybody out there thinks this is untrue the dealer that we take our vehicles to performs the same warranty related fuel problems on 10-12 Duramax powered vehicles per day. Even the salesmen do not push Duramax powered units because of all the problems. As for the new 04 engines, the only difference is that the injector position has been changed to make them more accessible, the injectors themselves have not been changed. Do all of you out there realize that a set (8) of injectors installed is $5000? We have existing case numbers with GM for both vehicles and have had long conversations with people both inside and outside GM. The bottom line is that they know there is a problem and they quitely acknowledge that they have no "fix" in sight. The upgraded fuel filter is a "patch" not a cure. Isuzu is pointing the finger at Bosch saying they don't know how to build injectors and Bosch is replying that Isuzu does not know how to design injectors (Bosch manufactures to Isuzu specifications). GM does not know what to do. Ask yourselves this: If there is no problem with the fuel system, why undergo a major redesign after only three years? GM's quoted life expectancy for this engine is 500,000 miles. They admit that it is going to be nowhere near that. After 68,000 miles on the 01 the oil pressure is down by 12psi. Now, take the $7000 premium you pay up front, add $5000 for each 30,000 miles above the warranty 100,000 miles and I will be generous and give the engine a life of 250,000 miles. Thats $31,000. New replacement cost for an engine (complete) is around $15,000. Thats $46,000. You are now in CAT, Cummins territory and you will get 1,000,000 miles out of those units. If any of you think about using the lemon law, don't bother, it does not go above 9,999 lbs GVW and GM is fully aware of that. Sorry to be so long winded, but it really is time for Duramax owners to learn what the real problems
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