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inkram · 06-21-2018, 12:58 PM

I have a 2004 gmc Sierra 3500, with the Duramax, but I am not sure which version Duramax it is. Recently at an idle and stop and go traffic it is starting to smoke. The smoke is a blueish color and I noticed it has a slight oil burning smell. I have 145,000 miles on it. Does anybody know what it might be?? I am thinking bad injector but I hope not.
Thank you

Craig1960 · 06-21-2018, 01:25 PM

Sounds like an injector or more to me as well. They did have problems from around 2000-2006 I think was the range.

inkram · 06-21-2018, 01:26 PM

Yeah that's what I keep hearing

uncledon · 06-21-2018, 01:42 PM

I had to replace the injectors on my 2002 Dmax @ 110k. The shop put in the newer ones that are supposed to be better engineered and not inclined to stick open which I understand is the issue. I have 158k on the motor now and no issues.

When the 3 went bad I didn't have smoking issues that I recall, but I noticed a marked decrease in oil pressure due to fuel introduction into the oil via the bad injectors. Naturally I had all 8 replaced.

I have read where bad injectors will cause the symptoms you describe.

inkram · 06-21-2018, 01:51 PM

Thank you, for your help

2Yung2 Quit · 07-12-2018, 08:52 AM

Mine was smoking horribly. People were flagging me down assuming that I hadn't noticed the smoke. It was an intermittent problem. I couldn't make it happen for my mechanic. So I let him keep the truck for a couple days. After much trouble shooting and driving around he was able to diagnose the problem. It turned out to be a a loose connection in the exhaust. For emission reasons, the fuel system will inject diesel into the exhaust to cause a burnoff. The result of this burnoff was leaking out in the form of white smoke. He tightened the loose clamp, and I haven't had an issue since.

inkram · 07-12-2018, 10:19 PM

Yeah my mechanic said it could be a bad turbo. Seals might be leaking, so I went to Tennessee and half way there the turbo let go.

inkram · 07-12-2018, 10:20 PM

I'm exploring the idea of putting a supercharger on it instead of a turbo

FredV · 12-16-2018, 06:25 PM

The 8th digit in the vin code tells what engine is in the truck. If it's a 1 the injectors are the bad design, a 2 or D would indicate the engine has the redesigned injectors. Another indicator is the presense of rubber return lines and steel external high presure lines to the injectors.

engine103 · 12-16-2018, 08:03 PM

I have a 2004 Duramax 6.6 liter that had a very bad smoking problem whether idling or under way, there was smoke and lot's of it. It was the factory injectors that were causing the problem. Shop tested for bad injectors and replaced, problem solved and all was fine. Then about a year later, the other injectors that were not replaced started to fail. These were covered under a recall but like most of us we had passed the mileage and or time limit so were not eligible for the recall. The big problem with the 2004 6.6 is that the heads have to be removed to change out the injectors so you are looking at about a $2,500 / $3,000 repair job. If your going to replace, do them all at once. I'm now at 250,xxx miles and running great. Jim E. OKC

FredV · 12-17-2018, 06:06 PM

The cylinder heads do not need to be removed however both the upper and lower rocker covers need to be removed to replace the injectors. I replaced many sets of injectors on these trucks some multiple times while working at a GM dealer. It's sad that these engines had the injector leak issue since there were very few other problems compared to other manufacturers.