Duramax LB7 Smokes at idle

OK all you Duramax experts, I've already received one opinion from a friend so I need a couple more before taking BART to a shop. At idle, I'm getting a pretty excessive amount of exhaust smoke. It's blue in color and smells pretty rich. The idle is smooth and there seems to be no loss of power or mpg and performs well as always. Lin has been behind me in the car and hasn't noticed any excess smoke or diesel smell.

Ideas?? I've recently added Diesel Kleen.

Ray, "blue smoke" most of the time means its over fueling. Could be an injector or a few other things. Maybe a small piece of carbon is sticking an injector open a little. Is the LBZ a "1" or "2" engine. A "2" engine is a 04 and a 1/2 and same as used in a 05. The "1" is the early design. Different injector design. Take it on a "bonzi" run for a few miles and see if it clears up.

Ray, if you are having blue smoke at idle and startup I would lean more towards valve stem seals but if the smoke is always during idle then it's an injector.

Bob&Patty said:

Ray, "blue smoke" most of the time means its over fueling. Could be an injector or a few other things. Maybe a small piece of carbon is sticking an injector open a little. Is the LBZ a "1" or "2" engine. A "2" engine is a 04 and a 1/2 and same as used in a 05. The "1" is the early design. Different injector design. Take it on a "bonzi" run for a few miles and see if it clears up.

Click to expand...

In 2005 when they switched to the LLY engine, it was changed to a "common rail" injection system.

When I had the GMC with the LB7 I remember that it was an injector problem. Good luck!

Ray, I had a 2002 GMC 2500HD with the Duramax and I had problems with the injectors that caused excessive smoking at idle. This is a known problem with the LB7 and GM extended the warranty on these injectors to 7 yrs/200,000 miles. I started having problems at around 96,000 miles and after a couple of trips to the dealer and trying a couple of different additives they finally relented and replaced all 8 injectors at about 123,000 miles. Problem solved; for a while. The "new, improved" injectors didn't last as long as the originals. I started getting the smoking again at around 195,000 miles. When I went back to the dealer they tried to tell me the warranty on the replacements was only 36,000 miles and I said, "Your kidding me, right?" After I, personally made several calls to GM they finally agreed to replace the 4 on the left bank (that seemed to be causing the problem) because I reported the problem before the original 200,000 mile warranty had expired. By the time I sold the truck with 219,000 miles on it, it was starting to smoke at idle again. I suspect the 4 on the right side were going out. Since you have an '04 model I would suggest you hurry on down to your dealer and see if you can get in under the 7 yr warranty limit. Good luck.

Thanks for all the replies. The original injectors were replaced about 2-1/2 years ago at 80,000 miles. I now have just over 112,000. I guess a trip to the Chevy dealer is in order. I have all the previous paperwork but it's all in their computer too so I may not need it. I'll report the outcome when I know. Thanks Again!

Ray LeTourneau said:

...Ideas?? I've recently added Diesel Kleen.

Click to expand...

Did it smoke before the Diesel Kleen?

John

newbie said:

Did it smoke before the Diesel Kleen?

John

Click to expand...

Actually I added the DK when we arrived in Charleston. It seemed to stop smoking for a while. When we left for FL, I used up the tank with the DK in it and refilled without the DK. The smoking came back. I really don't know that the DK had any effect because I really didn't drive the truck much in Charleston. It may have never gotten fully warmed up.
I think it's probably best that I take it to a GM dealer with a Duramax tech. They have all the history and are probably better equipped to git er dun.
But to answer your question, yes. It smoked before the DK.

Hi guys. I just wanted to tell you my experiences with these diesels. My truck has been an fifth wheel tower it's whole life and has 350,000k on it now. The injectors were just done 40'000k ago. I knew it wasn't under the special warranty but I brought it to my dealer anyways when I started having blue smoke out the exhaust. The injectors were just done for the last time under the special policy and I was worried they were on their way out again. I have a friend that works at the dealer I deal with and ihe is a very skilled mechanic. He is the shop forman for that dealer. I showed him the trucks exhaust while running and he said it had nothing to do with bad injectors. This guy has been to an actual duramax diesel training course so I took his word for it and I'm glad I did. I'm not gonna gaurentee that this will work for everyone. All I can say is it worked for me. My friend told me that next time I changed the fuel filter to fill it up with seafoam. This way the seafoam hit the injectors in it's pure form and cleans them quickly. He said that the newly revised injector design will last far longer then the previous designs if they're taken care of properly. He was the one who replaced the injectors last time for me under warranty and I asked him if he could make sure the new disigned injectors were put in. He sayed that the new design were put into my truck. He sayed to me that the only problem he's had with the newest injector design is when run for long time without cleaning they get gummed up and stick open. Once this happens they need to be replaced so keeping them clean is vital for their performance and longevity. So I do work that is not covered by warranty to my truck so I took the filter out replaced with a new one and filled it with seafoam. Went for a nice long drive and within an hour the blue smoke was gone completely. So I went back to the dealer and told him it worked really well. He told me that when the injector nozzles get dirty their injection timing goes out which cause the blue smoke. He says that when they're dirty they inject slow and longer then normal and when they're clean the inject fast and shorter which is the proper timeing thing. He tells me that that product seafoam in it's pure form liquifies carbon deposits cleaning the injectors completely. Now he recommends me to run a tank of fuel with 2 cans of pure seafoam in it every few months for proper injector maintenance. He sayed the fuel filter full of seafoam method is to be used in worst case senarios when the timing of the injectors is actually producing incomplete combustion. Now it's been 4 weeks and I've never seen one bit of blue smoke I'm gonna stick with this method of injector cleaning and hope my injectors last longer then I own the truck. I also always run fuel that is mixed 5% biodiesel. It's supposed to be the best lubrication for the injectors.

What you did by filling the filter many dealers do with high tech power injector cleaning machines.

Well I guess my auto save feature isn't working. I typed a reply detailing the last dealings with the truck and lost it. I navigated away from the page without hitting submit.
Anyway, we had the high pressure injector cleaning performed in Port Richey. It didn't work as we hoped it would. A balance test of the injectors was good. The tech then thought it may be related to the turbo but needed to keep the truck to do more diagnosis. It was nearing time to head north so I declined.
We towed Lin's Sebring home and used Howe's injector cleaner in all fill ups. Double dosed per instructions. Still smoking more than it should so I guess I'll be taking it to our local dealer. By the way, mpg while towing Lin's car, 18 mpg. So there is no lack in performance at all.

I took BART over to THIS PLACE yesterday. I stood there as the tech hooked up the scan gauge to check the injector balance. It appears the Chevy dealer in FL was re-routing some of that blue smoke to my posterior section. I have 2 injectors out of spec (one on each bank). The tech was very helpful in explaining everything in detail and showed me some failed injectors, He didn't think I had cracked casings but rather a ball and seating issue. Bottom line is, BART goes in for all new injectors Monday at way less $$$ than the dealers price.
I found this shop on the Duramax forum and they area a contributer so my feeling is they will do a great job.

So Bart doesn't qualify for the extended injector coverage?

porthole said:

So Bart doesn't qualify for the extended injector coverage?

Click to expand...

Nope! Originals were replaced about 3 years ago by a GM dealer under the extended coverage. The replacements are only covered for a year. We're over the 7 year limit for the extended coverage anyway. In addition, I hear there are no "new" injectors available for the LB7. The way I hear it, there are so many cores out there the only thing available are re-manufactured units. I also hear we have to be wary of the company doing them.
All in all, it's a lot cheaper than a new truck I guess. I'm glad I like my truck.

I run the OPTI-LUBE in every fuel tank. It's a bit more than the Diesel Kleen, but it seems to work for my Duramax. I only use the truck to tow the 5vr, so she sits for 2 to 3 weeks before I start'er up on the weekends. In ref. to the Duramax Forum, it's a great place to get information & help. Just don't get discouraged by some of the posts on there. Some of those, are some young guns with 600+ HP and constantly breaking things. Great place for info. though.

Love them Chevys !

Sandpirate69 said:

I run the OPTI-LUBE in every fuel tank. It's a bit more than the Diesel Kleen, but it seems to work for my Duramax. I only use the truck to tow the 5vr, so she sits for 2 to 3 weeks before I start'er up on the weekends. In ref. to the Duramax Forum, it's a great place to get information & help. Just don't get discouraged by some of the posts on there. Some of those, are some young guns with 600+ HP and constantly breaking things. Great place for info. though.

Love them Chevys !

Click to expand...

I hear ya about "The Diesel Place" forum. Lots of good info but we have to be selective about what info we really need. This Lincoln Diesel Service has trucks they use in Competitive Pulling Competitions. But they also know their way around the Duramax for guys like us. I truly anticipate good results from them.

No more Smoke! I picked up BART from Lincoln Diesel yesterday. As expected, all is well. Time will tell but my experience with these guys has been enlightening to say the least. Brent takes the time to explain things and really seems to be thorough. They hooked up the scan tool to show me the difference between before and after. All 8 injectors were much closer in pressure. Almost no variance at all. The truck is quieter and smoother and the exhaust even sounds smoother if that makes any sense. Total cost, $3248.00. Their Website They are out of Wautoma, WI but have a shop in Plover which is where I had the work done.

Westcoaster,

Good afternoon. I have been experiencing the same issue on my 03 GMC Duramax, smoking at idle. I had the injectors replaced under warranty 50k miles ago. I told the local Diesel Mechanic about the Sea foam idea and he said Sure, couldnt hurt. I picked it up from the shop this AM and so far NO SMOKE. I hope it keeps working. Thanks for the post.
Paul B.
Pella, Iowa, USA