Just thought I would let yall know what I have seen and found on the new LML trucks. I have had 2 different customers come in complaining about smoke coming from under the hood when driving around town. I found that there is fuel on the out side of the exhaust pipe up by the down pipe. Best I could tell is when going into regen the fuel that is injected in to the down pipe is leaking out of where the 2 pipes come together. I have not confired the smoke concern however did find a doc ID #2531190. The doc talks about realigning the exhaust for a better fit. This is just fyi. Should be no problems with the truck other than the fuel leak. It only happens during regen so the mpg's should not change wheather you have the problem or not.

I just had this issued taken care of. and while my 2011 sierra 3500hd z71 was in the shop they let me take one of the another 3500hd out for the next couple days in till mine was fixed. After the truck regen the fuel the mpgs sufficiently drop from the normal 18mpgs to all the way down to close to 5. i would have to say this gas exhaust leakage / problem does effect your truck. i was told by the dealership that all of the new trucks have this problem so get them sent in to get fixed guys.

Thank, i hope to pick my 2011 up in nov, thanks again for the info

I had it happen today. It was after about 20 minutes @ 70 mph whenever i exited off of the highway and stopped smoke came through the vents and out of the hood. Crazy for a truck with 2400 miles on it

That just goes to show there is no quality control these days......seem like they rush too make a good product

Probably should have designed that 9th injector into the front pipe of the exhaust past the flange, NOT into the downpipe from the engine before the flange. Silly mistake, but could be costly down the road.

That just goes to show there is no quality control these days......seem like they rush too make a good product

No, shit happens.

Quality control: If there wasn't any every piece of these trucks would be falling apart.

i too have this problem.....my buddy almost bailed out of the pass side when he saw the smoke!! I think he though we were gunna explode LOL

I wonder what it would take for one of these to catch fire? With fuel leaking out on hot components.

Wow this is scary, diesel autoignites at 410*F. We may see some HOT trucks soon.

Maybe what's really happening is that when you blow by one of those Fords, they are getting sucked up in our air cleaners and stuck in the down pipe :D LOL
In all seriousness I have been thru one
re gen cycle and didn't have any problems.
I hope it stays that way. :)

is there a way to fix this problem ... some sort of kit? or will the dealer have TSB?

Took mine in to the dealer today. I gave them the doc id # that goodwrenchtech provided. They looked it up and let the truck cool down. Did the exhaust realingment and said i should be good to go. Will see if it works.

thats kind of odd must be something simple because ours does not do it. Let us know if it fixes yours!!! Good Luck!!!!

isnt the 9th injector injecting DEF and not diesel?

I don't have this problem yet.

Of course, I've only got 900 miles on my truck. Maybe it hasn't regen'd yet?

If there is that many trucks with the issue, dont yall think there'd be a recall?

isnt the 9th injector injecting DEF and not diesel?

No, DEF is constantly injected into the exhaust stream. The ninth injector is for DPF regens only.

i have this same problem . i have about 600 miles and it did it twice. had it to the dealer and they said they couldnt find anything the .exhaust pipe was a little wet with what looked like oil possibly from mfg there are no leaks from the joints. i wiped it off and lets see what happens.

Same smoke problem here. Took delivery of my truck 2 weeks ago. Mostly 'round-town driving. Love the truck. Awesome. But smokes! Dealer is going to take care of it. Should be fine.

I have 330 miles on my new Denali LML and noticed this today! Looks like I will have the dealer come and get it Monday so they can fix it for me.

Thanks for the Doc #!!!

I have 1800 miles on my turck and have yet to see smoke, is this an early build issue?

My dealers service dept. thinks every one the comes in with a complaint is an idiot with baseless claims. I took my truck to Gallagher GMC in new Britain,CT to have the smoking from underhood issue adressed. of course it only does it in regen and the truck was not regening when they looked at it. I provided the doc # and the tech told the service rep that "this doc is for an exhaust leak" "there is no exhaust leak on the truck" funny then maybe there is a microscopic indian under the hood sending smoke signals because if its not an exhaust leak that is causeing the smoke i dont know what else it can be.

update: truck doing its normal smoking from underhood AGAIN. This time with a bunch of people around all pointing (kinda embarassing when you have to explain to everyone why your brand new +$50,000 is smoking out of the hood) So I took it back to the dealer tried to explain to them that it only does it during regen. Im judging regen but the slightly elevated idle. He said is probably wasnt regen if I didnt get a message on the DIC and it should only regen every 2500 miles or so. After I explained to the service rep. what regen was she had a tech come out with a tech 2 and put it into regen manually to try and make it smoke....didnt happen i dunno what makes this thing smoke from under the hood and when! but it is still doing it on the pretty regular basis......

He said is probably wasnt regen if I didnt get a message on the DIC and it should only regen every 2500 miles or so. After I explained to the service rep. what regen was ...

You need to go to another dealer - seriously...

You need to go to another dealer - seriously...
Agreed!
The bulletin covers the issue with fuel leaking out of the exhaust pipe at the joint.
I would run from that dealer and find another.

looks like there are more lemons that gm is making....i really wanted a new one,,, not know..

looks like there are more lemons that gm is making....i really wanted a new one,,, not know..

I'm sure you did with a link like you have in your signature... :rolleyes:

That just goes to show there is no quality control these days......seem like they rush too make a good product

If it ain't broke there aren't enough features!! :D

Does this issue seem to be happening to GMC's more than Chevy's? I'm wondering if it's a manufacturing glitch at the GMC plant if that's the case?

Started smoking on mine now and i will add it does smell pretty bad. Had it for one week and 300 miles.

Well I just had mine fixed... The coolant tanks are coming overfilled from the factory! So once it heats up and is under pressure... about 20psi it is spewing coolant onto the exhaust manifold... That is the smell you are getting... a little bit of a sweet smell. Take it to the dealer and tell them to drain some coolant out of the system. Hell my dealer picked up my truck from my office, left me a loaner and dropped my truck back off when it was all done without even think twice since I had 400 miles on a brand new truck!

Mine just smoked today for the first time 700 miles

WOW! If the coolant tanks are overflowing, you would think that there would be an over flow hose that would direct the coolant away from the exhaust and onto the road? And once the system has purged the enough of the excess coolant, it shouldn't be an issue again? Sounds like it could be two or more different things causing the smoking.

I have a 2011 Chevy also and its smoking under the hood with a little elevated idle, and its not antifreeze. Funny you guys are saying the coolant is over flowing, i cant keep mine full. Have filled it 3 times, taking it back to dealer, upper radiator hose solid as a rock when ice cold... not bad for 4,000 miles.

I have a 2011 Chevy also and its smoking under the hood with a little elevated idle, and its not antifreeze. Funny you guys are saying the coolant is over flowing, i cant keep mine full. Have filled it 3 times, taking it back to dealer, upper radiator hose solid as a rock when ice cold... not bad for 4,000 miles.

I'd say your doing pretty good.. :D

Coolant light keep coming on?

Yes the coolant warning message appears every time...had it to dealer once already and they said we will just top it off, and i said ive done that 3 times lol...im pretty sure its going somewhere, unless the coolant ferry is stealing antifreeze out of my $50,000+ truck

mine was defiantly from when it went in to Regen it smelt like un burnt diesel fuel i was almost to my destination when it did it so i just shut it off and when i did leave 8 hours latter after it warmed up i had considerable amount of smoke cumming out my exhaust. but i didn't mind it looked pretty cool @ night in others headlights getting on the freeway

Its the damm regen cycle

Dealer realigned the downpipe on mine today but said they will call me back in a few weeks because GM is releasing gaskets to address the regen /smoking issue

Had my realingned, 2000 miles later im smoking again!

Does this issue seem to be happening to GMC's more than Chevy's? I'm wondering if it's a manufacturing glitch at the GMC plant if that's the case?

I believe they still come down the same line at the same plant.... or at least they used to when I worked for GM

got a CEL and onstar said it was a turbo related code also. Truck was low on power and ilding a little higher than normal (while smoking from under the hood, which was never fixed by dealer) This paired with the shitty hitch from B&W is really making me pissed off!!

Not a good day for me and the new truck.
Engine light came on today.Called onstar and they said it was something to do with the turbo. Ten minutes later I had some smoke come out the exhaust pipe during regen.Nothing under the hood like some of you guys. This is my fourth regen with 3200 miles on the truck.

Not a good day for me and the new truck.
Engine light came on today.Called onstar and they said it was something to do with the turbo. Ten minutes later I had some smoke come out the exhaust pipe during regen.Nothing under the hood like some of you guys. This is my fourth regen with 3200 miles on the truck.



My understanding from reading the manual is that you will regen every tank of fuel.

Dealer realigned the downpipe on mine today but said they will call me back in a few weeks because GM is releasing gaskets to address the regen /smoking issue

Mine is smoking too. I even noticed a small amount of liquid dripping down underneath my right manifold. It smelled like diesel fuel to me, and at first I thought my fuel filter might be leaking. I took it to the dealer and they checked it out. They couldn't find any leaks, but I had the dealer undercoat my truck at delivery. They said some of the undercoating must have gotten on the manifold, and it was burning off.

I've got about 4000 miles on it now, and it has smoked 3 times--all during regen. After reading this thread, I'm pretty sure mine is smoking for the same reason as everyone elses.

Thanks for keeping this going. I'll call my dealer and inform them, and make sure they get the gaskets.

This thread won't stop me from buying a '11 LML, but it certainly worries me a bit. I wish I had the option of waiting a year or two for the LML to develop (and probably get the cooled seats from the Denali :) ) but I need a truck now. I guess I could always trade-up in a few years, but of course you loose big $ doing that.

-TJ

This thread won't stop me from buying a '11 LML, but it certainly worries me a bit. I wish I had the option of waiting a year or two for the LML to develop (and probably get the cooled seats from the Denali :) ) but I need a truck now. I guess I could always trade-up in a few years, but of course you loose big $ doing that.

-TJ

It shouldn't stop you from getting the truck. I am SO happy with my truck! I've been a truck owner for a long time, and this is by far the greatest truck I've ever owned. The smoking issue is a small detail that is repairable. These things happen, and fortunately, the GM engineers are already on top of it with a fix. You won't regret it.

It shouldn't stop you from getting the truck. I am SO happy with my truck! I've been a truck owner for a long time, and this is by far the greatest truck I've ever owned. The smoking issue is a small detail that is repairable. These things happen, and fortunately, the GM engineers are already on top of it with a fix. You won't regret it.

I agree completely, and if I can locate the truck I want I'll be buying next week. I've always been of the opinion that vehicles have issues, they are machines and machines are not perfect and they are subject to wear. My only problem with that is when a manufacturer can't (or won't) repair an issue with a vehicle.

I had a '06 IS250 that turned out to be a lemon (the early IS250s had issues w/ carbon build-up on the intake valves due to the nature of their direct injection which Lexus cannot resolve). Of course, it actually worked out well for me to have it bought back under Lemon Law but it was a huge PITA going through it.

But the risk of some issues doesn't stop me from buying the vehicle that is right for what I need to do, and what I want. After the Lexus I got a Range Rover Sport Supercharged. As it turns out it was problem-free (I'm probably the only guy who's had a problem free Land Rover product and a Lemon Toyota product, haha) but obviously I knew I was potentially going to have issues. I wouldn't own a LR w/o a warranty, but with one why not? It did everything I wanted at the time great (comfortable DD, room for 4-5, off roads very well, and could tow my 'vette on an open trailer easily). I just decided I wanted to go with a larger enclosed trailer than the RRS SC would accommodate, and I also wanted a pickup bed.

Anyway, sorry to sidetrack the original topic so much. I'm really interested to hear from everybody who's had the issue if/when it returns or if/when it was fully resolved.

Thanks!

-TJ

Chevy will get this fixed up soon I do hope. Won't bash em here. Just glad the 6.7l is doing pretty good. Luck ?

I took my truck into the dealer and guess what they said. No issue that we can find. They said we will have to wait until the problem gets worse to really understand what is going on. These dealers do not seem very motivated to actually troubleshoot the issues. It seems like it either has to not run at all or have a recall notice for your truck to actually get some attention.

I took my truck into the dealer and guess what they said. No issue that we can find. They said we will have to wait until the problem gets worse to really understand what is going on. These dealers do not seem very motivated to actually troubleshoot the issues. It seems like it either has to not run at all or have a recall notice for your truck to actually get some attention.

You don't have to stand for that. Make some noise, demand to talk to the manager of the service dept etc. These are $50-60k trucks, yet we get treated like we bought under $20k econo-boxes? Screw that, my IS250 was only 2/3rds as expensive as the LML I'm going to buy but I got treated like a KING when I took it in for any issue whatsoever. GM has to get this right to compete on the market (especially the world market) and if we just bend over and take it we aren't going to make them change.

-TJ

Just thought I would let yall know what I have seen and found on the new LML trucks. I have had 2 different customers come in complaining about smoke coming from under the hood when driving around town. I found that there is fuel on the out side of the exhaust pipe up by the down pipe. Best I could tell is when going into regen the fuel that is injected in to the down pipe is leaking out of where the 2 pipes come together. I have not confired the smoke concern however did find a doc ID #2531190. The doc talks about realigning the exhaust for a better fit. This is just fyi. Should be no problems with the truck other than the fuel leak. It only happens during regen so the mpg's should not change wheather you have the problem or not.

If you're having trouble with the dealer pinpointing the issue, make sure you reference the above ID#. They can look it up and see what the fix is.

Chevy will get this fixed up soon I do hope. Won't bash em here. Just glad the 6.7l is doing pretty good. Luck ?

Ford just wished a missed aligned exhaust component was their biggest problem to worry about.

I would say GM is doing just fine with the LML.

just talked to my local dealer he hadn't heard about it i gave him the doc # and he said ow ya i see that and there is now a "part" gasket is my guess for them to put in

just talked to my local dealer he hadn't heard about it i gave him the doc # and he said ow ya i see that and there is now a "part" gasket is my guess for them to put in

Yup... I will have mine back tomorrow... sure hope it fixes the problem.

Well I never got my truck back today. They replaced the part the TSB called for and when the service guy was on his way to my office he stopped to fill it up with diesel for me and when he started the truck back up he said it started smoking horribly while he was in traffic and just went straight back to the dealer. So my truck has now spent 8 days of the month at the dealership and I almost certainly will not have it back until atleast Tuesday if I am lucky.

PS: I let my dealer know that if the problem wasnt fixed in 2 weeks I would need a full size truck that could pull my 12k lb race car trailer and tools. I am not putting my racing on hold because of this and I shouldn't have to. I will admit that I still love the truck and want it back. Outside of this problem it is easily the nicest truck on the market... IMO.

Well I never got my truck back today. They replaced the part the TSB called for and when the service guy was on his way to my office he stopped to fill it up with diesel for me and when he started the truck back up he said it started smoking horribly while he was in traffic and just went straight back to the dealer. So my truck has now spent 8 days of the month at the dealership and I almost certainly will not have it back until atleast Tuesday if I am lucky.

PS: I let my dealer know that if the problem wasnt fixed in 2 weeks I would need a full size truck that could pull my 12k lb race car trailer and tools. I am not putting my racing on hold because of this and I shouldn't have to. I will admit that I still love the truck and want it back. Outside of this problem it is easily the nicest truck on the market... IMO.

wow, keep us posted on what they find out about the problem.

Well I never got my truck back today. They replaced the part the TSB called for and when the service guy was on his way to my office he stopped to fill it up with diesel for me and when he started the truck back up he said it started smoking horribly while he was in traffic and just went straight back to the dealer. So my truck has now spent 8 days of the month at the dealership and I almost certainly will not have it back until atleast Tuesday if I am lucky.

PS: I let my dealer know that if the problem wasnt fixed in 2 weeks I would need a full size truck that could pull my 12k lb race car trailer and tools. I am not putting my racing on hold because of this and I shouldn't have to. I will admit that I still love the truck and want it back. Outside of this problem it is easily the nicest truck on the market... IMO.

you need to keep us up to date on this and maybe post a video, i would like to see the smoke..

Ok so as of yesterday my truck has started smoking everytime I drive it also has an increased idle around 800rpm. We just got our first big rain of the year and yes I did find the bigges puddle I could find but that shouldn't have anything to do with it.

And it is not in re-gen

I have read of coolant leaks....... maybe you should look this route. Apparently the coolant is overfilled, and when warmed up, leaks out of the tank, and causes smoking. Maybe this is your problem?

Ford just wished a missed aligned exhaust component was their biggest problem to worry about.

I would say GM is doing just fine with the LML.

Fords 6.7l has very few problems lot less than the lml right now.

Fords 6.7l has very few problems lot less than the lml right now.

Maybe you should buy one then.

Maybe you should buy one then.

It would still be 10 times more reliable than that 6.leaker he is driving.

mine is smoking aswell, i am also getting exhaust into the cab, turned my gas detector on while i was driving and it was reading between 10-15 ppm of CO, kinda is a pain driving down the roads in -20C weather with the windows open. took it to the dealer on friday and told them that i hear there are a few of these trucks having this issue. they called me later on in the day and said they couldn;t find any leak and tried to say they couldn't smell anything. so now i guess i will be driving with exhaust fumes in my truck until they do a recall, cause the service at the dealers here only can repair stuff if it is a recall or there is a code on the computer. seeing i make a living with the truck, i can really afford to let it sit somewhere waiting to get repaired. there now i feel better after gettign that off my chest.

Fords 6.7l has very few problems lot less than the lml right now.

Bullshit

so now i guess i will be driving with exhaust fumes in my truck until they do a recall, cause the service at the dealers here only can repair stuff if it is a recall or there is a code on the computer.

I think a call to GM is in order...they likely can "persuade" the dealer into repairing the problem.

I had an issue with the exhaust leak when I first got my LMM - since it was a lemon replacement it was one of the first MY 2008's off the line in '07. I had it back to the dealer three times before I finally made them force a regen, and then sat in the truck for 20 minutes with the service manager. When his eyes started to water he agreed there was an issue. He called GM, and they had developed the TSB, but had not yet distributed to the dealers yet. They replaced the downpipe and all has been well for 3+ years now...

This isn't a huge secret within GM, nor should it be with the dealer. It's been an issue for going on 4+ years, and if he doesn't want to fix it, then it is indicative of the quality (or lack thereof) the dealership.

I suggest calling GM, calmly explain your issue, and have them call the service manager directly - with you on the line - and see what happens. If the dealer still won't play, have GM set up an appointment at another dealer that gives a shit...

Calling GM is a good idea, anybody have the phone number? Having the same problem with mine. Thanks for all the helpful information.

Calling GM is a good idea, anybody have the phone number? Having the same problem with mine. Thanks for all the helpful information.

For Chevy: 1-800-222-1020 (Canada: 1-800-263-3777)
For GMC: 1-800-462-8782 (Canada: 1-800-462-8782)

thanks for the info. i will be calling tomorrow and i will keep you posted on what comes from it.

I have 1800 miles on my turck and have yet to see smoke, is this an early build issue?

X2 is this an early build issue? To the people with the problem during regen (not the coolant problem), what is your trucks b-day?

It would still be 10 times more reliable than that 6.leaker he is driving.

Wouldn't say that bud 6l can be pretty good with a few basic mods. After 90k mi I would know.

Wouldn't say that bud 6l can be pretty good with a few basic mods. After 90k mi I would know.

Hey powerdog, this thread isn't about you, your trucks, or any Fords for that matter. Those of us who bought LMLs are trying to keep an eye on this thread to see what the resolution for the smoking during regen ends up being just in case we run into the same issue.

-TJ

Wouldn't say that bud 6l can be pretty good with a few basic mods. After 90k mi I would know.


:confused: Since when is putting in head gaskets and studs a easy or basic job on a 6.slow.

this is not an early bird issue i have only had mine for going on 2 weeks but with the service code in post #1 my dealer said there is also a part "gasket" to put in to fix it he had to order the "part" b4 they could fix my truck

My LML is still at the dealer and they called at the end of the day. They are going to take the entire exhaust system off order a few new clamps and realign and install it front to back all over again. They are hoping to have my truck back to me by Wed late afternoon. But there is no guarantee this will fix the problem and the only way for me to find out is drive it around and see if it starts smoking.

I have confidence in my dealer as they have always taken excellent care of me (4 cars in 4 years, plus serviced my LBZ Chevy for me). So I will give them the benefit of the doubt... at least I know I am not the only one with this problem.

PS: They gave me a little Pomtiac G5 for a rental car, at first I was upset, but after realizing I don't "have to have" my truck for anything right now and seeing the MPG the G5 gets I'm not upset one bit! 39.5MPG is 3 times what I was getting in my truck, so at least I have that going for me. Dealer offered to put me in a full size truck on Friday, but the mileage is so good on this thing I am just going to beat around in it.

I will keep everyone posted...

this is not an early bird issue i have only had mine for going on 2 weeks but with the service code in post #1 my dealer said there is also a part "gasket" to put in to fix it he had to order the "part" b4 they could fix my truck

Don't count on that fixing it... Myself and I believe a few others have already had it replaced with no success.

I just picked mine up and started putting miles on it. At about 120 miles it went into it's first regen cycle (I noticed the higher idle). First stop light I smelled diesel and had smoke out of the vents on the hood. Looks like I'll be seeing my dealer again sooner than I thought. :rolleyes:

-TJ

I have 1200 miles on the clock and have not experienced this problem. Fingers crossed.

I have 1200 miles on the clock and have not experienced this problem. Fingers crossed.

Lucky! Also, I'm a little surprised I got my first reg at only 120ish miles.

-TJ

I wonder if the later production trucks were fixed of this problem at the factory. Mine has a production date of 8/10. What are your production dates? You can find it on the driver's door weight sticker.

from what i have noticed it does it at the same spot on my fuel Gage every time so maybe that has something to do with it. maybe just an observation right around 3/4 tank

I wonder if the later production trucks were fixed of this problem at the factory. Mine has a production date of 8/10. What are your production dates? You can find it on the driver's door weight sticker.
mine is 7/10 and it smokes. you have probably not been in stop and go or around town @ a stop light when your truck has gone into re-gen

mine is 7/10 and it smokes. you have probably not been in stop and go or around town @ a stop light when your truck has gone into re-gen

You are most likely correct, my use has been fairly mixed, the longest runs have been two 120 miles runs at hiway speeds, but the rest has been all over including stop and go. I have never noticed any power drop while driving, but I did notice a big MPG drop one time.

Anybody else have a production date?

I wonder if the later production trucks were fixed of this problem at the factory. Mine has a production date of 8/10. What are your production dates? You can find it on the driver's door weight sticker.

Mine is 9/10.

from what i have noticed it does it at the same spot on my fuel Gage every time so maybe that has something to do with it. maybe just an observation right around 3/4 tank

Tank was nearly full.

-TJ

Mine is 9/10.
-TJ

It sounds as though the production date is not an indicator since yours was built after mine.

My truck Is a 6/10 build date and with over 6k miles a lot of it stop and go traffic in Atlanta I have not seen any issues yet. I will keep an eye on it.

I got mine back today and really hope I don't see smoke again... 50 miles and so far so good.

Mine has smoked with a 1/4 tank as well as 3/4 tank and so on, so I wouldn't count on fuel level for much info...

Thanks for keeping this thread going. I'm going to copy all of this to my dealer as soon as someone posts they've got a fix.

Does this issue seem to be happening to GMC's more than Chevy's? I'm wondering if it's a manufacturing glitch at the GMC plant if that's the case?
i am taking delivery of 2011 duramax in 2 weeks from sharrett. i am wondering since you are close by, if you have any advice on the under hood smoke problem? thanks dave. 301 473 1479

Hi Dave, Don't be worried, it seems to be a very small amount of trucks having this problem. I was reading where Ford is having an issue with broken exhaust "flex" pipes and a simular issue and some transmission trouble also. I'll give you a call . Wild Bill

alright so here is an update to my truck and it leak problems, ended up talking to the service manager at the dealer and he got in my truck and said there is defently a bad smell in the cab, they just ordered the parts for the fuel leak issue without looking into the truck to make sure that it was the problem, replaced the parts and suprise no fix, so the truck was there for the week, they went and ordered up all the exhaust gaskets now and are saying that one of them (part# 98065519) is 3 weeks away!! so now is the question can any of you tech's down in the states get your hands on that gasket sooner for me? and for now i guess i either suffer thru the smell for the time being or dont have a truck.

Could it be? if you were to look at the tailpipe design on these trucks you will see they are vented, perhaps to draw in outside air to cool exhaust gasses. another attempt to cut down on emmissions. so let's assume the area where the manifold merges to one is also similar. that might explain the leaking of raw fuel and the smoke. by that i mean these engines need to breath. if this regen cycle were to begin during city driving, there would be back pressure in the exhaust system due to very low rpms, causing the smoke to escape through the area perhaps designed to cool the high temps during regen. the complaints mostly say the smoke appeared when they stopped or slowed,which are both low rpm conditions. i am not making excuses for gm, it's more like wishful thinking. but it does make sense. Could it be?

My understanding is that the fuel, while injected directly into the downpipe just ahead of the metal to metal joint where the downpipe meets the front pipe of the exhaust system, under low speed (and low exhaust speed) allowa a small amount of liquid fuel to seep from the banded joint.

it has to happen while in re-gen, and at low or no speed driving (stop and go city traffic)

I have only seen it one time, while making several stops in town, where the short runs weren't enough to let the truck complete it's re-gen.

So, IMO out of the nearly 9000 miles I have driven this truck, I noticed it for about 30 seconds, I am not even considering it an issue.

When, and if I ever have into the dealer for some legitimate issue, I might mention it, otherwise I probably wont even deal with it

I have put 400 miles on mine since my dealer installed the new clamp and realigned the entire exhaust system. No problems... I am having the Dealer install my Banks Exhaust for me this week. So things are looking up for me with resolving this issue.

my truck is leaking all the time, not just in regen, i do 95% hwy driving and you can still smell exhaust driving at 120km/hr. so it is something that i cant say is not an issue.

I just took my LML on a trip towing a 33' toy hauler 5th wheel had about 1800 miles recorded on the odometer and it was smoking like a freight train in heat before I started to take a large grade and said no way I'm I continuing up that mountain. I used my Onstar to help locate the nearest Chevy dealership the day before Thanksgiving and the Bakersfield, Ca dealership was nice enough too take on the job they new right away what the problem was. They've said there was a bulletin out on the gasket for the DEF tank that wasn't tightend at the factory it should either be tightened or replaced I had mine replaced also they've noticed a small fuel leak coming from the fuel lines leading to the fuel tank. All problems solved and corrected and I was back on my way to the desert in southern ca without any further issues.

Thank you for all of this, my dealer thought I was being an pain in the rear about this issue, it would not happen for them so there for they could not say or do anything for me.

I now have 8,000 plus miles on the truck and i will say it has not happened for about 4,000 miles, but in the first 4,000 miles it happened alot

experienced the smoking form under the hood today during my first regen(420 mi.), will be showing this thread to my dealer asap.

Called my dealer and had them pull up this thread. I want to get the truck in during the next couple of weeks, and asked them to do some research into this and get the parts needed. These guys have always been pretty good, so I'm hoping mine is going to get fixed before year's end.

1000 miles on mine since the dealer realigned the exhaust and installed the new clamp. No problems!

and the leak is fixed!!! it took them 3 days of shop time to get it but they finally got it. i can now drive withouth having to have my windows open to breath. they changed out all the gaskets from the headers to the turbo.

I got the strong odor of diesel fuel yesterday and got to the store and had smoke coming from the right side of the hood. Three thousand miles and this is the first time it happened to me where I have noticed. Called the dealer and they have ordered the part. It steered them to this web site. They said GM is aware of the problem.

I have 5000 miles on my Denali HD and have experienced the smell of diesel burning or smoke coming from the hood a few times during the DPF soot burn off that takes place every 600-700 miles. I took it to my dealer this week and they performed the exhaust realignment as recommended by GM in an earlier post in this thread. The leaking diesel was coming from a loose connection where the exhaust pipe and down pipe from the turbo come together at the clamp location. The issue is an alignment issue which causes the clamped area to leak diesel or DEF at times. Diesel leaks and then runs down the exhaust pipe and burns causing the smoke. Alignment and tightening this clamp should take care of the issue. I had them change the oil and rotate the tires. The truck drives beautiful, gets 18 mpg average and has had no other problems to take care of. At 70 mph on an interstate I get 20 mpg with ease. These are great HD trucks with a quiet and excellent ride.

ken, a very informative report, good to hear the problem was easy to remedy. And I am pleased to see your mpg is impressive, got to love the Denali HD LML.

well i had to take my truck back in today, went to drive out to work this morning and was at a light when all of a sudden i could smell diesel, a second later my cab filled with exhaust and was coming out of my hood aswell, drove to the dealer and they got the truck in right away. apparently the exhaust injector decided to fall out, so there was my diesel smell, and they also found another exhaust leak somewhere. not to sure where yet but will find out in the morning when i pick it up.

well i had to take my truck back in today, went to drive out to work this morning and was at a light when all of a sudden i could smell diesel, a second later my cab filled with exhaust and was coming out of my hood aswell, drove to the dealer and they got the truck in right away. apparently the exhaust injector decided to fall out, so there was my diesel smell, and they also found another exhaust leak somewhere. not to sure where yet but will find out in the morning when i pick it up.

Sell that baby back to the dealer and buy another. When it gets to the point where a truck is having to go back to the service dept, for the same issues or different ones all the time. Its time to part ways with it IMHO.

Well, I got a regen as I was getting to my office the other day. Inside the parking garage it was really obvious that smoke was pouring out of the cowl vent pretty bad. I dropped the truck off yesterday to address that and my P0299 codes (3 Check Engine lights now). I haven't gotten the call yet today on status, but yesterday he confirmed they were ordering the gasket or whatever it is and were going to reflash the PCM.

-TJ

Well...had my first regen since the dealer replaced the gaskets and realigned the downpipe, and I had smoke again. It wasn't as pronounced as it was before, and it wasn't coming into the cab like it did before. But when I pulled the truck into the garage and got out, I could smell the smoke fumes on the passenger side. Taking it back into the dealer tomorrow. Dangit!

How many miles? Could it just be factory stuff burning off?

[QUOTE=wreedLBZ;4186947]How many miles? Could it just be factory stuff burning off?[/QUOTE

Just over 5000 miles. I've had it in 3 times for the same thing. The first time that's what they thought. Happens every time it goes into regen.

Wow I feel special, 2000 miles with no issues whatsoever. Just went out and crawled under my truck to check the downpipe and nothing, completly dry and my DIC hasn't displayed low DEF messages either. Sorry to rain on your parade guys,lol. =) LOVE the truck, true beast.

Wow I feel special, 2000 miles with no issues whatsoever. Just went out and crawled under my truck to check the downpipe and nothing, completly dry and my DIC hasn't displayed low DEF messages either. Sorry to rain on your parade guys,lol. =) LOVE the truck, true beast.

No worries about raining on my parade. I love the truck, and its the best truck on the market. Its a little frustrating to take it in over and over, but i'm confident it will get fixed. I plan to own this truck a long time.

Ya I hear ya. I plan on having this truck a LONG time. I wonder is production date could have anything to do this these problems guys are having. I only wonder this because my truck didn't roll off the line until mid/late DEC. Just a thought I have no way of knowing how long everybody has had their trucks.

Ya I hear ya. I plan on having this truck a LONG time. I wonder is production date could have anything to do this these problems guys are having. I only wonder this because my truck didn't roll off the line until mid/late DEC. Just a thought I have no way of knowing how long everybody has had their trucks.

Its possible. I bought mine back in August 2010. I'd hope that if GM started getting feedback of these downpipes leaking that they'd fix the problem on assembly.

I had a regen the other day, no smoke just awful smell. it was the first one i believ.

I had a regen the other day, no smoke just awful smell. it was the first one i believ.

What did it smell like, and where was the smell coming from?

All around the truck but more like it was coming from the engine compartment, exhaust system.

All around the truck but more like it was coming from the engine compartment, exhaust system.

If its the problem with the downpipe (that everyone is writing about in this thread), what you'll smell is diesel fuel that is burning on the hot pipe. Evidently there is an injector located inside the pipe,and when the truck goes into regen fuel leaks out. You can usually smell it most profoundly on the passenger side. Before they realigned my downpipe, I could smell it inside my cab. This last time, I could only smell it near the wheel well and around the passenger side front fender.

No smell of diesel and no smell in the cab. hopefully i got a good one!

Well...had my first regen since the dealer replaced the gaskets and realigned the downpipe, and I had smoke again. It wasn't as pronounced as it was before, and it wasn't coming into the cab like it did before. But when I pulled the truck into the garage and got out, I could smell the smoke fumes on the passenger side. Taking it back into the dealer tomorrow. Dangit!

Sorry to hear, please keep us posted. Thanks.

Does build date have anything to do with it?
My truck was built Nov 10

All - Not sure if this is a re-post since I did not read through all of the messages. On the right side of the engine bay firewall, down at the bottom, there is a small hose that serves as an HVAC drain. The end of this hose needs to be turned to approximately a 8:00 position as viewed on a clock. That allows for good drainage and prevents moisture from dripping on the exhaust. The drip on the exhaust leads to smoke under the hood and a faint smell of diesel. I drove a 2011 pre-production model LML and had this issue. Simply turning the hose fixed the problem. I know it sounds a little silly, but it the truth. I build these trucks in Fort Wayne, IN and can assure you that we are dong everything we can to make them right - the diesels all get extra attention. Thanks - Michael

Just picked my truck up from dealer. They had to overnight the gasket seal, and performed another realignment. This time the forced the truck into a regen to monitor the exhaust. They found no leakage and no diesel fumes. Let's hope this solves the problem. The tech said that there is now a full write up on the issue. The number that is on my service record is 71-915877282.

All - Not sure if this is a re-post since I did not read through all of the messages. On the right side of the engine bay firewall, down at the bottom, there is a small hose that serves as an HVAC drain. The end of this hose needs to be turned to approximately a 8:00 position as viewed on a clock. That allows for good drainage and prevents moisture from dripping on the exhaust. The drip on the exhaust leads to smoke under the hood and a faint smell of diesel. I drove a 2011 pre-production model LML and had this issue. Simply turning the hose fixed the problem. I know it sounds a little silly, but it the truth. I build these trucks in Fort Wayne, IN and can assure you that we are dong everything we can to make them right - the diesels all get extra attention. Thanks - Michael

Make sure mine is done properly as it's being built now! ;)

Just picked my truck up from dealer. They had to overnight the gasket seal, and performed another realignment. This time the forced the truck into a regen to monitor the exhaust. They found no leakage and no diesel fumes. Let's hope this solves the problem. The tech said that there is now a full write up on the issue. The number that is on my service record is 71-915877282.
That is a case number for the tech and TAC. It wont help you any unless the problem comes back. If it does make sure to tell the writer the number and make sure they give it to the tech. It will make them aware that there is an on going problem with your truck.

I read through this whole thread and want my 13 clicks back it took to make it to where I'm at now. This illusive gasket thats mentioned, is it for the turbo down pipe to cat up pipe connection? I've had one come in twice for smoke under the hood and I've aligned the exhaust perfectly and its still leaking out and running down the pipe. I had to put an engine in a couple weeks ago on a different truck and the engine engine which came complete had a different style down pipe on it. The flange had a sort of shoulder made onto it that the cat up pipe fit over and kept things aligned nicely so all I had to do was throw the clamp on and tighten it down. They should have done that years ago. I searched everywhere I could and didn't find anything but the realign the exhaust and hope it works bulletin so I ordered the turbo down pipe to see if we get the same one that was on the new engine I put in a while back. If that does work I don't know what to do. Its such a simple deal that was never a problem until now.

I reread over the bulletin and it appears the illusive gasket everyone is referring to is just the 4 bolt hole gasket for the cat to DPF connection, not some type of gasket that goes up on the down pipe to cat pipe band clamp connection. Had another come in friday smoking from under the hood, one that I've realigned the exhaust on already. The cat pipe was completely covered in diesel. I've got the thing aligned as good as its going to get. My only other idea is applying a thick bead of RTV ultra copper high temp silicone to the connection unless tech assistance has a better idea. The only thing I'm not sure about is the high temp RTV is only rated to 700 degrees. Thoughts or opinions?

Just for everyone's information. Mine is still smoking from the exhaust/9th injector/alignment issue. It is going back in the shop for the 7th time next week. If they don't fix it this time. changing dealership and then I am moving towards "Lemon Law". This is really getting OLD and on top of that it is embarrassing; smoke boiling out from underneath of a $50,000 brand new truck!