Smoke and burning smell under hood LZ0 3.0L Duramax

[Waterfowler]

Just picked up my first GMC two weeks ago. 2023 AT4 1500 with the new LZ0 motor. One week after purchase, 300 miles on truck, sitting at traffic light and see white smoke coming out between back of hood and bottom of windshield.

Schedule an appointment at dealer last week but was canceled due to hurricane. Driving home tonight, 690 miles on truck, sitting at light and started smelling smoke again. Dark outside and couldn’t see smoke but could definitely smell it. Popped hood when I got home, definitely smells like something burning.

Anyone else experience this with previous 3L Duramax or new LZ0? Calling dealership again in the morning.

 

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[Rle312]

I've got the same set up on ordern, would like to see how this turns out.

 

[Andystoy AT4]

SWAG is that your truck was going through a regen, which raises the temperature of the exhaust components and the coating burns off. If you didn't get any codes all should be okay but let us know what your dealer finds.

 

[zeeya]

That is a good possibility due to first re-gen. My exhaust temps usually run about 600 driving at 75, but when regen starts it will get up to 1100 degrees.

 

[Waterfowler]

Went to the dealer on Friday. They had the truck up on a lift for 30 minutes looking for leaks, loose connections or anything that would have produced smoke. They couldn’t find anything wrong.

I did mention a regen and the service advisor stated she said she has never heard of that before. That’s concerning ….

 

[TB_Rider]

My first couple regens caused my eyes to water and was very noticeable when stopped at a light.

 

[Waterfowler]

My first couple regens caused my eyes to water and was very noticeable when stopped at a light.

TB_Rider: How often did this happen for you ? Is there an average mileage between each regen? Mine occurred around 300 and 700 miles

 

[AT802A]

My 23 lzo did it as well on the first regen at about 350miles since new. It returned to normal afterwards. I seem to remember my 2020 2500 Duramax doing the same thing, totally normal

 

[zeeya]

TB_Rider: How often did this happen for you ? Is there an average mileage between each regen? Mine occurred around 300 and 700 miles

Waterfowler, I was in that nasty rain today chasing those ducks... The regen on my 21 differs greatly. When driving in town on my two weeks off, it may go 80-100 miles between regen. Exhaust temps do not get hot enough to keep the filter clean, but when I am traveling on the interstate at 75-80, sometimes it will go 400 miles between the regens.

 

[by350]

I got a 2022 Sierra AT4 with the Duramax motor about six weeks ago and experienced a very bad burning smell coming from the engine compartment. It seems like it's going away, but it was quite strong for several days in a row.

 

[Waterfowler]

Just checking do you guys smell this inside the cab of the truck? I can smell the burning smell coming through the air vents. Wouldn’t diesel Regen burn off what’s inside the exhaust resulting in a smell/smoke coming from the tail pipes and not the engine compartment?

Mine happened again just now sitting in parking lot of a restaurant

 

[Andystoy AT4]

Regen causes the exhaust temperature to increase well above the temperature reached when you are driving normally. When the extra diesel is injected into the exhaust stream after the normal combustion, the extra diesel raises the temperature inside the DPF system to burn off the soot particles trapped in the diesel particulate filter and this raises the temperature all along the exhaust system including the shields etc. that are in place to protect the components next to them from getting burnt. The exhaust system and the shields themselves may appear to be smoking if you looked at the turbo etc. during the first or second regen. This is completely normal and goes away once the coating has been burnt off. JMO

 

[Waterfowler]

Really starting to wonder if my truck has an issues. This regent has now happened twice within 3 days. The smell coming in the cab of the truck will take your breath away. This morning the MPG dropped down to around 18-19 driving to work, notice the idle increased sitting at a traffic light then that chemical smell started coming through air vents.

This is happening much more than anyone has described or that I’ve read about

 

[zeeya]

Really starting to wonder if my truck has an issues. This regent has now happened twice within 3 days. The smell coming in the cab of the truck will take your breath away. This morning the MPG dropped down to around 18-19 driving to work, notice the idle increased sitting at a traffic light then that chemical smell started coming through air vents.

This is happening much more than anyone has described or that I’ve read about

Just driving in town 10-15 miles a day, mine will Regen around 100 miles, interstate at 75, I’ve gone 400

 

[Waterfowler]

Does anyone use Hotshot? If so does reduce Regen frequency as their product claims ?