3.0 Duramax exhaust smell in cab

davidr83 · January 12, 2021

55 minutes ago, OliverDennis52 said:

Let us know what they find. I also get the exhaust odor in the cabin on COLD starts, worse when in the garage and not so bad outside. I'm currently waiting on part for the radio, so when I take it back in I'm going to have them check this. I assumed it was "normal" being my first diesel since it's not super annoying and goes away once I start moving. I'm curious if most 3.0 owners don't get any exhaust odor at all on cold starts...

Ive never had any, just the burning smell when it was new.

Kchampagne · January 19, 2021

Well, mine is back in for the third time for the same exhaust smell in the cab. Not as bad as the last time, but still problematic. Cold start, idle in park, then can smell exhaust after about 90 seconds. It has to be that Def injector clamp. This sucks.

IcemanNY · January 19, 2021

Update: Dealership smoke tested the exhaust and found leaks at both ends of the down pipe off the turbo. They removed it and found some “debris” causing the gaskets to not seal properly. New gaskets and it seems ok.

kpromero · January 22, 2021

I have been noticing as well and just chalked it up to a new truck, 120 miles on it. It got soo bad today driving around and I switched the AC to recirculate and the smell stopped.

OliverDennis52 · January 22, 2021

Dropping mine off Monday. I'll post back results when I get them...

Crazypontiac03 · January 24, 2021

Mine does this too,m. I just thought it was normal since it’s normally being auto started in the garage. I guess next time Its in for service I’ll have it checked since I was just they’re today.

OliverDennis52 · January 29, 2021

Just picked up from dealer last night. Exhaust back pressure valve leak, so they replaced the valve and associated gaskets. I only drove it home and haven't had a cold start yet. Hoping this cures it.

IcemanNY · February 12, 2021

Well, the truck has been back to the dealer again. The smell is strong but this time it is a distinct fuel smell. It smells like there is fuel leaking outside the truck and that in turn gets in the cab. Only happens on cold start and is gone once the truck warms up. Dealer said it was faulty #6 cylinder injector. Replaced it and it still does it. Truck even seems to stumble and hesitate for the first few minutes of driving, almost like its loaded up from too much fuel and once cleaned out its fine. It also has a strong antifreeze smell coming from behind the right headlight- which of course shows no sign of leaks anywhere. Wondering if maybe I got a Monday or Friday build. Is anyone experiencing any of these problems? It’s got 2700 miles now and I’m about to pursue either a buyback or lemon law here in NY. This will be it’s 4th time back to the dealer for the same problem in the last 2 months.

Z45 · February 12, 2021

fyi........................

Quote

Exhaust Odor in Cabin or Engine Compartment

February 10, 2021

An exhaust odor in the cabin or in the engine compartment may be noticed on some 2020-2021 Silverado and Sierra models and 2021 Tahoe, Suburban, Yukon, and Escalade models, equipped with the 3.0L diesel engine (RPO LM2). The exhaust odor may be caused by an improper weld on the exhaust backpressure valve. (Fig. 21)

If an exhaust odor is present, test for a leaking exhaust backpressure valve weld joint using the GE-52250 Power Smoke Diagnostic Leak Detector or soapy water. Refer to the latest version of #PIP5684 for more information on using the GE-52250 detector.

The exhaust backpressure valve is located between the downpipe from the Selective Catalyst Reduction (SCR) with filter and the underfloor SCR.

Smoke from the GE-52250 detector may not get through the Diesel Particulate Filter (DPF), so test downstream in the exhaust system by administering the smoke at the fitting on the tailpipe bladder seal. The tailpipe bladder seal does not reach the exhaust cooler, so it will be necessary to wrap duct tape around the tailpipe to seal the cooler holes. Be sure to remove the duct tape from the exhaust cooler after completing testing.

Repair any leaks identified after testing the exhaust system components. An ineffective weld at the flange joint may be a source of a leak. (Fig. 22) If the weld joint is leaking, replace the exhaust backpressure valve.

Edited February 12, 2021 by elcamino

Kchampagne · February 12, 2021

3 hours ago, elcamino said:

fyi........................

Thanks! Is there a TSB # associated with this? Perfect timing. Mine is going back to the shop for the 4th time.

Z45 · February 12, 2021

1 hour ago, Kchampagne said:

Thanks! Is there a TSB # associated with this? Perfect timing. Mine is going back to the shop for the 4th time.

Don't think so, just posted 2 days ago so I think they recently discovered the flaw.

https://gm-techlink.com/?p=14365

Edited February 12, 2021 by elcamino

gemarsh · February 12, 2021

17 hours ago, IcemanNY said:

Well, the truck has been back to the dealer again. The smell is strong but this time it is a distinct fuel smell. It smells like there is fuel leaking outside the truck and that in turn gets in the cab. Only happens on cold start and is gone once the truck warms up. Dealer said it was faulty #6 cylinder injector. Replaced it and it still does it. Truck even seems to stumble and hesitate for the first few minutes of driving, almost like its loaded up from too much fuel and once cleaned out its fine. It also has a strong antifreeze smell coming from behind the right headlight- which of course shows no sign of leaks anywhere. Wondering if maybe I got a Monday or Friday build. Is anyone experiencing any of these problems? It’s got 2700 miles now and I’m about to pursue either a buyback or lemon law here in NY. This will be it’s 4th time back to the dealer for the same problem in the last 2 months.

I'm sorry to read about your trucks trouble. Ain't nothing worse than to have to worry about a vehicle that can't be depended on, specially new. I have read other members posts with all sorts of issues also. I keep waiting for a check engine light to come on, or a derate, or a rear window leak, or a broken valve spring or a blue screen infotainment center, or no brakes, or oil puking out the rear main seal, or if my state has lemon laws.

I must have won the lottery and acquired a truck built at 10am on a Tuesday, or they pay more attention to a Denali. Which I don't think are true, but something must be going on. It's hard to decipher if these posts are about a chevy or gmc or both. Aren't both of these trucks made on the same line at the same time? Like a GMC Denali is rolling right behind a Chevy WT? Or is it a weeks worth of Denalis and then a weeks worth of High Country’s?

I don't understand how one truck can have problems and the next truck has none. Or if we are just seeing posts of problems on this site, and it's 1 truck out of 10,000 trucks with problems.

redwngr · February 13, 2021

7 hours ago, gemarsh said:

I'm sorry to read about your trucks trouble. Ain't nothing worse than to have to worry about a vehicle that can't be depended on, specially new. I have read other members posts with all sorts of issues also. I keep waiting for a check engine light to come on, or a derate, or a rear window leak, or a broken valve spring or a blue screen infotainment center, or no brakes, or oil puking out the rear main seal, or if my state has lemon laws.

I must have won the lottery and acquired a truck built at 10am on a Tuesday, or they pay more attention to a Denali. Which I don't think are true, but something must be going on. It's hard to decipher if these posts are about a chevy or gmc or both. Aren't both of these trucks made on the same line at the same time? Like a GMC Denali is rolling right behind a Chevy WT? Or is it a weeks worth of Denalis and then a weeks worth of High Country’s?

I don't understand how one truck can have problems and the next truck has none. Or if we are just seeing posts of problems on this site, and it's 1 truck out of 10,000 trucks with problems.

Watching posts from new members, it seems that people generally join cuz they are enthusiasts or have a problem and want an opinion. Often, after a few posts about the problem, many disappear - perhaps not even posting back about the resolution to the issue.

They rarely have come hunting for a forum to join to make a post about how good the new truck is. So it seems there is amplification of problems by the forums, as you last line suggests.

Don't forget that GM is building about 3000 full size pickups per week (they plants don't run 52 weeks per year)

GMC/Chev are mixed on the line. The items that make them trucks are the same. The rest is just trim.

When a frame leaves the supplier or an engine leaves GM powertrain plant, no one knows if it's going into a chev or gmc and no one know what trim level the truck is going to be. (well, ok, some engines only go in certain levels...)

Edited February 13, 2021 by redwngr

gemarsh · March 3, 2021

On 2/11/2021 at 7:38 PM, IcemanNY said:

Well, the truck has been back to the dealer again. The smell is strong but this time it is a distinct fuel smell. It smells like there is fuel leaking outside the truck and that in turn gets in the cab. Only happens on cold start and is gone once the truck warms up. Dealer said it was faulty #6 cylinder injector. Replaced it and it still does it. Truck even seems to stumble and hesitate for the first few minutes of driving, almost like its loaded up from too much fuel and once cleaned out its fine. It also has a strong antifreeze smell coming from behind the right headlight- which of course shows no sign of leaks anywhere. Wondering if maybe I got a Monday or Friday build. Is anyone experiencing any of these problems? It’s got 2700 miles now and I’m about to pursue either a buyback or lemon law here in NY. This will be it’s 4th time back to the dealer for the same problem in the last 2 months.

So has this been fixed for you?

I get a whiff of diesel smoke once in a while. Guess its been there from new, just didn't know it was wrong. Doesn't bother me or the wife. As we farm and none of the machinery is new enough to have any diesel emissions, cept for a 2017 CAT mtl.

All of them blow black coals out of the exhaust.

I might be a little corrupt, cause I actually enjoy the diesel smoke smell.

IcemanNY · March 3, 2021

Nope, it hasn’t been fixed. It has now been to two different dealers both of which confirm there is a strong fuel smell. I get the same response, that the engine is so new they don’t have enough familiarity with them to diagnose and fix them yet. Ive been in contact with my salesman to see where we go from here.