3.0L Duramax - who owns or has driven one

Duramax3oh · March 4, 2020

Can someone share what the “regen” is, what it accomplishes, and how often this should happen?

I’m about 2,000 miles in and haven’t noticed it at all. Is there an alert for when it happens?

becker87 · March 4, 2020

Can someone share what the “regen” is, what it accomplishes, and how often this should happen?

I’m about 2,000 miles in and haven’t noticed it at all. Is there an alert for when it happens?

The Regen is there to burn if extra soot trapped in the exhaust system. All modern diesels have them. You may not notice every time you go through a Regen. I only notice it when my window is down or I pull into the garage and turn it off and I can smell it as i get out. Doesn't really smell bad, just different, like really hot metal as it has to heat up to over 400 degrees I believe.

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becker87 · March 4, 2020

Can someone share what the “regen” is, what it accomplishes, and how often this should happen?

I’m about 2,000 miles in and haven’t noticed it at all. Is there an alert for when it happens?

Also there are no alerts when it happens. I would guess there is an alert after the process gets interrupted after to many times to say you must drive for a prolonged period of time. I have not gotten any message like that yet and I have interrupted the process a few times but typically my next drive is long enough to complete

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Cpl_Punishment · March 4, 2020

Given that diesels burn essentially no fuel at idle, auto stop on this engine seems stupid to me.

Gswartz · March 4, 2020

On 3/3/2020 at 4:33 AM, HondaHawkGT said:

No more than it would cost to replace the timing chains or belt on a DOHC engine, which is a scheduled maintenance item for most of them and take as much or more work to change. Ford has used a similar wet belt oil pump setup for roughly 10 years now on one of their engines.

I’d be willing to bet it will be substantially easier to replace than most timing belts. No timing required for the belt. “Just” pull the tranny back a few inches and pull the flex plate and cover. New belt and reverse. Pretty hard to mess that up.

Duramax3oh · March 4, 2020

On 3/3/2020 at 12:19 PM, HondaHawkGT said:

Yeah 20 mile trips are fine. I mainly meant it as a cautionary thing for anyone considering the LM2 and are kind unsure about it. Some people do a ton of short trips in these newer diesels and end up with a ton of problems because they don't understand just how bad it is for the expensive filters on these things.

On 3/3/2020 at 11:13 AM, redwngr said:

Because water is a byproduct of combustion, and water will condense out of the exhaust stream when the engine and exhaust or not hot enough.

This is true for both gas and diesel engines.

It's not the start and stop that causes the problem -- it's the cold running / not running long enough to get warmed up enough that the moisture can be carried out.

This is good stuff guys, thanks for the info.

Next question... Does the natural climate make any meaningful impact towards this "issue/problem"? I.e. I live in Houston, TX where it's rarely ever freezing and usually 80-90+ degrees out. Would these short trips become a non-factor? Systems may warm up extremely quickly (and/or not cool down as quickly). Or Be slightly less of a factor than living in cold climate... or have virtually no impact on it being warmed up to the point short trips will still cause this "existential threat" to the engine?

Thanks in advance

Edited March 4, 2020 by Duramax3oh

redwngr · March 4, 2020

2 minutes ago, Duramax3oh said:

This is good stuff guys, thanks for the info.

Next question... Does the natural climate make any meaningful impact towards this "issue/problem"? I.e. I live in Houston, TX where it's rarely ever freezing and usually 80-90+ degrees out. Would these short trips become a non-factor? Systems may warm up extremely quickly. Or Be slightly less of a factor than living in cold climate... or have virtually no impact on it being warmed up to the point short trips won't cause this "threat" to the engine?

Thanks in advance

Too many variables to have a firm black/white answer.

How long are the trips?

How much (cool down) time between them?

Does it also get used for longer runs?

etc ...etc...

Imho, everyone is overthinking this.

All gas/diesel engines need to be warmed up to work most efficiently and to not have issues with condensation. OTOH, the number of vehicles that never get warmed up must be very low.

Drive it and don't worry about it.

Jim71 · March 5, 2020

I’m right at 10,000 miles ,this truck is really nice .Cant day enough about the great power around town.Easily the best 1/2 ton diesel.

becker87 · March 5, 2020

Well I finally did it. Took of the duratracs for some Cooper AT3 XLT to try and get some mileage back as well as no more road noise. On the way back to the office seemed to be a little better, around 10% it seems, closer to stock. Still running the 275/70/18

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newdude · March 5, 2020

On 3/3/2020 at 10:57 PM, Duramax3oh said:

Can someone share what the “regen” is, what it accomplishes, and how often this should happen?

I’m about 2,000 miles in and haven’t noticed it at all. Is there an alert for when it happens?

No alerts, no lights.

Regen is the process in when the diesel particulate filter "regenerates", aka cleans the soot the trap accumulates. This typically occurs once per tank of fuel. There are pressure sensors at the front and rear of the filter. They monitor the differential in pressure before and after the trap to calculate the soot load in the DPF. When it reaches an appropriate level, the truck will initiate a regen. There is a hydrocarbon injector (7th fuel injector) that doses hydrocarbons (diesel fuel) to ignite the trap and start/maintain the regen process. Temps typically get in the 1100-1300 degree F range during a regen if you monitor via an OBDII software such as BlueDriver.

The most common sight to see is a higher idle when in gear. For example, on my 2016 Colorado diesel, it would idle about 700rpm normally, and during a regen would idle at 900-1000rpm. This was noticeable on the tachometer, and was audible in that you could hear the idle was slightly elevated. You may also notice a stronger odor when stopped at a light during a regen. From my experience, its similar to the normal smell of these engines, but add in some old school diesel aroma, and it smells "hotter" as well.

Another very common telltale of a regen is your instant fuel economy. For example, my Colorado. At 65mph, it toggled between 30-34mpg. During regen, it was almost always 19-22mpg on the live readout.

You can if you had to, shut off the truck during a regen. If that were to occur, there will be a message in the DIC stating for you to drive the vehicle at XXmph to perform the regen. If you are able at all over your time of owning it, pick up on when its doing a regen, driving through the whole thing ensures a proper burn of the DPF.

ian cloutier · March 8, 2020

I picked one up last week, 500kms on it now.

SWD · March 8, 2020

Have 2020 GMC Sierra crew cab 4x4, with the 3.0 liter and have had no problems, Bought it Oct. 2019 attached is the latest mileage from a 2 hour trip in New Hampshire up north driving 55 mph average over 40 mpg on this trip got a high of 42.4 as the best. Have just over 3500 miles on it.

ian cloutier · March 9, 2020

I found this supplement in my warranty booklet, am I reading this right, our 3L Diesel’s get 5 year/ 160,000km (100,000mile) powertrain warranty instead of the typical 100km?

davester · March 9, 2020

Yes, you are reading that correctly.

redwngr · March 9, 2020

9 hours ago, ian cloutier said:

I found this supplement in my warranty booklet, am I reading this right, our 3L Diesel’s get 5 year/ 160,000km (100,000mile) powertrain warranty instead of the typical 100km?

It's been that way with the big brother -- 5 yr, 100,000 mile / 160,000 km powertrain.

Rest of truck same as the gasser.

Edited March 9, 2020 by redwngr