2020 1500 duramax

Mike Bullock · December 29, 2021

I have a 2020 1500 3.0 duramax that has run on the warm side of 210 degrees since new, at 30,000 miles it overheats regularly.

I have taken it in to the dealership for service every 5,000 miles and told them about the overheating, their answer is these trucks run warmer because of the DEF system and they said they could not get it to overheat. Any ideas or help would be much appreciated

Rrc91724 · December 31, 2021

My truck runs a little warmer when it Regens but that's expected. Never had an issue with overheating tho. The DPF is what heats up at Regen the DEF is sprayed into the DPF to remove particulate buildup. Do you get a check engine light or overheating warning on the dash?

CamGTP · December 31, 2021

Define overheating.

Like it gets to 240-250 degrees and shuts the truck down type warm?

Just a FYI, the gas engines will get to 220-230 on a normal basis if they are put under heavy load for long enough and for sure in the summer. That is completely normal for the stock temp thermostat and factory fan settings.

Mike Bullock · December 31, 2021

Thank you. It it does that also, but I drive 23 miles to work, last week it was 74 degrees and 3 days when I got home it has went way up and blowing coolant out. I have to add coolant about once a month. The dealership says this in normal

redwngr · January 24, 2022

On 12/31/2021 at 3:50 AM, Mike Bullock said:

Thank you. It it does that also, but I drive 23 miles to work, last week it was 74 degrees and 3 days when I got home it has went way up and blowing coolant out. I have to add coolant about once a month. The dealership says this in normal

That's definitely not normal.

Issue with the fancy coolant distribution valve perhaps?

Is it a service advisor you're talking to, or have you escalated up the chain?

Back of the OM has the steps GM suggests for 'escalation'.

Be pleasant, keep records.

Fwiw, my LM2 is just over 16,000 miles.

I've only added a little to mine. It's not on ignore, I do check from time to time.

It does the thing where the gauge runs a little higher before the distribution valve settles in.

It's never 'blown coolant'.

Probably get more reads/responses in the sierra/silverado troubleshooting section or engines section instead of here in 'future speculation'

Edited January 24, 2022 by redwngr

20Denali22 · February 2, 2022

On 12/31/2021 at 3:50 AM, Mike Bullock said:

Thank you. It it does that also, but I drive 23 miles to work, last week it was 74 degrees and 3 days when I got home it has went way up and blowing coolant out. I have to add coolant about once a month. The dealership says this in normal

The 6.6's get hot like this when the head gasket blows too. Any black flakes of carbon floating around the expansion tank?

DemonWorks · March 2, 2022

I had a 2020 Duramax and it ran the temp up all of the time. Near 3/4 on the gauge. Never had to add coolant.

My 2021 does not do this, it rarely goes above half and i'm ok with that !

From my learning on these trucks, the 2020 will go up and back down on temp. The key is that it goes back down...

If you are having to add coolant, there is an issue. If it's just a temp gauge getting higher than you like to see, that is unfortunately the way most of the 2020 trucks are.