3.0 Duramax engine temp erratic going all the way up to redline 260 degrees, heater blowing cold air

[Russell Kutach]

I have 69k on my AT4 with 3.0 duramax and the engine temp started to rise erratically including all the way up to 260 degrees which is redline.  This just started happening and I have never seen it get above 220 since it was new with zero miles on it.  The trucks cabin heater is also working erratically and blows COLD air even when the engine temp goes up to 225-245.  Its really cold right now with an arctic blast driving temps here in Houston down to 18 degrees so ambient is between 18 and 32 and this is still happening.  I NEED cabin heat!!!  I cannot swallow the fact that these engines like to run hot because this just started and the heater issue came along with the engine overheating issue all at the same time.  anyone having the same problems?? 

Edited December 24, 2022 by Russell Kutach
added information

[SteveP45]

is the thermostat stuck and not allowing the hot coolant to flow through the heater core?

Edited December 24, 2022 by SteveP45
word correction

[SteveP45]

I meant coolant, not water

[Russell Kutach]

Steve, im not sure how to check this...

 

[David Krueger]

Check your anti freeze level.

In the radiator not just the reservoir. 

[silveradosid]

on larger diesel engines this is a sign of a head gasket failure, air at the temp sender, so it is reading the casting temp not coolant, no heat is because the heater is being filled with air

[Russell Kutach]

Since this engine has louvers/dampers and can redirect coolant to different areas, I would also suspect the thermostat (if it has one) could be inop therefore causing the computer to get confused and causing the erratic shifts in temp.  Im taking it into the dealer thursday so I will post what they find at that time....  dont want to kill my 60k investment.

[GMCustomerService]

On 12/23/2022 at 7:19 PM, Russell Kutach said:

I have 69k on my AT4 with 3.0 duramax and the engine temp started to rise erratically including all the way up to 260 degrees which is redline.  This just started happening and I have never seen it get above 220 since it was new with zero miles on it.  The trucks cabin heater is also working erratically and blows COLD air even when the engine temp goes up to 225-245.  Its really cold right now with an arctic blast driving temps here in Houston down to 18 degrees so ambient is between 18 and 32 and this is still happening.  I NEED cabin heat!!!  I cannot swallow the fact that these engines like to run hot because this just started and the heater issue came along with the engine overheating issue all at the same time.  anyone having the same problems?? 

This is certainly not what we like to hear, Russell Kutach.  Please know, customer satisfaction is extremely important to us. Our team would be more than happy to take a closer look into the concerns with your truck. To do so, please send an email to [email protected] with ATTN: Russell Kutach/GM Trucks in the subject line.

Please include your contact information, VIN, a brief description of your concern, and the name of your preferred dealership. We look forward to hearing from you. To learn more about GM’s Privacy Policy, please visit https://www.gm.com/privacy-statement.html. The information you provide may be monitored and recorded and is subject to the GM Privacy Statement.
 
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[Adam Barker]

@Russell Kutach did you ever resolve this issue? I am experiencing the same thing in my 2023 1500 AT4 

[Bikerjon]

Welcome to the forum. What engine and how many miles?

[Adam Barker]

Thank you! 

Duramax 3.0L, 23k miles

[GMCustomerService]

On 12/2/2023 at 8:51 PM, Adam Barker said:

@Russell Kutach did you ever resolve this issue? I am experiencing the same thing in my 2023 1500 AT4 

This is certainly not what we like to hear, Adam Barker.  Please know, customer satisfaction is extremely important to us. Our team would be more than happy to take a closer look into the concerns with your 2023 GMC AT4's engine temperature. To do so, please send an email to [email protected] with ATTN: Adam Barker/GM Trucks in the subject line.

Please include your contact information, VIN, a brief description of your concern, and the name of your preferred dealership. We look forward to hearing from you. To learn more about GM’s Privacy Policy, please visit https://www.gm.com/privacy-statement.html. The information you provide may be monitored and recorded and is subject to the GM Privacy Statement.
 
Privacy Statement | General Motors
Your privacy is important to General Motors. This Privacy Statement addresses the personal information GM collects and how GM handles that personal information.
www.gm.com
 

[redwngr]

On 12/2/2023 at 8:51 PM, Adam Barker said:

@Russell Kutach did you ever resolve this issue? I am experiencing the same thing in my 2023 1500 AT4 

[Russell Kutach]

On 12/11/2023 at 10:24 AM, redwngr said:

Unfortunately I totaled the truck in February but before the wreck, I had to add one whole gallon of coolant to the truck.. My thoughts?  Blown head gasket??  theres a reason that exact same engine was discontinued... had to be flawed.. and NO the temp is not supposed to fluctuate as much as mine did I dont care who says otherwise on this forum.. they dont know what they are talking about in MY situation...  Until it started acting up, the temperature never moved much at all...  sell it now!

 

[Cleveland Francois]

I'm experiencing something similar with my 2020 AT4 with 139k miles. Never had any issues before.