Duramax running temp.

Are they behind trans cooler and all I can see is small coolers like a/c.and trans
 
They would be in front of the cooling stack. Sounds like you don't have them.
 
Nop. Looking through the grill all I see is cooler radiators. I am going to check with dealer to. Thanks
 
gsmall said:
2020 3.0 duramax runs Hot. Temp gauge reads 210 to 235. Ran at 210 for first 65,000 miles and dealer doesn’t know what to do to fix it. Told me that’s the best they can do?
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What temp? Oil or trans temp. My oil runs mid 200 to 225. My trans well, I put a new larger pan, a trans bypass and a larger trans cooler. Trans temp on a 100 degree day pulling my boat might get upto 140-150. It use to be 198- 205. I'm not on here all the time. Text are welcome 325-518-4038
 
Im having the same issue, I have a 2020 chevy 1500 with the 3.0 Duramax. My temp goes above 210 and it fluctuates. The flow control valve was recently replaced along with the radiator due to a small leak but the issue persists. Since so many people are having the same issue has anyone been able to figure out what the actual fix is. I don't think is a normal thing for the temp gauge to fluctuate like that.
 
jeperez087 said:
Im having the same issue, I have a 2020 chevy 1500 with the 3.0 Duramax. My temp goes above 210 and it fluctuates. The flow control valve was recently replaced along with the radiator due to a small leak but the issue persists. Since so many people are having the same issue has anyone been able to figure out what the actual fix is. I don't think is a normal thing for the temp gauge to fluctuate like that.
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Welcome.
 
Gemarsh, I'm a DIY'er & do as much myself as possible for maintenance & repair of all my equipment. Thanks for your input on the shutters. After reading this I looked in my truck operators manual for information. I didn't see any info like the PDF image from a manual you provided. Where did you get that image? I looked on my truck & the shutters are in the open position & it's 0°F outsde & in my opinion should be closed for a warmup/startup. So I would like to read about the operation/synchronization & troubleshooting of the shutters? Any suggestions? Tell me more about the "Launch". If doing a Google search, do I search for "Launch"? Any suggestions on service/repair manuals or online subscriptions for service/repair manuals? TIA
 
Gemarsh, One more thing. The reason I'm asking these questions is I'm trying to troubleshoot my cooling fans that are running on continuous high speed operation while it's 0°F outside. See my thread about cooling fans. TIA
 
I bought the launch on Amazon.

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There isn't much info on the shutters in the OM.

Screenshot_20260115_153742_Adobe Acrobat.webp

Screenshot_20260115_153817_Adobe Acrobat.webp

With a bidirectional scanner, like the launch, you can command the shutters open and closed. If the fuse is blown or if the ecu doesn't think the shutters aren't working, it should throw a cel.

The only time I've heard of the fans running wide open when it's cool, is when the cel is on. The code usually points to the CCV (coolant control valve).

The shutters really don't control the temp, like a normal person would imagine. gm are using them for fuel mileage. They are supposed to close going down the road at highway speeds, which will eliminate with resistance. 🤬
 
Born2bwild said:
Gemarsh
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Gemarsh, Thanks for the reply & information. I'll do some more research on the shutters. This morning we had a major outside temperature increase, 38°F currently outside. Upon startup the truck engine cooling fans were operating properly, very puzzling? Any suggestions on service/repair manuals or online subscriptions for service/repair manuals?
 
gsmall said:
2020 3.0 duramax runs Hot. Temp gauge reads 210 to 235. Ran at 210 for first 65,000 miles and dealer doesn’t know what to do to fix it. Told me that’s the best they can do?
Click to expand...
Man, sorry to hear that. I have a 2023 LZ0 and my temps stays between 120 and 155 and 155 is rare. When I first bought it and saw the hi temps, I had to do something. I installed a larger PPE trans pan, trans bypass and a larger trans cooler. I have no issues. Pulling my boat here in Texas heat it might get to 140 ish
 
E.Reed said:
Man, sorry to hear that. I have a 2023 LZ0 and my temps stays between 120 and 155 and 155 is rare. When I first bought it and saw the hi temps, I had to do something. I installed a larger PPE trans pan, trans bypass and a larger trans cooler. I have no issues. Pulling my boat here in Texas heat it might get to 140 ish
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Those temperatures seem extremely low. Are you stating engine coolant temperatures, engine oil temperatures or transmission oil temperatures? If you are stating engine coolant temperatures, I would think that you have a the coolant control valve issue. I would believe coolant temperatures that low would quickly lead EGR, DPF problems leading to shortened engine life with premature engine failure.
 
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