Engine cooling issue with 6.2

[schendela]

So after reading the below thread 8 months ago, the following has occurred.

Fans run like the engine is overheating, coolant gauge reads no temperature, A/C disengaged.

Coolant Temperature Sensor. A very easy switch out and you won't lose much coolant at all if you clamp all the hoses going in/out of the waterpump next to it and the thermostat and do it when its cold. It sounds like the classic issue of the coolant temp sensor not giving any reading to ECM...

www.tahoeyukonforum.com

8 months ago I replaced the coolant temp sensor as it had gone bad. Replaced it with a generic sensor from Oriellys. A month ago, same thing happened, replaced with same part.
During that 6 months we drove probably 15k, everything was fine, except yukon would never get up to 200. Chalked it up that the thermostat was stuck open, didnt really matter to us, we live in texas and again, wasnt causing any issues.

A month ago, the sensor went out again and figured while Im elbow deep in the engine bay, Ill replace the thermostat, again with some generic thermostat from Oriellys. Drove it probably 1500 miles before I noticed one day while driving to colorado that it was getting above 220. It would get to 225 but then go back down, just enough of a difference to move the needle on the guage. For the rest of that drive (300 miles) I logged the temps/speed/engine load on my phone. All was ok. Drove it back to Texas the next day, everything was fine the entire drive (1k miles).
Then today, we were in Dallas, not paying to much attention I saw the guage move and started up the scanner, saw it was sitting at 225, but would cool back down. Well driving home from dallas I wasnt able to go above 77mph or the yukon would sit above 230. Didnt matter what I did, any load on the motor would just cause the temp to go up and slowly work its way down. 50 miles from home I stopped at a car wash to wash the radiator thinking it might be clogged up and just not have good air flow.

Got home checked the upper hose and lower hose with a temp gun, 50 degree difference, so it seems to be working, but the problem still exists.

During idol, it stays around 216, but under any engine load the temps crawl up and slowly come back down.

Does anyone have any ideas? Im to the point where im thinking about running a 160 degree thermostat, as well as buying the GM temp sensor, but not sure. I wouldnt think its an air bubble in the cooling system, since it waited almost 1500 miles to show first signs, but then didnt do anything until roughly 3500 miles (after thermostat replacement)
Now Im no mechanic by any stretch, but I understand most things, so I dont know. I dont think I bled the system out as best as I could have, but again with the mileage after changing it I would have thought it would have shown up sooner.
No codes or anything either.

That was last night on the drive home, roughly 180 miles.
Today, I have taken the top shroud off to inspect the radiator, which does appear to be dirty, but doesnt seem excessive. I have removed the upper radiator hose, and everything seems to be full of coolant. Purge tank is full as well. When I removed the cap, it leaked out, making me think that the system is at proper levels in both rad & engine.

Any ideas?

Let me know what you guys have.
Thank You!

 

[Marky Dissod]

Just thinking:
burp it again (had to burp my LT1 Caprices several times over 7 days to fully burp all air from coolant)
replace temp sensor with genuine GM
replace thermostat with genuine GM
...
does your transmission have the updated thermostat / temp control?
You may want to check your ATF temps when the coolant temp sensor reports 221F.

 

[schendela]

Just thinking:
burp it again (had to burp my LT1 Caprices several times over 7 days to fully burp all air from coolant)
replace temp sensor with genuine GM
replace thermostat with genuine GM
...
does your transmission have the updated thermostat / temp control?
You may want to check your ATF temps when the coolant temp sensor reports 221F.

I didnt think about checking trans temp during this whole ordeal. But the trans temp has always, atleast on the gauge looked like it wasnt working properly either. That is something Im going to have to look into, but I dont think my bs little scanner can look at the trans temps, atleast not live/log it.

 

[Fless]

Are you reading the engine temps with a scanner? If so, ignore what the gauge says until you know it's accurate.

We've seen many issues with the aftermarket ECT sensors; at this point it might be wise to use an OE (not "OEM") sensor.

OE = Original Equipment = what originally came with your vehicle
OEM = Original Equipment Manufacturer (who know if this mfr. made this particular part as OE?)

 

[schendela]

Are you reading the engine temps with a scanner? If so, ignore what the gauge says until you know it's accurate.

We've seen many issues with the aftermarket ECT sensors; at this point it might be wise to use an OE (not "OEM") sensor.

OE = Original Equipment = what originally came with your vehicle
OEM = Original Equipment Manufacturer (who know if this mfr. made this particular part as OE?)

Yes all temps have been read with a scanner not off the gauge.
How do you know what originally came with the vehicle? I ask as I bought this yukon at 90k. I have put two of these sensors in myself in the past 8 months. I would assume the GM genuine sensor, would be the most ideal swap at this point?

 

[Marky Dissod]

How do you know what originally came with the vehicle? I ask as I bought this yukon at 90k.
I have put two of these sensors in myself in the past 8 months.
I would assume the GM genuine sensor, would be the most ideal swap at this point?

So long as you don't buy it from scamazon, yes, GM Genuine / AC Delco / Delphi

 

[schendela]

Update,
burped the system again, seemed to have everything full like it should be. Went on a test drive, again temps raised past 230, highest it hit was 237 when I decided to just coast the vehicle for a bit to let it cool down (roughly a mile from my house). By the time I got back to my house it was sitting around 217 and then I checked the hoses with a laser therm. and temps were roughly 201 on the thermostat side and 149 on the lower hose(at inlet to water pump).
All metal like heads and things were temping at 210-220. Fans were on and blowing air. It seems to be correct, but temps still are doing "dumb things".
I have ordered a genuine temp sensor, so we will see if this is a faulty sensor or not. After that, I think it might go to a dealer/shop as Im at a loss. All things say it should be good, but Im sure Im missing something.

 

[Doubeleive]

Update,
burped the system again, seemed to have everything full like it should be. Went on a test drive, again temps raised past 230, highest it hit was 237 when I decided to just coast the vehicle for a bit to let it cool down (roughly a mile from my house). By the time I got back to my house it was sitting around 217 and then I checked the hoses with a laser therm. and temps were roughly 201 on the thermostat side and 149 on the lower hose(at inlet to water pump).
All metal like heads and things were temping at 210-220. Fans were on and blowing air. It seems to be correct, but temps still are doing "dumb things".
I have ordered a genuine temp sensor, so we will see if this is a faulty sensor or not. After that, I think it might go to a dealer/shop as Im at a loss. All things say it should be good, but Im sure Im missing something.

we are seeing multiple multiple reports of these presumably aftermarket sensors and thermostats being bad out of the box or within a short period afterwards.
particularly on the K2xx (2015-2020)
I would def recomend original from dealer or legit retailer.
just keeps coming up almost weekly....... and like you people are replacing them again and getting the same results -failure

 

[Fless]

Use one of the online GM parts sites -- gmpartsgiant, gmpartsdirect, etc. Enter your VIN and you can find the OE part numbers for purchase there or for searching other parts places.

Like this (but that may not be your SUV): https://www.gmpartsgiant.com/parts-...front_cover_cooling.html?filter=(e=L86;t=MYC)

 

[schendela]

Use one of the online GM parts sites -- gmpartsgiant, gmpartsdirect, etc. Enter your VIN and you can find the OE part numbers for purchase there or for searching other parts places.

Like this (but that may not be your SUV): https://www.gmpartsgiant.com/parts-...front_cover_cooling.html?filter=(e=L86;t=MYC)

This seems to be of concern, the thermostat is discontinued. Im sure that is just that model for some reason, but still strange to see discontinued on a thermostat.

 

[Marky Dissod]

Strictly regarding thermostats / thermostat assemblies, I'm willing to trust Gates, Stant, and/or MotoRad -
unless new info comes to light to convince me to distrust them ...

 

[Doubeleive]

View attachment 424519
This seems to be of concern, the thermostat is discontinued. Im sure that is just that model for some reason, but still strange to see discontinued on a thermostat.

gm changes part numbers like women change clothes, superseded
Superseded Part Number
12674639 GM12671393 12666569 12650534 12671393 12650536
those may be old as well
best thing to do is call your local dealer parts department and give them the last 8 of your vin and they can tell you the current part number.
if they won't give it to you, then hang up and call ANY other gm dealer parts department, some are dicks

 

[Doubeleive]

you can also enter it on the ac delco website and search there, it has the option to enter your vin or year/make/model.

https://parts-catalog.acdelco.com/acesCat.php

 

[Doubeleive]

View attachment 424519
This seems to be of concern, the thermostat is discontinued. Im sure that is just that model for some reason, but still strange to see discontinued on a thermostat.

after a little searching it appears that is the correct part number, but I don't think it is discontinued there just isn't any in stock OR they are in the process of changing part numbers
there appear to be some around online....
ac delco list's the same part number
and autonation list's the same part number and autonation is a HUGE gm parts dealer
this part is good for 2015-2020 6.2l gm isn't going to stop making parts for vehicles that are still under warranty, so somethings up

 

[schendela]

Update. Went and put in a new GM thermostat and that seems to have corrected the problem. On a 20 mile drive doing 80mph, the temp never went above 200. I let the yukon idol for 30 minutes and it sat at 216 the whole time. Started driving again and back down to 190s. So problem solved for now. Im going to wait for the temp sensor to fail again and go with a GM part for that as well.
Lesson learned, for the family daily vehicle, go OEM.

 

[Joseph Garcia]

Update. Went and put in a new GM thermostat and that seems to have corrected the problem. On a 20 mile drive doing 80mph, the temp never went above 200. I let the yukon idol for 30 minutes and it sat at 216 the whole time. Started driving again and back down to 190s. So problem solved for now. Im going to wait for the temp sensor to fail again and go with a GM part for that as well.
Lesson learned, for the family daily vehicle, go OEM.

Good lesson learned. You get what you pay for, at best.

 

[mattbta]

For future reference, partscenterplus on eBay is a GM dealer in AZ with reasonable prices and quick shipping. I use them whenever I need guaranteed OE parts.

 

[Bagherra]

I'm havin a hard time finding an OEM thermostat as well....
AC Delco15-1125...everyone is "Unavailable" or "Out of Stock"

 

[Doubeleive]

For future reference, partscenterplus on eBay is a GM dealer in AZ with reasonable prices and quick shipping. I use them whenever I need guaranteed OE parts.

pretty sure that is autonation also

 

[West 1]

Gates makes thermostats and I have used them several times with success.
Stant is another brand I use and trust for thermostats.