194 vs 207 Thermostat

[reardiff]

Looks like I'm in need of a new thermostat (won't get above 180/185 degrees). I know there's lots of post on thermostats, but one question I can't find an answer to is 194 vs 207.  I prefer to go with OE / AD Delco, based off what I've seen on different forums, but there's two options and can't seem to find which one is a direct replacement, or why there are even two to pick from?  It's for a 2017 Sierra with the 6.2.  Appreciate any insight anyone may have.

[mikeyk101]

I believe the 6.2 uses the same thermostat as the 5.3 motor. The 207⁰ thermostat is the OEM for these. There isn't a 194⁰ optional thermostat listed for Silverado or Sierra. 

 

However, saying this, there is a GM 194⁰ thermostat that does work and that's what I did on my 2016 Silverado 5.3. The particular thermostat is listed for the 6.2L motors in several years of Corvettes, Cadillac CTS, and Camaros. The part # is 12674634 but is also listed as 15-11113. It is a direct replacement and the one I am using. I highly recommend making sure it is a genuine OEM. 

 

When my OEM thermostat was failing 2 years ago, I originally tried a Motorad 194⁰ thermostat and that failed within a couple months. I changed to the 12674634 and it's been fine ever since. 

[richard wysong]

What are you trying to fix going hotter?

[newdude]

Sports cars use the 194F thermostat, p/n 12674634.  So Corvette with LT1 and LT4 (2014-2019), Camaro with LT1 and LT4 (2016-2024) and CTS-V and CT5-V Blackwing with LT4.  

 

Trucks use the 207F thermostat, 12674639 with L83 and L86 V8s 2014-2019.

Edited January 21, 2025 by newdude

[mikeyk101]

6 minutes ago, richard wysong said:

What are you trying to fix going hotter?

It doesn't run hotter, it actually runs cooler. The 194⁰ thermostat opens earlier than the 207⁰ stock thermostat and gets coolant flowing into the radiator sooner. It's a benefit especially if towing trailers. 

[mikeyk101]

Just wanted to add, not sure how you are checking on the coolant temperature. I know on my 2016 Silverado, there is a coolant temp gauge that shows 160, several hash marks and then 210. This gauge is not very accurate. when the needle is resting on the 210, the actual coolant temperature will be somewhere between 185 and 220 or so. If it dips slightly down from 210, then it is already below 185. So if you are gauging your 185 temp by using the longer hash mark in between the 210 and 160, I can tell you that it is definitely less than 185. I know this because I also have a BAFX Bluetooth OBDII module and use Torque Pro app on my phone to monitor things like outside temp, intake temp, coolant temp, oil temp, trans temp, voltage, etc. 

 

Today, I had to do a 55 mile run one way and outside temps were hovering around 0. it did take a little while for coolant to warm up but stayed right in the 185 range while rolling down the highway and that was perfect to keep the cab temperatures very comfortable. once it was warm enough, I had the dash heat set in the lower 70's and was very comfortable. sometimes while sitting at a red light, it might drop to upper 170 range but would jump right back up to 185 once I began rolling again.  

 

So I guess my point is, if you are checking the coolant temp by looking at the dash gauge and determining a 185 temp, it is actually well below 185. 

[reardiff]

Thanks for the replies. As always very helpful. Is there a difference between and  1511125? They seem the same except 12674639 is the GM# and 1151125 is the ACDelco #? Neither mention the opening temp in the description but assuming both are 207.  

 

Regarding temp reading, yes I’m going off the hash marks on the gage, although using an OBDII modules sounds like a much better way to get a more accurate reading. Any recommendations on those? Don’t need anything fancy, but something that can monitor things like coolant and trans temp would be nice when trying to trouble shoot things like this. 

[mikeyk101]

You are correct and one is GM and one is ACDelco but they are identical. And yes, both are 207⁰ thermostats. I just highly recommend using an OEM over aftermarket after my experience and reading similar experiences of others.

 

As far as the OBDII readers, the one I have been using for a couple years is a BAFX one I bought on Amazon for around $25. It allows me to also scan for most common codes as well as clear them. I am using an app called Torque Pro to monitor the functions. There is a Torque lite too I believe but I paid the fee dollars to get the Pro version. Here is a list of compatible readers for the Torque app.

 

https://wiki.torque-bhp.com/view/Bluetooth_Adapters

 

IMHO, for what I need, I didn't need one that was hundreds of dollars and there are quite a few for less than $50 which would work just fine. In my case, I also use a splitter cable plugged into the OBDII port so I can run the OBDII device along with my Range AFM disabler. Occasionally the OBDII device will fail to link up to my phone and all I have to do is unplug it from the port and plug it back in again, no big deal. This will happen sometimes if I leave it plugged in and don't drive for a couple days. 

 

 

[reardiff]

Turns out P/N 12674639 is unavailable just about everywhere. Ended up finding one on-line from a GM Dealer in TX, but they said that part was unavailable and cancelled the order.  So now I go searching for 1151125, which is out or stock also at most places also but supposedly found one on Rock Auto that should ship today - we'll see.

 

Can someone confirm that 1151125 is indeed 207 the correct ACDelco replacement?  On Rock Autos website is confusing, it says opening temp 100 Degrees C (212 F), and then down further says start to open temp 194.  Then they also have 1511125G. They both seem the same as far as I can tell. Not sure what the difference is but it's $12 cheaper. 

 

 

[mikeyk101]

I think the 100c is a mistake on their part. Everywhere else, the 15-11125 shows it as being a 207⁰/90c thermostat. I think we may need @newdude for official verification. As far as the 15-11125G, I have no idea. It is an unusual part number that I hadn't seen before.

Edited January 29, 2025 by mikeyk101

[newdude]

8 hours ago, reardiff said:

Turns out P/N 12674639 is unavailable just about everywhere. Ended up finding one on-line from a GM Dealer in TX, but they said that part was unavailable and cancelled the order.  So now I go searching for 1151125, which is out or stock also at most places also but supposedly found one on Rock Auto that should ship today - we'll see.

 

Can someone confirm that 1151125 is indeed 207 the correct ACDelco replacement?  On Rock Autos website is confusing, it says opening temp 100 Degrees C (212 F), and then down further says start to open temp 194.  Then they also have 1511125G. They both seem the same as far as I can tell. Not sure what the difference is but it's $12 cheaper. 

 

 

 

 

12674639/15-51125 is the 207F thermostat.  19474058/15-51125G is the ACDelco Gold/Professional line and is also 207F.  12674634/15-11113 is the 194F thermostat.

 

ACDelco Gold/Professional line are not the OEM part/supplier typically, they are made by one of the major aftermarket suppliers. 

 

So lets pretend that Motorad is the supplier to GM for the OEM one and build 12674639 to GM OEM specs, the ACDelco Gold/Professional one is supplied by Stant and is built to spec but might use cheaper components or alternative materials, etc.  Same with brake pads.  The OEM ones are made from the OEM suppliers (TRW, Akebono, etc.) but the ACDelco Gold and Silver line are all made by what was the Affinia's Global Brake division which is now spun off to Frist Brands Group.  ACDelco Gold and Silver all all the same as Raybestos brakes.    

 

 

 

 

Edited January 29, 2025 by newdude

[CamGTP]

I've run a Napa thermostat for years, good enough for me and they have decent warranty.

 

OEM parts can be hard to find it seems.

[steelerdude15]

3 hours ago, newdude said:

 

 

12674639/15-51125 is the 207F thermostat.  19474058/15-51125G is the ACDelco Gold/Professional line and is also 207F.  12674634/15-11113 is the 194F thermostat.

 

ACDelco Gold/Professional line are not the OEM part/supplier typically, they are made by one of the major aftermarket suppliers. 

 

So lets pretend that Motorad is the supplier to GM for the OEM one and build 12674639 to GM OEM specs, the ACDelco Gold/Professional one is supplied by Stant and is built to spec but might use cheaper components or alternative materials, etc.  Same with brake pads.  The OEM ones are made from the OEM suppliers (TRW, Akebono, etc.) but the ACDelco Gold and Silver line are all made by what was the Affinia's Global Brake division which is now spun off to Frist Brands Group.  ACDelco Gold and Silver all all the same as Raybestos brakes.    

 

 

 

 

Will the Gold brake pads last as long as OEM and stop the truck as well?

[mikeyk101]

Back in 2023, I installed AC Delco Gold rotors but stupidly chose to install O'Reilly brake pads. First ones were too wide and would bind and drag on rotors. I returned those under warranty and the O'Reilly replacements although a little better still were too wide so would bind and dragged on rotors. I then picked up a set of AC Delco Silver pads and they have worked just fine ever since. 

 

And thank you @newdude for that info. I always thought that Gold, Silver, and professional were just an upgrade from the OEM. Now I know.

[steelerdude15]

1 hour ago, mikeyk101 said:

Back in 2023, I installed AC Delco Gold rotors but stupidly chose to install O'Reilly brake pads. First ones were too wide and would bind and drag on rotors. I returned those under warranty and the O'Reilly replacements although a little better still were too wide so would bind and dragged on rotors. I then picked up a set of AC Delco Silver pads and they have worked just fine ever since. 

 

And thank you @newdude for that info. I always thought that Gold, Silver, and professional were just an upgrade from the OEM. Now I know.

The different levels of parts are listed on GM’s parts website. Here is their description: