2008 Chevy Silverado 5.3l with Automatic Transmission (high trans temps)

[Imnotlikeyou]

Hello,
I have a 2008 Chevy Silverado with a 5.3 l engine. The engine is remanufactured/new. The transmission is also remanufactured/new. The transmission fluid is obviously also new. I have also installed a transmission cooler which is twice the size of the original cooler.
I have also installed a switch controlling the 2 cooling fans.
So, I am seeing transmission temperatures that I have allowed to reach as high as 215 degrees (before pulling vehicle over and allowing it to cool).
Based on my research, supposedly there is a transmission thermostat that is attached to the top of the transmission with the two cooler lines attached to it.
I have a two-part question:
What is the transmission temperature range?
Why (despite my efforts) is my transmission temperature reaching 215 degrees?

 

[zora]

Recommended you read the link below, 215 does not appear to be an issue, you dont mention air temperature.

Transmission temp? : Transmission/Drivetrain

What’s considered too hot? 14 Silverado - So while idling in 87 degree weather in traffic on a mountain pass I noticed my transmission fluid temperature got up 212 degrees ...

www.silveradosierra.com

 

[Imnotlikeyou]

Zora,

I'm never before been one to post questions in forums.

As pertaining to my original post, the air temperature was 90° Fahrenheit.

I came here to Chevy forum in search of a straight honest answer because it seems that the internet is flooded with all types of answers with regards to a transmission temperature range.

It's good to read that my transmission temperature is well below the 270 degree peak.

Thank you for your time.

Thank you for the link/info.

 

[zora]

Another consideration is do you have the correct engine thermostat?
See the NAPA listing

https://www.napaonline.com/en/search?input-q=5.3+L+325+CID+V8&q=N%3D2500005%2B2600501%2B2801935%2B10200800%2B5001200%2B5001400%2B200140620%2B401401900%2B599999900%26Nty%3D1%26Score%3D0.59&text=thermostat&keywordInput=thermostat&referer=nol-veh-conds

 

[Imnotlikeyou]

Another consideration is do you have the correct engine thermostat?
See the NAPA listing

https://www.napaonline.com/en/search?input-q=5.3+L+325+CID+V8&q=N%3D2500005%2B2600501%2B2801935%2B10200800%2B5001200%2B5001400%2B200140620%2B401401900%2B599999900%26Nty%3D1%26Score%3D0.59&text=thermostat&keywordInput=thermostat&referer=nol-veh-conds

I do have a (correct) new thermostat that I had purchased a while back in case I had ever needed one.
I will replace the thermostat. I'll respond once I've done that, and give an update.
Thank you for the thought.

 

[Imnotlikeyou]

Zora,

I did change the thermostat.
I installed a 190° thermostat made by Gates.
Driving today, and my transmission temperature has yet to exceed 187 degrees.
In fact, I'm seeing a temperature of about 171 to 175 as I'm driving!
The air temperature is now 72 degrees and I am towing 12 foot trailer

 

[Imnotlikeyou]

Thank you for the idea of changing the thermostat.

 

[zora]

Glad to hear that worked out for you and Gates was a good choice.