It seems obvious that it should be about the same as coolant temp but just want to make sure. Mine was reading 205f when the coolant was reading 190. Seemed high to me.

 

I would say thats ok but wouldnt let it get to much higher

 

I had my transmission rebuilt after I burned up the clutch plates by towing 2,200 lbs of sailboat and trailer for several years. I had a transmission cooler installed and I installed an OBDII real-time gauge system to monitor the transmission temperature.

Not towing during the summer I'm pretty sure the transmission temperature would normally run at no higher than 180'F. However, after the solar eclipse in August I was drying across central Oregon through the John Day R. country (with lots of hills and one good pass) I saw that my transmission temperature touching 200'F. That is the maximum temperature below which I try to keep it.

In the fall while driving around on not so hilly places the trans temperatures would be more in the 160'F range I think.

Here is one of many references regarding the range of temperatures for automatic transmissions: Prepare the 4L60E transmission In Your S10 Blazer For Towing

"Ideally, your 4L60E should not operate at temperatures over 200 degrees. It is a widely held belief that for every 20 degrees you go above this limit, you reduce the transmission’s lifespan by a factor of two. Another important fact you might want to keep in mind is that at temperatures as low as 240 degrees, your organic oil based transmission fluid can start to turn to varnish. Once this process occurs, the total failure of your 4L60E is just around the corner."

 

Very good and thank you. I've been watching it with Dash Command. Kinda scared me the other night when it was 205f but then again I was in stop abd go mode around town.

 

If it bothers you you should get a trans cooler, easy and cheap

 

Oh yes, good insurance to have! I wish I had done that when I first got mine.

 

My trans shop even suggests adding an additional trans oil cooler after the heat exchanger in the radiator. He said that the cooler the better and that with a heat exchanger the temp would be in the 150 F range which would be just nice to the transmission.

 

+ or - 150* is ideal by factory specs, too low of temps fluid does not flow as needed, Too high of temps fluid looses viscosity and lubrication values ending with clutch slippage and burning

 

That sounds like my next project. Is there a write up on it?

 

I forget the details but I do know that not all coolers are as effective as others. Also, monitor the transmission fluid temperature routinely. I use the Ultragauge OBDII reader.