So I finally have my truck back on the road after the 4l80e swap. It runs and shifts fine. Feels 100 times better than the 4l60 ever did, and the Circle D converter locks up in od just as it should. The only thing that has me worried though is that the trans temp went as high as 230 degrees today. I have a big trans cooler with a fan on it as well. How hot do the trannies run in your trucks and what do you have on them to keep them cool? Thanks.

 

I have a 99 2500 with the 4l80e. Mine never gets that high even pulling a heavy load. It does have a stock cooler. I live in Arizona - it gets hot here. So I worry about your high temp. Did you install the guage or is it stock? Could you have the cooler lines reversed?

 

Also live in AZ, and 130s is normal temp not beating on it.

 

Jeez I need a 40k. I see 215 driving normal through Vegas.

 

I have the big 40k cooler and it stays around 140. I have it between my intercooler and radiator.

 

Mine runs 130-140 no matter what i am doing. When the filter got clogged up the temp started going way up 180ish. After i replaced the filter the temps went back to 130-140.

 

I'm using the stock guage, but I didn't think it would maske a difference if the lines were connected to the cooler one way or the other. It's got to go through the cooler anyway, right?

 

If your lines are backwards, then they are goin thru the cooler first, then thru the radiator which is goin to heat the fluid back up imstead of cooling it down.

Mine run anywhere from 110-160 DD and towing.
Either your gauge is messed up or you have a slipping problem?



What do you consider a big transmission cooler?
And why a fan? Where is it mounted?

 

My cooler is a 2 row cooler with a fan. It takes up all the space between the radiator and the grill. I dont have it connected to the radiator. I bypassed it when I did the 4l80e swap. I think that the factory gauge could be wrong. I'd have to connect another one to test it. i guess.

 

You must find the cause of the high temp.
First, determine if the fluid really is that hot. You could try and touch the tranny fluid lines with a meat thermometer, or stick it in the spaces of the tranny cooler.
Is it possible you have a restriction in the fluid flow? Maybe you could disconnect one of the lines (preferrably the return line so as to check the cooler flow too), and catch the fluid in a container for a few seconds - this will take two people. Sometimes cooling radiators have manufacturing crud in them that needs to be flushed out. It is worth a try.
But whether or not you find the cause, you do not want to drive with that kind of tranny temperature. I do not have my owners manual with me right now, but it seems to me there is a warning. If it exceeds XXX degrees, stop the vehicle and let it cool, maybe with the engine running - I do not know. Look iot up.