Automatic transmission - how hot is too hot?

[TerryMason]

I've finished installing my automatic transmission gauge, and it turned out pretty well (I'll do a writeup shortly). I've driven around a bit, and the highest temperature I've seen is 155. I read somewhere that 180 is normal, but I'm wondering what is too hot? At what temp would you park the jeep and let it cool down?

 

[SteelHeadz]

Which Transmission do you have?. from my Knowlege, a Nag Transmission found on the Dodge Charger will Run up to 230 Degrees and is still considered normal. i Have not really looked into the variations of automatic Transmissions with their respective Temperature Tolerance on Min. And Max. Temp.. so if you tell me what Type of trans. you have i will do some reasearch on it.

 

[TerryMason]

I've got a 4-Speed 42RLE automatic transmission. I've done a bit of reading this morning, and most people say that the tolerances of the ATF itself is more important (which makes sense).

I read that ATF is designed for 175F and will last 100,000 miles, and that every 20 degrees above 175F the life of the fluid is cut in half. I'm not sure how accurate that is though.

 

[Utah_jeepster]

140-170 is normal operating temperature. I thought anything over 150 reduced the life of the ATF fluid though

 

[TerryMason]

I hit 155 on a brisk November morning going up the parking garage ramp, so I can't imagine what towing a boat or off-roading in July is going to do.

I've got the cooler to install, I just wanted to drive around and get a feel for what's normal, so that I can see how effective my cooler is.

 

[SteelHeadz]

Ok Mr. Terry here's the info i got from the "insider". 260 deg. is an overheat condition for most of the Chrysler Transmission including The Wrangler Trans. 180- 210 is about the Average operating Temperature. you can never overcool a Transmission so with that in mind, it would Be Beneficial with a Cooler during offroading and towing. i hope this helped you. sorry i talk a lot.

 

[TerryMason]

Hey, thanks for the info!

Do you have some sort of mole on the inside?

 

[SteelHeadz]

They are my Instructors. they're the good guys. i'm just the Fly on the wall. --

 

[Bounty__Hunter]

A cooler is a great idea, between the radiator output and transmission input. A deep transmission pan is also a good investment.

A handy mod is to use two temp sensors on your transmission, one for hot fluid out and one for cool fluid in. You can use 1 guage and a toggle switch to select which sending unit.

 

[Bounty__Hunter]

 

[TerryMason]

I don't believe that they make deeper transmission pans for my transmission (42RLE I believe), so I had to stick with the stock one.

That two sender idea is pretty slick Bounty