I finished my installation of a transmission temperature sensor this morning. It's on the feed line BEFORE the radiator and cooler. Problem is I have no idea what temperature is too hot.

What temps should be normal and what is too hot?

2000 xj 4.0 aw4

 

Drive around and see where it's at. That's normal driving.

 

Then what is too hot

 

Good question and I've wondered the same. The stock design pumps ATF into the radiator in tanks on the sides that separate it from the coolant. In theory, if you start your XJ and let it warm up, the idling temp of your ATF will eventually get to 210°F, or whatever the idling temp of you coolant is. Aftermarket coolers drop the temperature some more, but I know you also don't want to run too cool. With bigger tires, weight, etc. it seemed like at 210° my trans temp would climb to 230° pretty quick, so with an aftermarket cooler I've managed to stay within the range of 180° to 200°. Judging by the fluid condition during changes at regular intervals 30k miles later, I think that's a comfortable range for the AW4. 260°F and up is where it'll probably start taking damage.

 

I think you want it as cool as possible... heat kills. Ideally you want it 210 or less, but it wont hurt running hotter.. you just wont get as much wear out of the trans running hotter.

 

Try Googling it. Can't find a frickin thing!!

 

Yeah, I bet you can't...googling something like "atf max temp" will most certainly not bring up any results whatsoever.