Reference the No 1 truck in my sig with the DTT transmission.

I have an ISS trans gauge installed in the trans line leaving the transmission going to the cooler. When I'm pulling a load up a long grade my trans gauge begins to read warmer. That's to be expected. What has always baffled me is that when I'm under load and crest the hill on my way down the trans temps continue to rise. Seems like it should be cooling down, not rising. On a long pull (like uphill from Durango to Molas Pass on the way to Silverton, CO) with my 2,200lb Lance camper in the bed I see temps around 200* until I crest the pass and then my temps shot up to around 220* or so.

With no load the trans temps on the highway barely rise above the 140* mark, sometimes up to an estimated 160* - 170*.

Just wondering why the trans temp continues to rise somewhat when I'm on my way downhill???

 

id say its the fluid thats coming out of the TC on your way down the hill its still gonna be hot for a lil bit. im no trans expert so thats just my opinion mind you. i dont know for sure jus how quickly trans fluid cycles thru a TC

 

X2
It'll take a little bit of time for the trans pump to empty the hot oil out of the heat-maker (torque converters convert diesel into heat lol) and refill it with cooler oil. Also, depending on what type of gauge you have, some of them take a bit of time to register, ie, the trans could already be that hot and the gauge just hasn't got there yet. Kind of like the fuel gauge when you fuel up. My tank's always full long before the gauge gets there....