Hey guys. I recently put a tranny temp guge in my truck and installed the sensor right before my cooler. Its not giving me satisfactory readings whatsoever. 75% of the time, it says the fluid is 100* and has never read 160*... So I wish to install it directly onto the side of the tranny. My question is: which line is the feed and which is the return? I figure the "out" is the bottom one because its gotta suck fluid from the bottom, then cool it and return the fluid to the top of the tranny to trickle down onto tranny components. I could be wrong though. Also, does nayone know the size of the threads on the tranny lines? I need to know if I need adapters and such and I have no way of measuring them. Thanks guys!

 

One quick way I found which tranny line is output from the tranny to cooler. With truck cold start engine and put it in gear. Hold the brake and powered up to the torque converter's stall speed for 20 seconds. Then shut off engine and go feel which line is hotter than the other. The hotter line from the tranny is the output line to the tranny cooler.

With engine at stall speed of torque converter, the fluid will get hot really fast so don't over do it or you could burn up the tranny. Also block the wheels as you could over power your brakes too.

 

Hmm good thinkin! Ill give that a try for sure!

 

The line that goes to the back of the transmission is the return line.
But you do not want to put a temp sensor on the cooler lines anyway. All you will read is the TC temp and not the transmission temp.
The only place to put the sensor is in the test port on the drivers side just above the pan.
Unless you just like to see high temp readings.



/