Author Topic: Transmission Oil cooler line temperature sensor install ('06 48re) (Read 14400 times)

noplugs · « **on:** March 13, 2009, 04:43:41 am »

There is always a lot of debate as to where you measure the Transmission Oil temperaure but I decided to measure the oil temp as it comes out of the transmission. It is a better indication of the peak temp of the oil and I think gives you a better indication of how hard you are working the transmission.To measure that temp, I bought a replacement oil cooler line from Diesel Manor. It is a drop in replacement and takes about 30 minutes to install.

Tools

22 mm open ended wrench
19 mm open ended wrench
1/2 to 1 pint of trans fluid (to replace what you lost)
temperature sensor (mounted in the new replacement line)

This is the new cooler line with the T fitting  for the sensor

Here is the old line that you will replace

Have all the tools with you under the truck and be sure to put down something to catch the oil spill. As soon as you take out the old line the oil will start dribbling out of the line and the out of the transmission.

Remove the top pipe fitting
This pipe is actually connecting to the water-to-oil intercooler mounted on the engine. Fluid goes from here to the oil-to-air intercooler mounted in front of the radiator. Using the 22mm wrench, loosen the nut at the engine right above the starter motor (on the left side of the brass fitting).

Put a small rag under the open fitting to capture any oil. This also breaks any vacuum in the pipe so you don't pull oil out of the upper lines. Most of the oil should start draining into the transmission via the return line. (You can stuff the small end of a rubber glove in the hole to prevent oil from dripping out)

Remove the bottom pipe
Loosen the nut on the transmission side of the pipe. It is just above the front left side of the transmission oil pan. Get the rags ready as the oil in the tube will drain out and oil will start dribbling from the hole. Put the pipe to one side.

Install the new pipe
Grab the replacement pipe. This is the fitting you will finger tighten into the hole. (the new one will not be brass as you see here) It will be challenging since the hole doesnt come straight out of the transmission but is angled upward making it a bit tricker to get it threaded correctly. Tighten to 24 ft/lbs (verify with your service manual)

You will be tightening nut(?) into the brass fitting you see here.

You can see the angle better in this picture.

Tighten the top nut
Once that is in and tightened screw the top compression nut onto the brass fitting on the engine and hook up the temperature sensor wire. Installing the gauges is detailed in one of the other DIY's. This one also needs tightening to 24 ft/lbs (confirm with the service manual)

Now, add the 1/2 pint of oil you lost doing this. Then start the engine and put the transmission in neutral to allow the oil to circulate (keep your parking brake on) after a few minutes shut off the truck and check for leaks. If everything seem oil tight take a test drive but check for leaks periodically

Assuming the electrical work is good, you will see the temperature rise. If you really want to see the temp rise, either tow something or do a few boosted launches. 2 boosted launches should easily get the temperature up to 210 or 220 degrees.

(I take no responsibility for the testing you do on your transmission so you follow these instructions at your own risk. If you feel uncomfortable working on your transmission, please allow a professional to do the work.)