Hi guys,

I recently replaced the 4R55E unit in my truck with a remanufactured one and install went well and truck drives pretty good except for somethings. I've been chasing an issue with a code that keeps coming up but I am wondering what is an acceptable temperature for these units. For years I've had a Hayden trans cooler installed and the fluid no longer goes through the rad then to the cooler, it goes straight to the cooler then returned to the trans. I also have an autometer trans temp manifold and sending unit installed on the output hard line in the position where it would enter the rad before the cooler.

The reading takes some time to move up above 100 degrees F and after a few miles it settles at around 160-175F. Decided to hook my scanner up to check the reading from that for the temp and that was reading 243 deggrees F. Is this difference normal? Is my tranny cooking itself? Could I have a bad TFT sensor? Would a bad torque converter cause this much more heat? What is the ideal temp to check the fluid level and where should it be on the dip stick at that point?

Thanks

 

You don't want above 200degF unless towing and not above 210degF in that case

The radiator trans cooler is used to maintain a more consistent temp, in the 160-180degF range in colder climates
Trans cooler is located where radiator coolant temp should be at about 160degF after engine fully warms up

Hopefully the 243degF is a broken sensor, I would see what TFT sensor shows just after cold start then as trans warms up as a "sanity test"

 

I started it up cold and the temp was 85 degrees and went to 95 after a few minutes of idling in the garage. Took it for a short drive and after about 7 miles or so it was up to 160. Kept driving for another couple of miles and it went up to 190. Turned around and headed back as I pulled back into the garage it was reading 215. I used my infrared thermo and pointed to the trans pan and got a reading of 200 degrees.

Not sure if the TFT sensor is good or not but if at 243 degrees, would I have noticed anything with the shifting? I may need to invest in a bigger trans cooler and I have to check why the autometer analog gauge in the truck isn't reading more accurate or maybe that is accurate and the one in the pan isn't. Need to do some checks.

Anyone know where I can get the heat shield for the 4R55E trans from? It clips to the side of the trans over the servos and is held on with a nut. Let me know where I might get one from as the old one off the other unit got destroyed.

Thanks

 

Good article to read here: https://mechanicbase.com/transmissio...-transmission/

 

Thanks RonD, do you think if that was the true temp (243) the trans is on its way out? I will drain some fluid from the pan and see the condition. Trans just has 300 miles on it from rebuild and it was a HD clutch kit build so hopefully its fine and speed was under 50mph at that temp.

 

Just smell the dip stick fluid, you can easily tell if its starting to smell "burnt"

 

I drained a little from the pan and is still cherry red and no debri or clutch material was noticeable. Smelt fresh as well so hopefully no harm was done if that temp was indeed correct.