Transmission Woes

[Txcummins2013]

Hey guys, posted a few times on this but did not get a lot of responses so trying again. Have an 05 Cummins 2500 with a 48RE that was rebuilt at 97k and again at 136k now 162k. I live in Houston and daily temps are 90+ right now and my truck cools down fine until I get on the highway where my temps will go into the mid 190's at 70-75mph. Now i checked to see if my TC is locking by the 50-60 roll while looking for rpm and speed rise and or looking for a 500-700rpm when it locks and both are good so I do not believe TC is bad. I am almost positive that the trans was not flushed when rebuilt at 136k cause there was material in the pan and magnet at my last fluid and filter change. Truck shifts beautifully and cools down real well after sitting a few minutes. I have a few questions. 1)have replaced cooler and cleared thermostat at trans and check ball valve....could a clogged transducer and governor solenoid be giving false readings without throwing a code? 2) any other tests to check lockup on TC i could be missing?

 

[p-Bar]

It throws a code for the Gov pressure soleniod . Where are you tapped for your temp sensor for ? what did your rebuild involve?

 

[cerberusiam]

The temps are normal for this time of year ad the stock fluid cooling system in place. The Edge tends to read high so you are likely not that hot by a good gauge.

 

[Mathes308]

Mine won't get hot at highway speeds, especially with the converter locked. Maybe 130 max, sensor is on the line coming out of the trans before the fluid to fluid cooler.
If I sit in traffic a long time it will creep up to engine temp, about 180, but a short drive at 55mph will bring it back to 120-130
If it's getting that hot at highway locked I'd hate to see pulling or unlocked up a grade.
Killing one every 30k I would take a better look at the cooling system.
Did anyone flush or replace the engine coolant to trans cooler? Maybe it's partially blocked with debris.

 

[cerberusiam]

If I sit in traffic a long time it will creep up to engine temp, about 180, but a short drive at 55mph will bring it back to 120-130.

Either your gauge is way off or you have heavily modified the system which doesn't compare. Your temps are way low for normal temps in the typical system, especially for southern summer ambient temps. The heat exchanger will keep the fluid right at engine coolant temp of about 190 constant to the cooler. The typical cooler circuit will remove 40-50 degrees of temp then the fluid goes back thru the trans drive train to cool and lube it putting it right back into the 170-190 range in the pan which is a mix of fluid from the TC and the cooling of the drive train. Typical difference in lockup at speed is about 10% from the pan to the hot line.

Your gauge is about 40 degrees low from what it should be reading for a stock system in the cooler output line. The only way you see actual temps that low is ambient temps 0 degrees or lower and removing the heat exchanger from the system. I would not trust any readings you are seeing from that setup.