48RE / heater or cooler or both

[softailer]

I have a 2003 2500 HD / SO with a 48RE. I would appreciate some help understanding the system. Does the 48RE have both a heat exchanger on the engine to heat the transmission fluid and an air to fluid cooler in the grill also??? Are they thermostatically controlled? What is the flow circuit? Needing a little education on what I have!!! Can you please give some guidance??? SOFTAILER

 

[Bob4x4]

The water to oil heat exchanger will do both add heat and remove heat depending on engine and transmission temp. The front cooler will remove heat.



The transmission oil is routed through the main cooler first, then the auxiliary cooler where additional heat is removed from the transmission oil before returning to the transmission. The auxiliary cooler has an internal thermostat that controls fluid flow through the cooler. When the transmission fluid is cold (less then operating temperature), the fluid is routed through the cooler bypass. When the transmission fluid reaches operating temperatures and above, the thermostat closes off the bypass allowing fluid flow through the cooler.



(the front cooler is considered the aux cooler)

 

[Steakman1003]

Hi fellow Cummins owners. I am new to site. I have a 2007 early 2500 5. 9 with 48RE trans with 60k on it. I have bullydog tuner so I have trans temp guage. It seems to run at 175 degrees even in cold weather without pulling anything. I am having problems with transmission shifting thru the gears when I try to give it some reasonable pedal. I have read a few posts and it seems the Transducer and govenor solenoid need replacing on a lot of them BUT, I have no codes coming up in it at all. It seems when I give it light pedal, it seems to work most of the time ok. When I give it some decent pedal or cause it too downshift, it sticks in 2nd or 3rd gear until I let off on pedal. The warmer it gets, the more it happens. I was going to have the solenoid and transducer replaced but trans shop seems to think it is not the problem without a code coming up. Could it be my Electronic Pedal/throttle control on floor? Looking for help b4 I toss 275. 00 on solenoid and transducer.

Thanks! Mike from New England

 

[BDaugherty]

Looking for help b4 I toss 275. 00 on solenoid and transducer.
Thanks! Mike from New England

I'm not a trans expert, but I would surely change the governor pressure transducer and solenoid along with a band adjustment as a starting point for shifting problems.
However, have you let someone from the trans shop drive your truck? What size tires do you have? When you add power or change gearing, it messes with the stock shift points. I would want to test drive it before giving further advice.
Depending on your level of mechanical competence, you can easily service your own transmission, swap the transducer and solenoid, and adjust the bands. The hardest part of it all is getting the fluid level right when you're done.

 

[Steakman1003]

Thanks for quick response. I have wider Keystone rims and tires on it. I bought it that way. I am not sure if they are taller than stock ones though. 20" I think. I was the one that put the Bullydog tuner in it although I made sure NOT to say ok to "Add Low End Power" to it as it was a stock transmission as far as I know. I uninstalled the Bullydog back to stock and it did nothing to change shift issue in trans. It does have Airaid intake and JetlIne 4. 5 exhaust on it also when I bought it this spring. So i suspect original owner had it pumped up too! I bought from a used truck guy who did not know how to reach original owner so I can't really find history on vehicle. I am heading for trans guy this morning. I will make sure I ask him to drive it and have him put in the solenoid and transducer.
Point of interest..... I only have towed one car trailer since I bought it. It was a UHaul aluminum with a 1979 BlackBird Sunbird car with no engine and trans in it. Maybe 3000 lbs... . I remember the Bullydog "Shutting down" the "Tow power setting" to "No Power" on motor as the trans temp guage went to 215 degrees on a 70 degree day. Found it odd for such litle weight behind it. Maybe my checkball valve in trans cooler line is pugged or stuck? Does anyone know what normal operating temp of trans fluid should be? I also notice that when guage says 180-190 degrees, I take the dip stick out and it feels like it is way cooler like luke warm at best. It can't be 175 degrees like Bullydog is telling me? Cooler line is pretty warm to touch at same time. We will find out more this morning!
Thanks again for helpful info! 15 degrees in New England this morning!

 

[BDaugherty]

Even though we hijacked another thread



it does sound like you have problems. 215 is not too warm for the trans. Can you adjust your warning? Where is the temp sensor located?

Where are you located? You need to fill out your profile.

Also, read the post about oil flow in the cooler circuit. 180-190 is pretty normal. You don't want it to run too cool.

 

[cerberusiam]

Operating range for the transmission fluid is 140-240 degrees, inside that is considered normal. As a rule, 185-190 cruisng in lockup is normal with the ambient temps over 70 degrees. When the temp starts dropping so does the trans temp at 0 degress a temp of 150 is not unusual.

If you using the Bulldog to read the trans tmep that is coming from the pan from the transducer I reccommend changing in your other post. The transducer is finiscky and it will read wrong and throw all manner of issues into things when it goes bad, including higher than normal temp readings and flashing light son the dash.

A temp of 215 is not unusual depending on how you were driving at the time. If it was going down the road in lockup at speed then it is a problem, it that was in slow speed stop and go traffic then it is normal. When you look at trans temp you have to take into account what you are doing and how the truck is being driven for it to make sense.