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Trans Getting Warm - Please Advise

3K views 18 replies 9 participants last post by  CatGenTech 
#1 ·
Gentlemen,

I will try to keep this from being overly wordy however please bear with me as I want to make sure I thoroughly explain what I have been seeing and what I have tried.

In 2015 I had my trans build by Firepunk. I got their street/track trans which does have a lower stall tighter converter in it. This summer I have been experiencing what I feel is a high transmission temperature problem. If I am operating at slow speeds as in stop light to stop light or heavy slow traffic or idling in drive for an extended period of time my transmission temperature will climb. I have seen it get as high as 228F while waiting in a longer line. Coolant temperature does also rise along with the trans temperature and it rose to about 208F when I saw trans temp get to 228F however I believe it to be more a result of trans temp driving it up.

I have been dropping it into Neutral if I am at a longer light or if I have to idle for any period of time and this definitely helps keep temp down. Also if I am driving at road speeds of 45mph or faster temps are just fine.. Coolant temp about 190-195F.. Trans temp 167-185F.

I felt like I have got an air flow problem so I investigated the following..

- Removed the charge air cooler and blew it out as well as engine radiator and all coolers (they were not really dirty just felt a good place to start.. did not notice any change)

- Removed and cleaned the thermostat from the trans cooler. The rod was not stuck and no signs of debris found when doing this (noticed no change after this)

- Tested the fan clutch as described in factory service manual by spooning into and grounding pin 4 on the fan clutch connector. The fan clutch did seem to lock up and seemed to be moving a lot of air when I raised engine speed. I did not have a phototach with me to verify engine speed but I can confirm it did increase and decrease fan speed when grounded and ungrounded.

- I connected my fluke meter to pin 4 and monitored my voltage reading and duty cycle while I forced both coolant and trans temps up by placing coardboard in front of the radiator between the trans cooler and radiator. Placed the truck in gear and standing on the brake. When coolant temp reached 212F I observed the meter reading go from 14vdc to 12vdc and duty cycle go to 85% then to 100% and the fan did lock up and coolant temp started to drop to about 208 then kicked off. I let trans temp climb to about 238. Removed the cardboard and coolant temp dropped pretty quick but the fan didn’t stay engaged. I re-grounded the fan clutch manually to force it back on and help cool trans temps down.
I thought I had a failed fan clutch giving me troubles but I feel I can rule that out now so hopefully I can get some questions answered and some direction..
1 – Are these temps cause for concern? Am I just being paranoid? This is not a drag truck or competition truck.. If I was using it as a fully build truck and sitting on the line staging or had a truck built for these purposes I wouldn’t be that concerned.
2 – Is the truck supposed to be turning the fan on to control temps at a lower temp? Does it engauge the fan based on trans temp?
3 – I am wondering if I just need to invest in a aux cooler setup under the bed?

Any advice would be appreciated. Thanks
 
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#2 ·
I am looking at an hp tuners file and it looks like the fans should kick on based on trans temp. It shows a trans temp of 232* as the threshold to kick the fan speed up. Are you readng the trans temp via obd port? Is the heat exchanger on the block still connected?

If you can graph both trans temp and coolant temp via the obd port data you might see which could be causing the problem. Meaning graphed data would show one rising before the other when the issue starts
 
#3 ·
Yes the trans and coolant temp are being read via obd2 on my insight.

I will look and see if i can use either my insight or efi tuning tool to log the temps and display them using a graph.

I am really leaning toward trans temp being the one forcing the other up. I can watch trans temp rise over time. When it reaches close to or equal coolant temp coolant temp will start to rise as well. Trans temp will rise beyond and faster then coolant temp.
 
#5 ·
Yes the trans and coolant temp are being read via obd2 on my insight.

I will look and see if i can use either my insight or efi tuning tool to log the temps and display them using a graph.

I am really leaning toward trans temp being the one forcing the other up. I can watch trans temp rise over time. When it reaches close to or equal coolant temp coolant temp will start to rise as well. Trans temp will rise beyond and faster then coolant temp.
No need to log & graph, that answers it right there. I ditched my AT a couple of years back but from what I remember, trans temps never rose on mine. I did have the +4qt deep pan and had the block exchanger bypassed though.


forgot to mention... I used to have a 2nd cooler under the cab with a fan on it. never did hook the fan up, never needed to. Highest trans temps (measured in the pan) was 185*f. North Dakota??? could high humidity be causing any issues with cooling?

Hopefully someone else can add in here soon.
 
#4 ·
When i get home shortly i am going to try measuring and recording the delta temp across the radiator and trans cooler as well as pan temp and see what they look like
 
#6 · (Edited)
Yep your right its answered already then. From what i recall the first summer after i had the trans built i didnt haave the issue with temps rising like that. I do have a deep sump pan. The block exhanger is still in thers as it gets pretty cold here in tbe winter.. Do you know temp differential spec across the trans cooler?

Also i should add that i moved to Illinois May 2015. Last summer i dont recall being as hot and humid as this summer has been. And high humidity was a thought i had also but i didnt know how much it would effect things.
 
#7 ·
My trans guy that built mine said don't worry about that temp. The edge reads the highest point and it's not a big deal. I've seen that temp in winter pushing snow. 230-235 is my personal limit.
Most of the time mine is about 210 anyway. FYI, the B&M 10280 only adds a few qts. NOT what they state. Still worth the $ just for the drain and extra fluid and fins.
Now with all that said, I plan on putting on a extra cooler and filter once the warranted is up.
 
#8 ·
Well first of all thank you for the information here it serves to confirm my testing that I just completed.

I have talked to my builder and they did tell me the transmission will generate a lot of heat when it is in gear and in fluid coupling mode and not locked and that it will drive the trans temp up when not moving down the road until the TCC locks. I didn't think to ask what a safe upper limit to temp was however.

I decided to force the temperature up and monitor it while it climbed to see if it would level off or just continue to climb out of control. I placed the truck in gear with the park brake set. TC outlet temp climbed pretty quick and once it reached coolant temp both coolant temp and trans temp started coming up. Above 200F trans temp was rising quicker then coolant temp. I let it continue to rise to see what would happen. Once temps reached Trans 232F/Coolant 207F the fan clutch engaged for about 5 seconds. Coolant temp dropped quickly to 186F and trans dropped to about 205F. Temps rose back up again over time till the clutch kicked in and dropped temps again.

I have done a LOT of digging attempting to find the actual temps that the ECM turns the fan clutch on and i seem to have found that at 212F coolant temp and 232F trans temp it engages so hopefully someone else may benefit from that...

I guess now i just need to think about an aux cooler because it is still warmer then i like but i guess i can feel better about weather or not the cooling system is working or not.
 
#9 ·
Did you ever put a cooler in? If so what did you go with and where did you locate it. Mine also gets rather warm while hunting. Driving through fields climbing hills and only ever going around 30km/h tends to get that oil hot quick. I wonder if a guy could just tap a wire into that pin 4 on the fan and run it ti a switch then to a ground and manually lock the fan clutch???
 
#10 ·
I've been trying to figure out how to appropriately wire that switch up for a year now. I have asked for someone that is better at electronics than me to post a write up showing how to do it. Best I can gather, you will need a three way switch, one way will be the normal path thru pin 4 to ecm/TIPM, and the other way will be directly to ground. I just hate to start cutting into my trucks harness unless ok ow exactly what I'm getting into beforehand. I have also thoughts about wiring in a resistor to water temp or trans temp if that is easier to force the ecm to lock the fan up, but I don't want it to cause the truck to defuel or change the trans logic because it thinks it's too hot. I just really want to flip a switch and lock the fan up. Period. Every over the road truck I drive has the ability to do this, and I use it all the time. Better to keep temps in check instead of trying to get them back down once they go up.
 
#13 ·
Tap into the clutch side of the wiring and leave the truck side alone. On your '05, this will set a soft code but shohld not set the CE light.


- Tested the fan clutch as described in factory service manual by spooning into and grounding pin 4 on the fan clutch connector. The fan clutch did seem to lock up and seemed to be moving a lot of air when I raised engine speed.
 
#11 ·
Don't forget you could be just seeing the normal operating temp... if the fan is programed to kick on at 230 or so, there is a reason they chose that temp.
 
#14 ·
HP Tuners has it speeding up the fan @ 232*f trans temp and full speed at 240*f. CTs its 210*f.
 
#17 ·
2004...... My experience with a built 48re is this. Trans runs hotter. It will rise in heavy traffic on a hot day. I have seen bursts to 280-300. But this is important... my sensor is on the fluid exit line of the TC. This is the place where the oil is at it's hottest. I route it to a fan cooled aux cooler before it comes back and into the pan. This keeps the bulk of the fluid temps in reason.

I used to pull a 10K trailer. Without being locked up the temps soared. I added the mystery switch. Put a pedal on the floor. Once I get rolling I tap the pedal. TC locks. Temps drop like a rock.

Running 500+ 1000+ at rear wheels now for years. Trans has probably 100,000 on it. Still flawless.
 
#18 ·
Traffic plays a lot with the temps.
I've been dragging around a 16' enclosed flat faced trailer all week.
Loaded to about 4500lbs 'hauling but' down the highway all is fine... under about 180.
Stop and go traffic while empty? Runs about 245.
 
#19 ·
Thank you to everyone who has offered some input on this. And I do apologize for being so slow to respond to anyone.. Been rather busy with moving, planning my fiancé and I's wedding, changing jobs ect.. I was going to be installing an oil cooler but had a set of ball joints fail on me so I blew the budget for that on carli bj's, track bar and new tires..

But I do plan to install one this next spring. I am not 100% sure how I would like to rout it yet but I think I will keep the factory water/oil heat exchanger and eliminate the one up front and add one under the bed or something.

My other thought to correcting this problem was to install a switch to manually engage the fan clutch exactly as described by steve05ram360.
 
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