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Discussion Starter · #1 ·
As a mechanic, Im very meticulous with my truck. I plug my truck in when the temperature drops below -15C, I use fuel additives and injector cleaner once a month, use premium gas, and full synthetic oils... and I watch my gauges like a hawk. (and bare with me here, im a Canadian and use a unique mix of standard and metric units here, it might get confusing...)

which leads to my issue. My truck is a 2010 ram 1500, 5.7 hemi auto 4X4 with 130,000 km on the odm, mostly highway miles, and I never take it off-roading. it was -35C this morning when I started my truck for the drive home from another shift at work. I let the truck idle for 30 minutes to let it warm up and defrost the windows. the road was icy and I was in 4 wheel driving at 100 kph (but I never shift between 2WD and 4H unless im under 60) and I noticed my trans temp was hovering around the 150-160F mark. This isn't in the red zone, but I know my truck, and it will maybe hit 145F on a hot summer day, and at -30 I knew my truck should be around 115-120. In fact when I drove my truck to work on Monday, my temp was at 125F with an outside temp of -18C.

I tried shifting to 2wd to see if it was my transfer case heating up, but no change. I pulled over and let it idle for about 20 minutes to see if there was any change, in both park and neutral, but nothing. I shut it down and looked under the tranny for leaks, clean. I checked the fluid with the engine running in neutral (hard to do considering at this time the temp was at 120F, between the cold and the hot check points) and the level seemed to be in the proper area, but I did notice that I did have a small patch of ATF on the frame rail under my trans cooler lines. not a lot, just enough to wet the lines and the frame rail, and I inspected to see if I could pinpoint the leak but could not see anything.

I wanna know what you guys think on this. I have a slight leak on the lines, but not serious and the oil isn't low. I don't feel the transmission slipping or shifting excessively, so what could cause my transmission temp to jump 30 degrees over its normal point, especially in such cold weather. possible internal trans issues? :thk:

Thanks for your input.
 

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Smells like trade in time..... But if u get. A chance check to see if u have oil in the transfer cases... There is a plug up top...u a mechanic so I don't have to get into it... Usually when it gets to normal operating temp I don't really think the temp will be cooler because its brick outside... Remember internally thinks are working like any other day... It might be slightly lower on cold cold days and slightly higher on hot summer days.. But over all if it shifts fine and doesn't make weird noise or smell u should e good to go.
 

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160F tranny temp is definitely not out of the ordinary. In fact that's where it should be sitting for optimal performance. My 1500 was always around 160-ish. But it does seem kind of weird that it all of the sudden jumped up like that especially with your weather so cold. I'm not totally sure how the tranny cooling system works on these trucks but I'm assuming there could be some sort of electronically controlled thermostat that's preventing the fluid from entering the tranny cooler to help it stay warmer :4-dontknow:

I would just keep an eye on your fluid levels and pay attention to how it's shifting and running. If it all seems normal I wouldn't worry about it.
 

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Discussion Starter · #4 ·
Thanks for the input guys, keep it coming.

Nemissis1: I've had the truck for 2 years and have watched my temps carefully and it varies a bit between hot and cold. On a 35C day it sits about 137-143f but in the cold it usually drops to around 118-125. I remember one day the temp was -52c with windchill and my tranny temp stayed locked on 114, coolant was 191 and oil only hit 177, that was a cold day... And I know it shouldn't bother me all that much since it drives fine and the temp is still way in the safe zone, but a 25 degree increase makes me wonder haha.

And Brandon, I thought the same thing about the thermostat, but I haven't ever seen it before, but then again, I work with big rigs, and on the old muscle cars, I'll ask around the dealership about it. As for my specific truck, mines always ran cool. I never saw it at 160 before.
 

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check if you have a cooler bypass. i had 2 trans go on different vehicles till they put them in, and they cut off the cooler in cold weather so the trans would be heating/cooling itself.
 

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Some of these trucks have a tstat/cooler bypass. It's at the inlet to the trans cooler/heat exchanger which is integral to the AC condensor.
 

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I doubt you have the cooler bypass,with the temps you normally run.
I have the cooler bypass on my 13,and it runs at 190 or higher on tranny temps in the summer
To check if you have the cooler bypass, look through the grill on the passenger side of the truck and see if there's an aluminium block that the tranny lines run into.
The bottom lines will be offset to accomodate the wax motor driver,and it should have the part number #55111005AC stamped into it
 

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I'm wondering if the fluid in your cooler was frozen, leading to no flow through the cooler. Trans fluid can get pretty thick at -35°C. That might be enough to restrict the flow.
 
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