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Trans Temp too low?

L

Linebacker

New member
2005
Grand prix GTP-comp g

So last summer i installed a transmission cooler after getting temps around 212F after my rebuild. So after the cooler install the temps always sat around 180. Now that its winter and its starting to get cold i have noticed my transmission never quite gets there anymore. Today after about an hour of highway driving it never went over 118. If i am doing city driving it sits around 143, Is this hot enough for proper lubrication? And yes i have already tried putting cardboard infront of the cooler.

Problem i am worried about is if it cant break 118 on the highway when its 14 outside, how is it going to do when its -45 outside. (its gets very cold where i am now).
 


My thought was cardboard aswell. Is the cooler in a spot where it gets alot of air flow over it?

Perhaps place another piece of cardboard there aswell to limit even more air flow.
 
I installed an independent cooler just like you, and where I'm at it gets as low as about 15° at a minimum. Usually it's around the mid to high 20's in the winter. Although I dont have a temp gauge for the trans, I can tell its taking a really long time to warm up as well, so I'm in the same position. (i can tell because the torque converter wont lock until 70°, and it takes a while to get there sometimes) Except that your area gets a LOT colder. Definitely in your situation, and its a good idea in mine too, run the aftermarket cooler in series with the stock cooler. Before or after is the big debate, it's up to you though.

I also thought about blocking the air flow partially, never tried it yet though.
 
you guys keep forgetting the transmission adjust pressures and other thing based on transmission temp. transmission fluid will still move just the same when its cold or hot.

edit: didnt see your location
you might wana just want to go back to the stock rad cooler. but flip the lines so pressure is on top. and dont forget to flush it.
 
Why the "pressure" line on top? I thought the supply line was intentionally on the bottom so no air would ever get trapped in the cooler.
 
02NavyBlue said:
Why the "pressure" line on top? I thought the supply line was intentionally on the bottom so no air would ever get trapped in the cooler.
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I've never seen any of these myths in a transmission that's constantly filled with fluid, how the hell would air get into the lines, and if it did I'm sure you have bigger issues. I've ran my pressure line on top for years in all my cars I've owned without issue.
 


91parkave said:
I've never seen any of these myths in a transmission that's constantly filled with fluid, how the hell would air get into the lines, and if it did I'm sure you have bigger issues. I've ran my pressure line on top for years in all my cars I've owned without issue.
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So...whats the point of switching it from stock?
 
02NavyBlue said:
So...whats the point of switching it from stock?
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Pushing fluid from bottom to top requires more force than the opposite not as well as the cooler is simply a brick next to the radiator, no real Chanel's to flow through and not efficient as aftermarket's. Top to bottom would help.
 
Consider an LPD cooler. This is one that restricts flow through part of the cooler and allows the fluid to reach a temperature faster. It's a nice way to have the cooler w/o overcooling typically.
 
well its too cold for me to bypass the cooler at this point so if i am gonig to do it ill have to pay for a shop to do the bypass. I was just curious if someone had a actual temp number i could use as a reference as to what is hot enough.... even without the cooler i doubt it will get to operating temp in these conditions unless its a 2+ hour drive. So what temp should i be aiming for?
 


well i doubt i will be anywhere near that, Even if i bypass the cooler. Do you think running it at 120 is risking damage from being over cooled?
 
Doubt you'll damage it if youre just doing normal driving. Also consider when people are drag racing these cars the tranny temp isn't that high either for fsm operating temp
 
I have (2) Long LPD 18,000 GVW Double stack coolers on my GP that run outside of the radiator in the grille and have since 2008 on my 01 GP. The coolers have been on the car for 60,000 Miles now with total transmission mileage at 150,000 miles. The temperatures can get down to 0 where I live but normally are in the high teens/low 20's in the winter. I have experienced zero issues with the transmission with the coolers in the winter other than OD lockup takes about 3 miles of driving before the trans fluid hits 88 degrees, the OD engagement temperature. The temperatures you sited of 143 city driving and 118 highway are perfect and mimic mine very closely-135 city and 110-115 highway BUT not sure about -43 temps-that is really low. I use Dexron VI and have for years now and change the fluid and filter every 25-30,000 miles and the fluid looks great at every change and the pan is very clean-no sediment, particles-nothing.

Trans fluid lines using the radiator run into the bottom of the radiator and exit at the top on GM cars and have forever-thus the reason you want to slice into the top line after the fluid has been cooled by the radiator, if you choose to use the cooler in line with the radiator cooler.

The number 1 killer of any transmission is heat, by far! No getting around that issue. Lowering the trans fluid temp significantly will greatly extend the life of the transmission and the fluid life. Trans fluid temps that run consistently over 200 degrees can compromise your tranny. I have been using external trans coolers for 35 years now and have never had a tranny failure on any of my cars.

Hope that helps!
 
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Linebacker said:
well i doubt i will be anywhere near that, Even if i bypass the cooler. Do you think running it at 120 is risking damage from being over cooled?
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Well how long does it take to get to 120 is the question. You said 2 hours of freeway driving at 14° only got to 118, what will 2 hours of the same at -45 get to? It might stay below 70° for 20 minutes of driving.

And to jbamonte, Dexron VI is a part synthetic fluid too, maybe the OP should run that since synthetic fluids are known to perform better in extremely cold conditions. I run it in my engine anyway, even though we usually only get as low as 15°.
 


My tranny in 50-60 degree weather only gets up to 145 at highway. And at 30-50 degree temps it usually stays around 120-135.
 
DirtDog said:
My tranny in 50-60 degree weather only gets up to 145 at highway. And at 30-50 degree temps it usually stays around 120-135.
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But you've got a super-duper cooling cooler. Parallel flow design.

To the OP: just being curious, what cooler do you have on it?
 
cooler is a tru cool LPD cooler from TEP, transmission was rebuild last JAN and was filled with Dexron VI. It takes about 10-15 min to get to 143 in the city. How it will run in -45 im not sure, At what temp would i risk damage? what if it could not get over 68.. would that be a problem?
 
Well I can't say about damage, I think you'd be fine but you could never have any fun at those temps. I always wait til mine's warmed up before giving it any more than 1/4 throttle. Your gas mileage will be affected, as the torque converter will not lock until 70°

Yeah thats a pretty efficient cooler, it will really take heat out of the trans. I've got a little hayden 403 cooler what am I worried about lol.
 
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