View Poll Results: Is my transmission running too cold?
|
Yes, get a thermostat!
|
|
1 |
50.00% |
No, leave it alone!
|
|
1 |
50.00% |
07-16-2019, 01:39 AM
|
#1 (permalink)
|
Master EcoModder
Join Date: Jul 2017
Location: Memphis, Tn
Posts: 463
Thanks: 320
Thanked 107 Times in 81 Posts
|
Transmission running too cold?
Hello everyone, I have a somewhat unusual question. If you haven't figured out by the title, I am concerned that my 2005 Honda Civic's transmission might be running too cold. I installed a Hayden 679 transmission oil cooler (the biggest one I could find, rated at 30,000 pounds) when I installed my Mishimoto racing radiator 5 years ago. The transmission oil cooler seems to work very well, and I am concerned that my transmission may not be warming up enough.
I don't have a trans temp gauge (although I will probably install one eventually) and my trans has no temp sensor, so I rigged a thermometer as a test. I used a small hose clamp to attach my Klein multimeter's thermometer to the oil cooling pipe coming out of the transmission going to the cooler (the hot one) and I set up the multimeter inside the car to monitor trans temp while I drive.
I am actually surprised at how cool the transmission runs with my setup. Today was a cool day for Memphis (only about 80 degrees). The highest temperature I saw was around 135 degrees, and that was while I was pushing it up a pretty steep hill with the converter unlocked. The temp was around 115 degrees most of the time while cruising down the highway with the converter unlocked, and if I unlocked the converter the trans ran at around 120 to 125 degrees on the highway.
So I am wondering if this is too cold, or if this is a good temp to run at. I am pretty sure it is harmless to the transmission since my old trans lasted to 243K miles with good maintenance and this cooler, but I imagine MPG may suffer slightly from running so cold all the time, especially in the winter.
I can get various thermostats to control the trans temp. Most seem to open at around 180 degrees, although some are higher or lower. However, I would rather not install a thermostat unless I need to because I don't want to add another point of failure. If the thermostat were to stick closed and I didn't know it, the trans could quickly be destroyed.
So what do you think about my low trans fluid temperature? Is it harmful to the transmission, and how much would you expect for this to affect gas mileage? Thank you very much in advance!
|
|
|
Today
|
|
|
Other popular topics in this forum...
|
|
|
07-16-2019, 02:00 AM
|
#2 (permalink)
|
Master EcoModder
Join Date: Aug 2018
Location: USA
Posts: 455
Thanks: 180
Thanked 101 Times in 77 Posts
|
Is the pipe metal or rubber? Rubber is a good insulator, which would give you a false low.
I would expect the temperature to be closer to what the engine operating temperature is, because the engine is heating up the coolant.
135 sounds kind of low. I'm not sure what the norm is though; the AW4 transmission that my Jeep has is known for running hot.
Edit: I misread what you said. I did not know it is an oil cooler. 135 seems low still.
|
|
|
The Following User Says Thank You to Taylor95 For This Useful Post:
|
|
07-16-2019, 08:32 AM
|
#3 (permalink)
|
Master EcoModder
Join Date: May 2009
Location: Australia
Posts: 1,510
Thanks: 325
Thanked 452 Times in 319 Posts
|
Why would a hypermiler need a trans cooler that's bigger than stock? Even those of us in the hottest climates struggle for temp.
|
|
|
07-16-2019, 12:04 PM
|
#4 (permalink)
|
Master EcoModder
Join Date: Sep 2012
Location: Victoria, BC
Posts: 1,747
Thanks: 75
Thanked 577 Times in 426 Posts
|
good reason to stick with the cooler line running through the radiator...well, assuming the radiator is ever up to temp, which it never is...
Ok, good reason to run the oil cooling lines through the hot side of the cooling system.
|
|
|
07-16-2019, 12:23 PM
|
#5 (permalink)
|
Master EcoModder
Join Date: Jul 2017
Location: Memphis, Tn
Posts: 463
Thanks: 320
Thanked 107 Times in 81 Posts
|
Quote:
Originally Posted by Taylor95
Is the pipe metal or rubber? Rubber is a good insulator, which would give you a false low.
I would expect the temperature to be closer to what the engine operating temperature is, because the engine is heating up the coolant.
135 sounds kind of low. I'm not sure what the norm is though; the AW4 transmission that my Jeep has is known for running hot.
Edit: I misread what you said. I did not know it is an oil cooler. 135 seems low still.
|
Great info, thank you. I clamped the thermometer to the metal part of the pipe, so I think I should be getting a fairly accurate reading.
|
|
|
07-16-2019, 12:32 PM
|
#6 (permalink)
|
Master EcoModder
Join Date: Jul 2017
Location: Memphis, Tn
Posts: 463
Thanks: 320
Thanked 107 Times in 81 Posts
|
Quote:
Originally Posted by oldtamiyaphile
Why would a hypermiler need a trans cooler that's bigger than stock? Even those of us in the hottest climates struggle for temp.
|
My main focus wasn't gas mileage, it was performance and longevity. The racing radiator that I installed had no built in trans oil cooler. I used to live in Asheville, so climbing long, steep mountains in hot weather was a daily occurrence, I didn't go easy on it while climbing, I added probably 30-40 HP over what this car had stock, I used to occasionally pull a "small" trailer (although sometimes I overloaded it pretty bad, the trailer was about 2500 pounds when I moved to Memphis. Oops.) And sometimes I push it hard, like flooring it from a stop.
|
|
|
07-16-2019, 12:37 PM
|
#7 (permalink)
|
Master EcoModder
Join Date: Jul 2017
Location: Memphis, Tn
Posts: 463
Thanks: 320
Thanked 107 Times in 81 Posts
|
Quote:
Originally Posted by Stubby79
good reason to stick with the cooler line running through the radiator...well, assuming the radiator is ever up to temp, which it never is...
Ok, good reason to run the oil cooling lines through the hot side of the cooling system.
|
My racing radiator has no trans oil cooler. And even if it did I don't know how much heat it would actually add to the fluid being on the cold side of the rad. Probably not much, it may even cool the fluid in the winter when the thermostat isn't open much or at all.
|
|
|
07-16-2019, 02:55 PM
|
#8 (permalink)
|
Master EcoModder
Join Date: Dec 2010
Location: USA
Posts: 1,171
Thanks: 352
Thanked 268 Times in 215 Posts
|
I would say yes just because you want the oil to thin out to spec. If its too cool, it is just causing extra friction and a slight loss in mpg.
I assume this car is an automatic?
__________________
"I feel like the bad decisions come into play when you trade too much of your time for money paying for things you can't really afford."
|
|
|
The Following User Says Thank You to hayden55 For This Useful Post:
|
|
07-16-2019, 06:17 PM
|
#9 (permalink)
|
Master EcoModder
Join Date: Jul 2017
Location: Memphis, Tn
Posts: 463
Thanks: 320
Thanked 107 Times in 81 Posts
|
Quote:
Originally Posted by hayden55
I would say yes just because you want the oil to thin out to spec. If its too cool, it is just causing extra friction and a slight loss in mpg.
I assume this car is an automatic?
|
Thank you for your help. Yes, it's an auto. How many MPG do you suspect I may be giving up by running the trans this cold? I would guess no more than 1 MPG, but I'm not sure
|
|
|
07-16-2019, 08:08 PM
|
#10 (permalink)
|
Master EcoModder
Join Date: May 2012
Location: Tampa, FL
Posts: 1,745
Thanks: 206
Thanked 420 Times in 302 Posts
|
For what it's worth, GM trucks let you see trans temp from the cluster, the '12 2500 at work (6.0 iron block and 6speed) runs around 160-170°F. Our Yukon hybrid (6.0 aluminum block, very similar to LS2, with 2ML70 4 speed) also runs about 160-170°F.
__________________
Last edited by ksa8907; 07-20-2019 at 02:14 PM..
|
|
|
The Following User Says Thank You to ksa8907 For This Useful Post:
|
|
|