Auto Trans operating Temps

SIKHILUXSURF

SIKHILUXSURF

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Hey guys just wantted to see what is the average temps your scangauge II's are reading during driving and what is the recommended temps? mine was around 158-175
 
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Keeping it under 200 is the idea. Over that, and the life of the fluid begins to shorten rapidly.

I regularly see 130 - 190, depending on how hot it is, and the type of driving I'm doing. I have an external cooler.
 
I have an external cooler bypassing the radiator.
Average Temperature is 198 - 204 deg.F on highway.
The maximum I've seen was 218 deg. F during stop and go traffic when outside temperature was above 90 deg.F
The dashboard ATF gauge is in the middle possition all the time.
Note that I use an aftermarket coolant.
 
On average, I see anything from 145-185.

I have spiked it up to 217 once. I was using the gas pedal to hold the truck on a hill rather than using the brake for about 10mins and 88deg temps outside.

I'm still rocking the stock radiator/cooler setup. However, I'm running Amsoil synthetic ATF.
 
wow nice guys! im running Redline D4 ATF and running A TRD trans Cooler in line with the oem rad trans cooler so i guess im in a good spot for trans temp then.
 
Scangauge II tells me 140-190. On a 5 hour drive on the highway, the temp sits right at 160 the whole time. If I drive highway, in town, all combined in one drive, it'll get up to 185-190, and only cool down to 170ish once it's that warm.

I'm using the B&M 70268 cooler only, no stock cooler.

I'm also running Valvoline MaxLife ATF.
 
alp said:
I have an external cooler bypassing the radiator.
Average Temperature is 198 - 204 deg.F on highway.
The maximum I've seen was 218 deg. F during stop and go traffic when outside temperature was above 90 deg.F
The dashboard ATF gauge is in the middle possition all the time.
Note that I use an aftermarket coolant.
Click to expand...

Sorry for confusing everyone. The above data is for the coolant temperature and NOT for ATF.
The ATF temperature is going back and forth between 150 and 190 in mix driving and is usually steady around 170 on a highway.
 
I have completely bypassed my stock cooler with a B&M 70268 cooler. In warmer temps, my ATF is around 160-180. However, I was towing a 3,800lb trailer 140 miles with a 3,500 foot elevation climb a few weeks ago, and the tranny got up to 233 for about 20 seconds as I crested Parley's Pass. I just about cried. The temps stayed right around 195 the rest of the way. I plan on draining and refilling the ATF a couple times now.

I'm a little concerned though that by bypassing the stock cooler, the fluid is staying too cool in the mornings now that the temps are down in the 50's. I drive in to work (90% highway) and the tranny only reaches about 120 by the time I get here. It's a 13 mile trip and takes me just under 15 minutes. What do you guys think? Is it worth it to route the fluid back through the stock cooler to warm it up? That sounds backwords, I know, but I'm just not sure how cool is too cool. If I drive it longer than 30 minutes, the temps climb to 145 in 50's temperatures, FYI.

Thoughts?
 
Last edited:
My external ATF cooler is also bypassing the radiator and I would like to know as well how cool is too cool. Anyone?
 
econhonda said:
What do you guys think? Is it worth it to route the fluid back through the stock cooler to warm it up? Thoughts?
Click to expand...

I don't think so. Remember that your radiator does not heat up until after the thermostat opens. By then the tranny should be warm enough any way. I really don't think there is very much difference in temps between the two arrangements. Certainly not enough to risk pink milkshake meltdown.
 
BTO said:
I don't think so. Remember that your radiator does not heat up until after the thermostat opens. By then the tranny should be warm enough any way. I really don't think there is very much difference in temps between the two arrangements. Certainly not enough to risk pink milkshake meltdown.
Click to expand...

Good to know. Thanks.
 
econhonda said:
I have completely bypassed my stock cooler with a B&M 70268 cooler. In warmer temps, my ATF is around 160-180. However, I was towing a 3,800lb trailer 140 miles with a 3,500 foot elevation climb a few weeks ago, and the tranny got up to 233 for about 20 seconds as I crested Parley's Pass. I just about cried. The temps stayed right around 195 the rest of the way. I plan on draining and refilling the ATF a couple times now.

I'm a little concerned though that by bypassing the stock cooler, the fluid is staying too cool in the mornings now that the temps are down in the 50's. I drive in to work (90% highway) and the tranny only reaches about 120 by the time I get here. It's a 13 mile trip and takes me just under 15 minutes. What do you guys think? Is it worth it to route the fluid back through the stock cooler to warm it up? That sounds backwords, I know, but I'm just not sure how cool is too cool. If I drive it longer than 30 minutes, the temps climb to 145 in 50's temperatures, FYI.

Thoughts?
Click to expand...


Remember that SGII temps are read at a pretty hot point...quite a bit hotter than the pan. The 233 you saw when towing was probably only 205-210 in the pan. Since it was for a short time, I wouldn't cry too much. :)

My setup is identical (no stock cooler, just 70268), and I've wondered about the "too cool" aspect too. I have my coolant temp showing on my SGII, right next to my ATF....and it's interesting to watch how they warm up. The coolant and ATF warm up very similarly until about 95 degrees. At that point, the coolant warms up MUCH faster. The coolant will be up to 160 and the ATF is still at like 105. When the coolant hits 190, the ATF can still be only 110-120 depending on the driving. As the fall comes on and temps drop I'm just going to pay close attention to it and make sure it's making it up to about 110 degrees in a reasonable amount of time. Anything over 110 is warm enough to not hurt the transmission.

alp said:
My external ATF cooler is also bypassing the radiator and I would like to know as well how cool is too cool. Anyone?
Click to expand...

Too cool is generally anything under 110. Obviously the transmission functions when the fluid is only 20 degrees.....the question is how long does it stay cold. It needs to be warmed up to that 110-120 minimum about as quickly as possible. Which is why the in-radiator style has merit. I might be replacing my radiator and running through both after a little more data gathering.

BTO said:
I don't think so. Remember that your radiator does not heat up until after the thermostat opens. By then the tranny should be warm enough any way. I really don't think there is very much difference in temps between the two arrangements. Certainly not enough to risk pink milkshake meltdown.
Click to expand...

You are correct that there isn't much difference once up to normal operating temp. The difference comes in how fast it gets there. Thermostat opens pretty quick in my experience, and tranny temps are still pretty cold when it does. From what I'm seeing in mine....not going through the radiator keeps it cold significantly longer. Definately not worth a Pink Milkshake, but if you replace the radiator, I'd go back through it.
 
So what's the problem with cool trans fluid? Has anyone experienced hard shifting or slipping or anything else suggesting that cool fluid is bad for the transmission?
 
quicksilvr said:
The coolant and ATF warm up very similarly until about 95 degrees. At that point, the coolant warms up MUCH faster. The coolant will be up to 160 and the ATF is still at like 105. When the coolant hits 190, the ATF can still be only 110-120 depending on the driving. As the fall comes on and temps drop I'm just going to pay close attention to it and make sure it's making it up to about 110 degrees in a reasonable amount of time. Anything over 110 is warm enough to not hurt the transmission.

Too cool is generally anything under 110. Obviously the transmission functions when the fluid is only 20 degrees.....the question is how long does it stay cold. It needs to be warmed up to that 110-120 minimum about as quickly as possible. Which is why the in-radiator style has merit.
Click to expand...

So basically you are concerned with the time the ATF is in the 95 to 110 degree range. Anything lower than 95 is beyond control of the radiator and anything over 110 is not harmful to the tranny. How much time does an average 4runner with a bypassed tranny cooler actually spend in that zone?

Also, where did you get your 110 degree cutoff? Can you cite anything on that?
 
Qyota said:
So what's the problem with cool trans fluid? Has anyone experienced hard shifting or slipping or anything else suggesting that cool fluid is bad for the transmission?
Click to expand...
None. We've had ours bypassed for 8 months now. Tranny has been flawless.
 
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