Overcooled transmission?

[JimPghPA]

Originally Posted By: dlundblad
Assuming the fluid only flows when the car is in drive, perhaps drive it how I suggested and pull over somewhere and check the temperature ASAP? Immediately put it into park to keep it from cooling down.

You shouldn't have any moisture in your transmission whatsoever. Water is a byproduct of combustion.


Changes in atmospheric pressure from the normal changes in the atmosphere, and from the vehicle going up and down hills causes some air to move in and out of the air space in the trany. That air has some moisture in it, and some of that moisture condenses out as water, that is absorbed into the trany fluid. If the trany fluid ability to hold the moisture in suspension is exceeded some of that water will be present as water not in suspension with the trany fluid. That water can cause parts to rust.

 

[Avery4]

What should I do?

 

[MolaKule]

My feeling is if the average ATF SUMP temp is kept below 110C or 230F, your ATF should not show accelerated oxidation.

I would say any temp between 32F and 230F is ok.

If you measured with an IR thermometer at the outside of the pan, you can bet your fluid temp is at least 20F higher. So 160F to 190F is a good range.

 

[Avery4]

Thanks for the help.

 

[ARB1977]

Originally Posted By: Avery4
I checked it by using an infrared thermometer on the bottom of the trans.

I'll bet your temps are warmer than that.

 

[Avery4]

I can easily touch the dipstick after driving 1 hour in stop and go or highway driving and it feels like hot bathwater. Is that bad?

 

[HangFire]

Originally Posted By: Avery4
I can easily touch the dipstick after driving 1 hour in stop and go or highway driving and it feels like hot bathwater. Is that bad?


That's probably more reliable than the infrared thermometer.

Let me ask you this, are you still running the fluid through the bottom of the radiator? If so, is that before or after your add-on transmission cooler? It should go through the radiator after, so it can pick up some heat as the engine warms up.

 

[Avery4]

I am running the fluid from trans to radiator to external cooler and back. Is that correct?

 

[MolaKule]

Originally Posted By: ARB1977
Originally Posted By: Avery4
I checked it by using an infrared thermometer on the bottom of the trans.

I'll bet your temps are warmer than that.


Quote:
If you measured with an IR thermometer at the outside of the pan, you can bet your fluid temp is at least 20F higher. So 160F to 190F is a good range.



This info is from a comparison of IR pan temps with an OBDII scanner.

 

[Yah-Tah-Hey]

At one time, a thermostatic valve for AT oil coolers was available to keep the fluid at operating temperature.

 

[HangFire]

Originally Posted By: Avery4
I am running the fluid from trans to radiator to external cooler and back. Is that correct?


That's not correct. It should be trans to cooler to radiator and back. On cool days, this will warm up the transmission fluid to an optimal temp. (It will also cool on hot days while towing, even 200F is "cool" compared to fluids coming in that are even hotter).

 

[EdwardC]

As long as it's coming up to temp enough for the torque converter to lock up, I would say that it's getting hot enough.

 

[Kiwi_ME]

Better to install a temp gauge on the hot line and see if your temps were actually getting too high before fitting the cooler.

 

[HangFire]

Originally Posted By: Avery4
I installed a Hayden High Performance 512 transmission cooler on my 2005 Civic automatic.

Originally Posted By: Kiwi_ME
Better to install a temp gauge on the hot line and see if your temps were actually getting too high before fitting the cooler.


Seems to me it's already fitted.

Properly configured, the combination of a cooler and the radiator brings transmission fluid up to temp quickly and keeps it from going over temp. It also increases the volume of fluid, which reduces concentrations of wear components and sheared lubricant, and creates a larger thermal mass, making overheating more difficult.

 

[il_signore97]

Just for another point of reference, I have an old Chev Venture van that I use for housework year-round and towing in the summer. I have a decent size stacked plate tranny cooler installed with about half of it in direct airflow through the grille, and the other half with indirect airflow from bumper air inlets.

In the summer, when towing, the temp normally sits between 70-90 C depending on how fast I'm driving or if I'm climbing hills. I have never seen it above 90 C in the few times I've hooked up to the OBD II and pulled transmission temp.

In the cold winters we have here, coupled with much shorter trips and no towing, I'm certain that the fluid hardly ever warms up. I don't have any OBD II data, but I can tell you that it warms up enough to allow for torque converter lock up after about 5-10 minutes of city driving (few minutes less for highway). So it still warms up "enough".

This van had the cooler installed at 120,000 km (along with Amsoil ATF). It is now many many years later and has over 300,000 km on it. The original transmission still shifts and drives like new for the most part. The Amsoil ATF and filter have been changed once since the cooler was installed.

I doubt any harm will come from your temps.

 

[CBR.worm]

Some cars (Toyota's used to) use coolant temp to trigger lock up, or in some cases allow the use of overdrive. It used to be ~140f coolant temp that would allow O/D and/or lockup.

 

[rslifkin]

The cooler on the Jeep has no t-stat either, and even in sub-zero weather, it takes no more than 1 - 2 miles to get the trans warm enough to feel normal and enable OD and lockup (fluid temp of 50* F). I've thought about finding a fairly low temp (160*) thermostat to add in there though, as the trans does feel a little nicer when the fluid is a bit warmer.