Is this a crazy idea to cool my 4L60E transmission?

[Geotrash]

From the GM chassis manual:



Also, if it's helpful specific to the 6L80:

In the February 2011 issue of Trailer Life magazine RV Clinic in response to a reader about the maximum transmission temperature allowed in a 2009 Chevy Silverado, the Tech Team had this response.

“General Motors’ in-house towing team expert provided RV Clinic with this statement: The maximum allowable automatic transmission fluid temperature is dictated by the transmission oil itself. The oil begins to degrade significantly above 270 degrees Fahrenheit, so we design vehicles so that in all but the most extreme conditions, the fluid temperature in the transmission sump stays below 270 degrees F.

We allow for up to 285 degrees F in extreme conditions (i.e. towing a trailer with combination loaded at GCWR in Death Valley). But for customer usage anywhere else in the country, even at GCWR, transmission sump temperature should stay well below 270 degrees F. Above this point, certain internal components, such as seals, begin to disintegrate rather quickly. Although newer synthetic fluids can withstand higher temperatures we still recommend this (270F) as a maximum temperature. "

 

[Geotrash]

I wasn't trying to be argumentative. You quoted the OP so I thought maybe you were responding to him. Didn't mean to offend you, truly. Just hoping the info I shared above is helpful.

 

[Marky Dissod]

I like that chart ... but as a pessimist who applies Murphy margin to everything ...

176°F / 80°C ..... 100,000 Miles ... Ideal Automatic Transmission Fluid Temp
194°F / 90°C ....... 50,000 Miles ... Max Recommended Sustained Temp
212°F / 100°C ..... 25,000 Miles ... MpG improves / Pressure Drops
If the powertrain is not working or playing hard, 212F / 100C is hot enough already.

230°F / 110°C ..... 12,500 Miles ... Varnishes Form
Not dumb enough yet?

257°F / 125°C ....... 6,250 Miles ... Seals Harden
Dumber?
275°F / 135°C ....... 3,125 Miles ... Clutches Slip
More dumber?
293°F / 145°C ....... 1,562 Miles ... Oil forms carbon, seals and clutches burn
Morer dumberer?

If the ATF temp sensor reads 230F, some of the ATF is even hotter than that.
That's why you should change the ATF every 40,000 miles -
because when the ATF temp sensor READS 176F, some of the ATF, somewhere, is 230F.

[EDIT]I change ALL the underhood fluids whenever ANY of them reach or exceed 230F.

 

[davidavidd]

The job is done!

Tomorrow night I'll go out and drive around a bit, although I won't be towing anything for now. Sorry if my question caused a bit of tension here.

PS: The thermostat was in terrible condition and I think it was the cause of the leaking radiator (increased pressure in the system + old radiator = cracks & leaks).
I also changed the TPMS sensors and both EVAP system solenoids (engine side and rear solenoid above the spare tire), no more check engine light

Stay tuned, I will publish the data when I have it. And to contribute to the discussion, I believe that anything above 230º is highly detrimental to any transmission, even for a short time.

 

[davidavidd]

Ook ok, mics on, the data arrived!
After driving for 5 hours on hilly roads and all the seats occupied, the maximum temperature reached was 179º F, min. 160º F.

It's not bad at all and it's much "cool" than what I achieved before, although I must also take into account that the other radiator was not in its best days.
Another conclusion I reached is that it is possible to cool the transmission below the engine temperature by passing through the radiator, it was false that the minimum temperature that was going to be obtained was the same as the engine coolant.

I hope to have similar numbers when towing because the weight I usually carry is not even 1200 pounds.

 

[Marky Dissod]

After driving for 5 hours on hilly roads and all the seats occupied, the maximum temperature reached was 179F, min. 160F ...
Another conclusion I reached is that it is possible to cool the transmission below the engine temperature by passing through the radiator.
It was false that the minimum temperature that was going to be obtained was the same as the engine coolant.

Your ATF never reached the engine coolant temp. For proof, get some real-time live readings.
You'll find that the engine coolant temp rises more quickly than the ATF temp -
there are no explosions / burning occurring inside the transmission.

However, mind that the ATF temp is not taken anywhere near the radiator, or the external cooler,
so you've no clue whether or not (any or some of) the ATF is cooling the engine coolant,
or if they are cooling each other.

GM would suggest that your MpG would improve if you allowed your ATF to get warmer.

 

[j91z28d1]

someday I've love to put a temp sensor in the passenger side of a ls radiator to compare Temps to the cylinder head coolent Temps.

I wouldn't be surprised if it's much cooler and water to fluid cooling will always be much more efficient than air to fluid.

im glad you did this.. be cool to hear how it does during a tow.