[Got_Torque_570]

I got thinking (never a good thing) about this during my trip to a street rod show. I know these truck have a trans. cooler up behind the grill/bumper. But I was wandering if there was a fan that kicked on when the trans. oil hits a certian temperature, or does it always cool the same, not matter if it's 115 or -10. Does anyone know how the trans cooler work?? Or am I making this more complex than it really is.

 

[ozhoo]

Good questions Torque. Once the trans fluid leaves the tranny it enters the radiator (referred to as an in-tank cooler) then it enters the oil-to-air cooler before it's returned to the trans. The cooling fan is controlled by the PCM based on engine oil and cooling temps, but not trans temp.

Now the trans temp is monitored by the PCM to control the cold/hot shift strategy and to control torque converter lockup. How cool is that /ubbthreads/images/graemlins/cool.gif

O

 

[AutoJim]

[ QUOTE ]
Good questions Torque. Once the trans fluid leaves the tranny it enters the radiator (referred to as an in-tank cooler) then it enters the oil-to-air cooler before it's returned to the trans. The cooling fan is controlled by the PCM based on engine oil and cooling temps, but not trans temp.

[/ QUOTE ]

You were doing great right up until the last sentence. /ubbthreads/images/graemlins/smile.gif

The Visctronic fan drive does have trans fluid temp as an input, not engine oil temp. It reacts to coolant temp, intake manifold temp (CAC performance), AC demand, and auto trans fluid temp. There are some additional logic trees in place for idle/city traffic fan speed management, but those are the four main inputs.

 

[Got_Torque_570]

Thanks for the replys. I figured that there had to be some fan/computer control for cooling the Trans. oil. I am still amazed at how many things computer control and monitor on these trucks.

 

[Charlie_in_TX]

It was also my understanding the torqueshift had a thermostat. Yes/No?

 

[AutoJim]

[ QUOTE ]
It was also my understanding the torqueshift had a thermostat. Yes/No?

[/ QUOTE ]

There's a pressure-activated cooler circuit bypass, but as far as I know, no "thermostat" per se. The bypass will open if the cooler circuit has a backpressure greater than X (some number I don't know offhand), which is indicitive of the ATF sorta almost gelling in the cooler circuit.

Watch this -- a little birdie will soon tell me if I got this right or not. If I post a correction, you'll know. /ubbthreads/images/graemlins/smile.gif

 

[AutoJim]

[ QUOTE ]
[ QUOTE ]
It was also my understanding the torqueshift had a thermostat. Yes/No?

[/ QUOTE ]

There's a pressure-activated cooler circuit bypass, but as far as I know, no "thermostat" per se. The bypass will open if the cooler circuit has a backpressure greater than X (some number I don't know offhand), which is indicitive of the ATF sorta almost gelling in the cooler circuit.

Watch this -- a little birdie will soon tell me if I got this right or not. If I post a correction, you'll know. /ubbthreads/images/graemlins/smile.gif

[/ QUOTE ]

Right on cue... /ubbthreads/images/graemlins/smile.gif

My knowledge base has been expanded. Why yes, the TorqueShift does have a thermostat on the cooler circuit, unlike the 4R100 which has the pressure-activated bypass described above.

 

[RockPSD]

How does the oil/water cooler work on this trans? It seams like one everything gets up to temp it would actually heat up the trans fluid. Doesnt the trans run at a much lower temp than the water flowing through the radiator?

 

[Casey_1]

The trans cooler in the radiator is on the "cool" side of the radiator. That's after the water has been cooled by passing through the radiator. The water there is 30°-100°F cooler than the water leaving the engine, so it is almost always cooler than the transmission.

 

[RockPSD]

Thanks!
I knew it was in the bottom (cool) side of radiator. Just wasnt sure how much cooler it was there.

 

[04crew]

dont worry about thermostats on a trans cooler. the cooler the trans is, the better. you cant overcool automatic transmissions. they love the cold. if you are really working your truck, get the biggest cooler that you cant fit. your transmission will thank you.