LS3/4L65E Cooling

[Bee-otch]

I read that I should let the radiator cool the engine and use a separate cooler, (remote?) for the trans. Does this sound like a good plan or are there other options I should look at? Any help would be greatly appreciated. Thanks

[JimLev]

If I do decide to add a tranny cooler (I'm using the 4L65e too) I'm going to plumb it in series with the cooler in the radiator.
The car is pretty light so the tranny shouldn't be developing a lot of heat unless you are tracking the car on very hot days.

[AZREALTOR]

I've done both. With me it is more about engine cooling than the transmission. If I have limited cooling capacity for the engine I will keep the trans off the radiator and cool it with a stand alone cooler. I have a 56 Chevy pickup I I built in the 90's and ran separate cooling systems with a 350/350 combo. A couple years ago I changed it to an LT1 with a 4L60 and continued with the stand alone cooler while upgrading the engine radiator to a modern aluminum aftermarket unit. With this combo the engine ran right on the thermostat temp but the trans ran hot. Ultimately I connected the trans to the cooler, then through the radiator and back to the trans. Having done this it now maintains a nice even temp in both the engine and trans even in the Arizona summer.

[NAZ]

Depends. If you're running a stock stall speed lockup converter you won't be generating a lot of heat to begin with so running through the integral trans cooler in the radiator will likely work just fine for your application. If you live in PHX and never drive anywhere were it gets cold a stand alone trans cooler would also work if properly sized. However, if you live in an area that has cold winters then you want to run the trans oil through the radiator even if you run a separate trans cooler and you want the oil to be returned to the trans from the radiator so you have consistent temps regardless of the ambient temperature.

I'm in the process of swapping to a Powerglide with a 4500 RPM stall speed converter and that will require a large heat exchanger to keep the trans happy. I'm installing a plate style that will support a 30,000 lb tow rig as a stand alone cooler. My configuration would very likely overtax the radiator so stand alone is the best option and my car will never be street driven in cold weather.

[AZREALTOR]

Not to drag this out but what NAZ said in his first paragraph is exactly how I am running mine and for the very reasons he describes. I set mine up this way after talking to the tech guys at Hughes performance trailer during the Arizona Nationals. He explained that the newer electronic transmissions have many dissimilar metals in their components and need to run at a constant temperature to perform properly and have any life expectancy. FWIW

[Bee-otch]

Thanks for the reply’s. The LS3/4L65E is the 430hp connect and cruise package from Chevy Performance. I’ll be using the car as a weekend cruiser in SW Florida, not as hot as AZ but the humidity makes it feel feel that way in the summer... Occationally we have some cool mornings in the winter, looks like I’ll run the trans cooler through the radiator to keep the temp consistent. My big concern are the engine/trans temps in the summer, I’ll keep an eye on the gauges and add a cooler if necessary. Thanks again for all your help!