Transmission Cooler

NoLegs · November 20, 2001

First off let me say I'm more of a manual transmission guy and automatics aren't really my cup of tea, but the truck I just got has a strong TH-350 in it and I don't see myself doing the old "swaparoo" to a manual.

Anyway, I know a transmission cooler is way better than running it through the radiator, but this truck is using both - the stock radiator cooler and an external cooler. I don't know why anyone would do this, because it is my thinking that you would be running your hot fluid from your tranny through a radiator that is already hot from your coolant of the engine.

Now I realiz the transmission runs hotter than the motor and the motor isn't actually going to increase the heat of the transmission fluid, but is it really necessary to use the radiator too? It seems that the most efficient way to cool would be to have the least amount of bends/connections in the line to begin with.

Also, the way it is setup is kind of "ghetto" anyway and I was going to cleanup the way it is ran, but like I said, should I clean it up with or without the raditor?

Any thoughts on this would be much appreciated.

November 20, 2001

This is just my opinion based on my experience. You'll find a lot of folks disagree with me, but hey, it worked for me.

I suggest running the fluid through an external cooler, then through the radiator cooler.

Your radiator should be running plenty cool to do the job except in extreme (towing, racing) conditions. In winter time (if you live in a cold climate), the external cooler could cool the tranny fluid down too much for proper shifting. The radiator will actually warm the fluid up to a decent temp that will make the tranny shift properly. If you only run an external cooler, I suggest mounting it behind the radiator to get some warming in cold weather.

I've used both of these configurations in Maine with good performance.

76BBSub · November 20, 2001

I agree 100% with Friz. The transmission will perform better if the fluid is at least a little bit warm. Your radiator will ensure that the fluid is around 160-210 depending on your thermostat. This will improve performance and may improve mileage as well. Just make sure the it goes through the radiator cooler last, which I believe you said it did.

Jeff

Shaners · November 23, 2001

When my friend lost his tranny 1 1/2 years ago in his early 90's Chevy truck, he completly plugged up the cooler in his radiator and his add-on cooler. The guy who rebuilt it for him put the largest aftermarket cooler on the truck and bypassed the radiator. This saved my friend from having to buy another radiator, and the person in the tranny shop felt good enough about it that he gave him a 2 year warranty. So far he's not had any complaints. (However I do agree on those cold winter days, his tranny would take forever to warm up).

textruckr · November 23, 2001

I guess that your location has a lot to do with your mounting location. Here in the sunny, warmer climes we all tend to route the trans fluid through the radiator cooler and then through the aftermarket cooler. Extended towing on a 95+ degree summer day will take it's toll on your transmission here in Texas. Of course the winters are not nearly as severe here as they are in Maine, but I still want the coolest fluid possible to keep the tranny happy. There is a trans cooler offer through Camping World that has a temperature sensing bypass - this may be the best of both worlds.

Check out this site for some good info on trans coolers:

http://www.dieselpage.com/haydento.htm

I like my fluid to stay around 150 degrees - it seems to be the best option when I use the Suburban or C1500 to tow. My C3500 has the NV4500 manual, so a cooler is not an option!

Low83 · April 13, 2003

My 700R4 has the fluid routed thru the radiator and then thru the external oil cooler mounted in front of the radiator for the best cooling possible, with triple digit summers and cold foggy winters the tranny hasn't missed a shift yet