[jasrking]

I am confused about external coolers....do they need to be run through the radiator or do the lines just run to the external cooler and back to the tranny?

[sunsetdart]

You can go either way, thru the external and thru the radiator, but most just go thru the external cooler and the trans. That way you are cooling only the trans and not adding any additional heat from the radiator.

[cr55]

Been using an external cooler on a streetrod for 18 years, no problem. It just goes thru the cooler, not the radiator.....CR

[Frisco]

Originally Posted by jasrking

I am confused about external coolers....do they need to be run through the radiator or do the lines just run to the external cooler and back to the tranny?

Automatic transmissions work best when the operating temps are around 180 degrees.

For most installations of an external cooler; I would suggest that the line runs to the cooler and then thru the radiators built in cooler/heater and then back to the trans. This will enable the trans fluid to reach and maintain the correct operating temps while at the same time providing additional cooling needed when towing or running a high stall (more slippage and thus more heat) torque converter.

Another method that can be utilized and not run the line thru the radiator is a thermostatically controlled valve in the line that connects the external cooler and the trans. This will open and close as needed to maintain the correct operating temps.

Having the trans fluid too cold can be as bad as having it get too hot.

[curtis73]

Originally Posted by Frisco

Automatic transmissions work best when the operating temps are around 180 degrees.

Having the trans fluid too cold can be as bad as having it get too hot.

I agree completely, but if you're wondering about it getting hot enough, take a morning drive around the block and then lay your hand on the TC. Just that 1/2 mile jaunt will get things quite warm in there, so getting it up to temp doesn't seem to be an issue.

I run a large, 4-pass, 1/2" tube cooler with a dedicated 10" electric fan that gets triggered by an adjustable thermostat on my tow rig. I have it kick on when the tranny temps hit around 220. It doesn't go through the radiator. It only comes on every once in a while when not towing, but it will cycle on and off when I have 10k behind it. That tells me its getting up to temp during daily driving, but its still adequately cooling at max effort.