Originally Posted by Fourn3833
Some radiators have coolers built in, but if the water is at 200 plus degrees than the tranny fluid is no cooler, hence the external coolers in front of the radiators.
Almost all vehicles with automatic transmissions have a separate heat exchange for the transmission built into the radiator. Even though the inlet water temperature going into the radiator is 200° (or whatever temperature thermostat is installed), what goes back into the engine is significantly cooler......that is what the radiator does for a living. The hot water goes into the radiator at the top, and goes back into the engine from the bottom of the radiator. Some transmission coolers are located at the bottom of the radiator, taking advantage of the cooler water ready to go back to the engine. Some may run down vertically on the none inlet side of the radiator, but the fluid will still come out of the bottom....the coolest part.
This is the 1st step in cooling down the transmission fluid, and for many vehicles that is enough. But in towing situations where the transmission fluid can really heat up, an auxiliary transmission cooler is needed to further cool the fluid, since the primary cooler my not be able to keep up.
Chap , DW Joy, and Fur Baby Sango
2006 Ford F150 Super Cab 4x4
2008 Surveyor 263