Quote:
Originally Posted by skymangs
Actually an AT cooler runs your transmission cooler if it is outside of your radiator. I have found that the transmission actually runs warmer with an integrated cooler.
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make sure you get the right kind of external trans cooler, a plate cooler works much better than a fin type.
you are right that an external cooler runs cooler than a radiator mounted cooler but there are two reasons the rad cooler is a good idea:
1. the trans takes longer to warm up with an external cooler, and a cold trans is a sluggish trans. the engine warms up much faster and works as a trans fluid heater in warmup and freezing weather.
2. surface heat transfer works much better in fluid than air (yes air is a fluid, but a relatively weak one), the fluid allows conduction of trans fluid heat to the coolant through the body of the cooler, increasing the efficiency of the transfer. plate and fin external coolers rely on CONVECTION, convection is pretty inefficient which is why you need such a LARGE radiator or external trans cooler compared to the little tiny trans cooler mounted in the radiator.
transmission damage is exponential over about 300 degrees, and your radiator cooling system can do a lot of heat transfer before it gets to even 260. a lot of guys with heavy duty trans applications will ADD a plate style trans cooler to the existing rad cooler to keep the warmup/cold weather performance and even help shed heat. my neighbor followed this advice on his tow rig and his trans temp never gets over about 200.