This topic has gotten quite a bit of attention as the interest in bypassing the radiator ATF cooler has become a hot topic. This information is copied from the thread, http://www.thenewx.org/forum/showthread.php?t=30287 . I'm posting just this part of the thread for those who don't want to read the longer thread.
1. There was no evidence of the rad-atf cooler heating the atf. On three cold starts temperature out the cooler was always colder than temperature out of the trans as the engine and trans warmed up. As the trans warmed up the difference became larger. The difference is a few degrees when the temperature out of the trans is mid 90s and 13-14F when temperature is about 120F. It takes about 20 minutes for the temperature out of the trans to reach about 150F with normal highway driving when the air temp is about 75F.
2. The atf is heated in the return line to the transmission. From a cold start and during all operation the atf is absorbing heat. On one cold start at 75F ambient driving about 65mph, after 3 minutes temperature out of the trans was 108F, temperature out of the air-atf cooler was 99, and temperature into the trans was 104. At 10 minutes, Tout was 131F, Tair was 111, and Tin was 124. At 20 minutes, Tout was 147F, Tair was 121, and Tin was 137. I suspect some of the heat is from the steel outlet line. The two lines are clamped together. Without making a few additional measurements it is just a guess.
I am planning on making additional measurements in future. I have a trip planned to Ouray, CO, at the end of the month and will get some cooler ambient temperature data. I don't expect the rad-atf cooler to heat the atf under those conditions either.
Jeff
1. There was no evidence of the rad-atf cooler heating the atf. On three cold starts temperature out the cooler was always colder than temperature out of the trans as the engine and trans warmed up. As the trans warmed up the difference became larger. The difference is a few degrees when the temperature out of the trans is mid 90s and 13-14F when temperature is about 120F. It takes about 20 minutes for the temperature out of the trans to reach about 150F with normal highway driving when the air temp is about 75F.
2. The atf is heated in the return line to the transmission. From a cold start and during all operation the atf is absorbing heat. On one cold start at 75F ambient driving about 65mph, after 3 minutes temperature out of the trans was 108F, temperature out of the air-atf cooler was 99, and temperature into the trans was 104. At 10 minutes, Tout was 131F, Tair was 111, and Tin was 124. At 20 minutes, Tout was 147F, Tair was 121, and Tin was 137. I suspect some of the heat is from the steel outlet line. The two lines are clamped together. Without making a few additional measurements it is just a guess.
I am planning on making additional measurements in future. I have a trip planned to Ouray, CO, at the end of the month and will get some cooler ambient temperature data. I don't expect the rad-atf cooler to heat the atf under those conditions either.
Jeff
