So, I'm sure I'm over-thinking this, but found it interesting. Using the diagram below which shows the auto transmission cooling setup... Note that the coolant which is routed to the auto transmission heat exchanger includes the the heated coolant from the engine along with the coolant exiting the heater. That means the transmission fluid has to be hotter than the mixture coming from the engine in order to cool the transmission. So, with hot coolant cooling the transmission fluid, I wonder why BMW continued to use a fan/clutch on automatics?
Last edited by Sansho; 12-08-2010 at 08:15 PM.