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      08-18-2011, 06:17 PM   #11
First Lieutenant

Drives: 2006 330i E90
Join Date: Aug 2011
Location: So Cal

iTrader: (0)

Without knowing their design, it is hard to predict the junction temperature. My guess is that there might be a feedback loop in the design, whereby the flow rate of the coolant is increased (up to some maximum, of course) if the ambient temperature increases. 70C is a generally accepted "case temperature" of an electronic circuit board that processes power. In the water pump case, the circuit is likely to be a DC to AC converter (DC from battery and AC to drive the motor and to control its speed).

Last edited by queensfield; 08-18-2011 at 06:18 PM. Reason: typed too fast