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      07-07-2009, 11:49 PM   #14
That's what she said...
bigjae1976's Avatar

Drives: 11 E90 M3 Individual
Join Date: Mar 2006
Location: Milwaukee, WI

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Garage List
2004 BMW M3  [4.50]
2011 BMW E90 M3  [5.00]
2013 BMW 328i  [5.00]
Originally Posted by jml View Post
I'm not convinced it is boiling since there is no indication that there is cavitation in the pump. Unlike the E46, the E90 has a PS oil cooler. It's probably a slight expansion in volume due to temp, and an increase in pressure due to sustained high RPM and high temp.
I thought the issue was that the pump is right next to the headers. So extended track use heats up the headers which increases the p/s pump temp with also increases the p/s fluid temp.

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