E46Fanatics - View Single Post - [Cooling System Upgrade] 1-BAR Radiator Cap
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Old 10-06-2012, 10:36 PM   #104
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Join Date: Sep 2012
Location: Old Greg's Cavern
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My Ride: '13 128i, '04 330Ci
Originally Posted by SeanC View Post
The amount of water vapor in the expansion tank (hence the system) will not be more than 4% (even 100% humidity). It is negligible.

What is the total coolant fill up to the min level for a well bled system? If we knew this, we could calculate the expansion of the coolant using 3.8% expansion rule much more accurately.

Not saying your numbers are not reasonable, but biasing the results to initial values doesn't seem too justifiable to me. We should be able to express things as state functions, meaning depending on the properties of the system at a given instant.
Him assuming initial values is the best way to do this kind of thing. We're just trying for a sanity check of the system's pressure. If the volume of air in the ET changes by 30-50% when heated, then we know the system actually does operate at a fairly high pressure. That's all I really want to know. Then the cap is justified, but we still don't know why they made the system higher pressure.

Last edited by WDE46; 10-06-2012 at 10:36 PM.
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