If you had an ET leak, that could be it. If still overheating, read up on bleeding more. Usually that'd be it.
Could be fan, I suppose, which lead to ET cracking, but ET could've cracked just from age and perhaps overfilling...which you want to be very careful not to do. Fill to between min and max. Maybe you should drive the car for a bit to monitor things closely?
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Mangofy your E46!