I've found that unless I lube the o-rings w/a water soluble lubricant (pure antifreeze works, so do other *lubes*...) that things don't go well regardless of what water pump I'm working on (E46M3 or E53 X5 [N62]).

However, check the weep hole first as it can happen that it is defective, especially if a reman'd part.

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Kirk
Las Vegas
2016 X5 40e Mineral White/Black Dakota Leather, ZLL, ZCW, ZDA, ZDB, ZPP, multi contour seats, rear side window shades, HK stereo
2011 E90M3, 6-speed manual