I am not going to debate if the water pumps have plastic impellers or not. If you read roundel or bimmer, there are times of articles referencing the plastic impeller failures. Maybe the x5 is metal. BMW has repeatedly replaced parts which used to never and replaced th with partsade of materials which do. Ask anyone who wanted to replace the bogus lifetime trans fluid on a 5 series. The trans pan is plastic which cannot be reused because it is plastic. The list can go on forever

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2012 X5 50i ZAP(2VA, 336, 465), ZTP, ZPP, ZPS(6VC), ZCW, ZRC, 322, 4UB, 4NC, 610
2011 ///M3 Silverstone II
2011 X5 50i(lemon)
-- SOLD --
08 550 Msport
07 X5 4.8I sport
04 545i sport
02 4.4i sport
01 540I M/sport
00 SL500
97 SL500