From what I have come to understand, cavitation due to low coolant level/overheated coolant is the primary issue in pump impeller failures.

https://blog.craneengineering.net/wh...ump-cavitation

https://en.wikipedia.org/wiki/Cavitation

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'03 X5 4.4 Sport, last of the M62s (8-03 build date)
I believe in deadication to craftmanship in a world of mediocrity!