Investigated this today. My car doesn't have the same setup as the linked thread. My previous e39 with m52tu engine was like it but my current car has an electric fan and doesn't have an auxiliary water pump like the thread.

Anyway, having googled it the only thing I can see that remotely resembles what google images throws up is part number 4 here. Could this be the faulty part. It is attached to the passenger suspension turret.
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