[ParadeinBerlin]

I cracked open a water pump that was $120 new on eBay. This pump has a plastic top housing reminiscent of the Continental, VDO, Gates water-pumps. The reason why it failed was coolant contamination to the board which fried a terminal, cheap plaster/putty was the only guard against the high pressure of hot coolant and the electrical board. When your BMW electric water pump fails, the first symptom while driving is the electric radiator fan cycles at 100%. This is very audible, and shortly after you will see a "engine overheating" with a yellow thermometer symbol on the dash-cluster. If you ignore the message, the next warning will show the same thermometer symbol in red with the prompt "engine is overheated" on CIC iDrive. The power is quickly reduced to 3,000 RPM, basically BMW limp mode. If you're still ignorant enough to continue to drive, you will damage the cooling system and the engine block/ components themselves. This china-pump lasted around 24,000* miles according to the shop manager, the N54 that had this pump installed is completely seized. One thing I noticed is all the torx bolts are different torque specs, the gaskets are brittle and they come apart with some pressure from my fingernail.

[bleicht]

Any evidence of the source of the failure?

[ParadeinBerlin]

Originally Posted by bleicht

Any evidence of the source of the failure?

From what I observed, there was brownish corrosion around the metal pins for the connector harness and some corrosion on the terminals closest to the rotor on the third picture attached to the right. There isn't a sure way of knowing since the vehicle sat in the mechanic lot for almost 14 days before it was taken apart and scanned for codes. The plastic impeller was still intact, it didn't disintegrate.