This is of course very unfortunate.
The truth in automotive manufacturing: shift a greater number of completely assembled and TESTED (that's where the problem is) to supplier. This approach saves money, especially labor required to assemble the vehicle. Instead of steering motor, rack, and steering wheel delivered separately by multiple suppliers, Tier 1 suppler delivers a fully assembled steering rack to the manufacturer.
Pierburg is a division within
https://www.rheinmetall-automotive.c...coolant-pumps/
The root cause lies in 2 separate parts:
- BMW relaying component specifications to Pierburg AND specific testing procedures
- Pierburg performing these tests for BMW
It's doubtful that extensive testing has been done to simulate a range of problems for this specific water pump. The risk of common problems is typically eliminated by good collaborative design techniques ... until these design techniques miss a few things. Component failure testing is expensive (because it often involves creating a test with multiple components working together), time consuming, and for a relatively inexpensive component it's rarely done.
To echo prior comment about Bentley problems, hot weather testing would easily reveal the problem of rear window falling out of the convertible top. Many car manufacturers do perform hot weather testing in Arizona. But - did the tests include "leave it in the Scottsdale parking lot for a few days" scenario?