Originally Posted by trader4

Explain to us how it can not be a manufacturing defect. The cooling
system has a cap with a pressure relief. ALL the components of that
system should be able to withstand the max pressure allowed by the
relief valve and there should be significant margin beyond that. All
the engineering principles say that. If the tank leaked because of
excessive pressure, then either it was defective and it failed at
normal pressure, the pressure relief in the cap is defective, or BMW
engineers are idiots.