The survey at www.540i6.com provides statistics
about E39 radiator failures but I am interested
in hearing from others about

1) vehicle model. history (age, mileage) and condition

2) the circumstances immediately prior to the
  failure and a description of the failure event

3) actions taken upon becoming aware of the failure

4) information about where the radiator broke

5) consequences of the failure

6) who paid what for repairs

** ----------------------------------- **
My '00 540iA broke at 54k mi after 42 mo of service.

The break occured upon acceleration from a stop.  The
car had been parked for an hour previously and had just
been running for a few minutes.

Coolant first sprayed then exploded up through the gap
between the hood and fender at the leading edge of the
drivers side.  Vision was obscurred by coolant on the
windshield.  I immediately moved from the median lane
across to the shoulder and shut the car off.

An inverted L-shaped split occured on the side of the left
radiator tank at the forward edge just back from where
the horizontal reinforcement ribs on the front face wrap
around and end on the side of the tank.  The vertical leg
of the inverted "L" split was 3", the horizontal leg
extended back 1".

The car was moved to a dealer on a flat deck truck.
(In the absence of any apparent approved tie-down point
at the rear of the vehicle, the driver was permitted
to attach 'j-hooks' loosely to the lower rear control
arms to secure the vehicle in case of an emergency stop.)

The dealer replaced the radiator and inspected for signs
of combustion gas in the coolant.

BMWNA refused to honour the CPO warranty as the car is
currently outside of the US.  I paid $600 USD for the
vehicle transport, repair and cab fare.

** ----------------------------------- **

Regards,
  Ken R.