When the first batch of radiators began to fail, engineers would surely have looked at the reason why this had occurred, either poor build quality or badly designed rads, if it was engineering fail the only long term fix would be to redesign the rad, BMW would have provided all the relevant tech specs regarding cooling. As it effects bother Plus Four and Plus Six it looks more likely to be poor quality material, they would have been pressure tested and past the test, so I believe the fix is a new header which is only part filed this would probably allow for expansion of the coolant, leading me to think increased pressure in the rads caused the rads to split. The cost to MCC to replace all these rads under warranty is huge and the total cost for both fixes will probably result in future model releases put on hold. What I don't get is why the cars that have had replacement rads have to go back to the factory?
