Ever since i took delivery of the 450 I have noticed a tiny pool of coolant under the engine after a decent run - after a quick diagnosis it was clear the water pump seals could not hold the pressure... several months and many many litres of top-up water later it could not be ignored any more and require urgent attention
The coolant flinging off the water pump pulley and spraying on the underside of the bonnet was clear enough evidence that catastrophic failure was imminent...