The BMW radiator and coolant hoses are part of the cooling system of your vehicle that feed the cooling channels inside the block of your engine. This is the system that transfers the heat created by the explosion in the combustion chamber to the surrounding air outside of the vehicle. The radiator hoses and components of your coolant system must be unobstructed so the flow of coolant can be maintained at a regular rate. To help this to occur, the coolant should be changed annually for many BMW models. Periodic inspections of your radiator and coolant hoses should occur regularly to ensure your engine is in proper working condition. If a leak does occur, there will be a spot or puddle under your vehicle. Today's coolant used in a BMW is either green or red and not clear as water is. If this is noticed, then locating the leak is a priority. An overheating engine cannot perform properly and the possibility of seals and gaskets developing leaks and fail on other systems of your BMW. There can also be a leak in a coolant hose that is very minute. These can be noticed by looking for a sediment deposit on them that is of a different color that the component. Generally it is white or green. Any time a BMW radiator and hose is replaced, the entire cooling system, should be drained and refilled with fresh coolant. This will help to prevent any amount of contamination from being in your engines cooling system. It is also advisable to inspect the radiator and coolant hose for the development of cracks and splits before they begin to leak so you do not experience a failure while you are on the road.