m104 water leak
 

My M104 has been leaking coolant for sometime and I have traced down where it is from.Standing in front of the car there is a U shaped hose 1/2 to 3/4 of the way down the block on the right hand side just under the exhaust manifold.Its about 100mm in length and app. 15mm in diameter.Part number 104 203 0382.
Does anyone know the function of this hose and easiest way to replace it?
thanx