I have a L Reg 180E and I noticed a overflow pipe??? coming out the water pump and going down the left hand side of the engine to the level of the sump (when looking at headlights) Why is water trickling out this pipe and what is it for???? Thankyou in advance

 

Until a more-experienced person provides better information: in general, the tube is to carry away the small amount of leakage of coolant from the water-pump seal; I understand "some" leakage is normal.
I will leave it to more experienced people to define "some", etc.

 

loose bearing, broken seal.

replace it now.

 

Whatever you do, DO NOT let it overheat, as you could blow the head gasket. Then you'll be into it for a lot more money than just a waterpump.