hey everyone, i have a large coolant leak

its coming from the drivers side at the front of the car
the car never over heats, and the engine temperature remains central at all times

however, it is only when i fill coolant into the combustion chamber that it leaks.
after that, it leaks very minimal amounts or none at all

i have a 2L 95 mk3 golf.

please help. although it doesnt inhibit the cars performance, its just very annoying and looks quite tacky

thanks a heap