Hi there i hope i've not got serious trouble brewing,over the last twelve mouths or so i'm having to top my coolant up every two months or so whereas before i never had to touch it,the coolant looks ok the same green colour as always and i always use volvo antifreeze,i have not noticed any leaks anywhere and the car runs the same with no steam coming out the back,so where's it going,i am having my cam belt changed soon and i might as well change the water pump just to be on the safe side,any ideas,just hope its not the cylinder head gasket,ged ps from inside the car there is no sign of water on the carpet or the car misting up so i don't think its the matrix