2008 mk4 mondeo 1.8tdci

[G.I.T]

hi all i was wondering if i could get some help

today the mondeo over heated i opened bonnet to check water tank... when i opened it the when a brown water in it ..i thought oh crap head gasket but the oil was good no milky stuff on dip stick or oil cap.

i top up coolend drove for a mile there was no white smoke but the was no heat in cabin either but the messed up thing is the needle would creep up but if i slowed down the needle would come back down untill say i done 10miles which then the coolend bottle would be empty... would i be right in thinking water pump lost a fin and is leaking or EGR???? leaking??

is the water pump run by cam belt or aux belt

thanks in advens