Hi There,if the water pump is actaully dribbling water out,then i would be very wary of buying the vehicle,sorry to sound so negative,but the harsh reality is that the current owner obvously doesnt give a damn about the vehicle,and the engine may have actually overheated which could end up giving you a big repair bill.If however its a gradual seeping leak you will be ok.Go back and check the rad header tank and see if there is any Coolant/Antifreeze in there,if not then the chances are the leak is bigger and all the coolant has been replaced with water.You should see the Green/Blue or Pink colouring of the coolant.The pump is fairly easy to do your self with reasonable knowledge,figure on $300.00 for a garage.I had a cherokee and it was a fantastic vehicle,extremely reliable,and a lovely drive.