1988 240 coolant leak
 

I'm looking to buy a 1988 240gl for my 16 year old daughter. The owner is asking $300. It runs fine, but has several issues you'd expect from a 26 year old car with 280k+ miles. The main problem I am concerned about is a major coolant leak coming from behind the motor above the dip stick. I can fill the car with coolant, and have it completely empty and over heating in a few miles. Does anyone have any idea where the leak could be coming from?
Also, I've never owned a Volvo before. Are these good reliable cars? Is this a good deal or a money pit?