ok, just got this thing going and this happens... got a 67 with a 302 motor just put a brand new water pump in it last week. went for a cruise a few times then tonight decided to rev the engine a little in park...ok lot and all of a sudden coolant started flooding out behind the water pump. I havent taken it apart yet just thought id get some input as to what ur thoughts may be that it is...Im hoping just the new pump took a dump but not sure im going to b that lucky..

 

It's leaking behind the pump, against the block? Did you seal the gasket or just put the gasket in and bolt it up? Not trying to be rude, it just sounds like it might be leaking from the gasket being that new.

 

put a small amount of sealant around the gasket it was sealing just fine for a week or so just here and there test driving then gave her some gas and it just flooded out