I have a 85' Chevy Silverado with a Rebuilt 305 engine and have problems... I needed a new radiator so i bought one... Then the problems started.... From there my water pump blew, lower radiator hose blew, thermostat housing blew, numerous thermostats stuck wide open, had the front freeze plug leak, and then yesterday the back two began leaking... i've replaced everything and as i was driving my truck tonight the freeze plug right below the left water jacket of the water pump just popped out... i just replaced that freeze plug not even two weeks ago... what could be causing this?