Join Date: Jun 2013
Location: Central Mississippi
You are just now finding this out?
It could be old and watery defunct coolant that is just full of rust. In that case the system needs to be flushed thoroughly and refilled with correct coolant. At best this shows that the PO neglected the vehicle.
It could be head gasket problems. Is there brown foam on the dipstick? In that case, let the fun begin.