The steam was coming out of the overflow tank. When I was driving home, I am reasonably certain that radiator cap was completely shot. It has a new one now, and I have yet to see any actual steam coming out with it. And its a 0.9bar cap. So when I get it to the shop Monday I'll pressure test, then if it passes, I'll put in the new water pump. If it fails, I'll talk to the guy with the Camry.I don't think so.
In a closed water system (assume you did not have any antifreeze in it), if your cylinder walls got so hot as to boil water at the contact surface between the water and the outside cylinder walls, that steam would condense back to a liquid as soon as it got to an area in the closed water (coolant) system below the boiling point temperature. Water will boil at 212 deg F at sea level. In your car, you likely have a 0.9 bar radiator cap (or about 13 psig), and the boiling point of water increases about 3 deg F for every 1 psig it is above atmospheric pressure. So at 13 psig, add another 40 deg to the boiling point, or about 252 deg F. Certainly somewhere in your cooling system, even assuming you have no coolant flow, the coolant will be less that 252 deg F in a 13 psig pressurized system, and that steam will condense back into liquid water (i.e.; it is unlikely for the coolant to boil away).
But, the original owner said there likely is a block problem. The bubbles you saw likely were was not boiling hot water steaming away, but rather combustion gases getting into the cooling system. Your coolant could very well be going the opposite direction (into your combusion chambers) and leaving via the exhaust.
If you cooling system is still all together, before I would change your water pump, I would do a pressure hold check on your cooling system. Do it cold and again after the engine has reached normal operating temperature. If the cooling system does not maintain a set pressure, there is a leak in the cooling system, and it could very well be coming from a cracked block or a cracked head.
You should also check your coolant that still remains for exhaust gas. There are test strips available for making this test. If this test comes up positive, you know you have an exhaust leak into the cooling system, which is sufficient evidence of a major problem.
I would do at least the exhaust gas test of the coolant (of course, you need enough coolant to do the test, and you need to have run the engine long enough to create the potential for the exhaust gas to appear in the coolant), likely the coolant pressure check, all before messing with putting a new water pump on the engine. Best to know this first.
Good luck with your analysis & repairs.
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