That's the logical answer but what I can't figure out is....since I lost a great deal of fluid by taking the waterpump off, fluid that was inside the block, when and how would the thermostat open if there is no fluid in the block? The other thing is this, I just ran the thing for fifteen minutes in a heated garage (yes I have the shopvac hose on the tailpipe going out the door) and it got to normal operating temp but not over. The top radiator hose is under allot of pressure. I'm starting to wonder if I have the thermostat in backwards. Which way does the business end of that thing go anyway? Toward the front or back? I always thought the big end went toward the block.