I just removed the upper & lower intake manifolds to replace the knock sensor. I completed that work, but know I have a problem putting coolant back in. I follow steps in the Haynes repair book to refill, but it always seems to push out coolant and overflow the overflow tank when heating up. I then shut the engine off, and both upper & lower radiator hoses and the bypass hose collapse. Coolant does not go back into the radiator from the overflow tank as it cools - it stays full. This happens with a U-shaped wire inserted under the radiator cap gasket as directed in the Haynes manual. I have taken off the upper intake twice before and never had this problem. It did not overheat or have coolant problems before this latest issue. Any thoughts on how to rectify?