I have a 93 Sunbird, Cobra / Ford 5.0L. She's been running hotter than usual, and I have changed the thermostat and impeller, but they checked fine. As I began to back flush the system, I noticed a missing screw (see pic) and water jetting out from the hole. I'm guessing if water is coming out during back flush, that in normal operation water will pump out here as well, instead of going toward the engine. Is this a possibility? Thanks!