I have just fitted the correct radiator adjustment screw for the auto as the shorter manual one was in there and filled the radiator up with water and anti freeze. I have been running the car for 20 minutes but the needle is staying just at the top of the blue section on the gauge. The temperature in the car is luke warm. I have felt the hoses and the one going to the top of the rad is quite hot but the bottom hose is a lot cooler. this is strange because when i ran it the other day before fitting the correct screw it got to the half way mark on the gauge, 12 o'clock position. nothing else has been touched on the car, Any ideas??? the bottle is full and the top bleed screw lets out water when opened. i am stumped.