Just when my car was running excellent something goes wrong...Sound familiar. I pulled the wrong sensor and it broke so I replaced it. The coolant sensor on the rail on top near the fuel lines. So air must have got in the lines and for the life of me it wont flow now because of air in the system. I jacked it up. The lower hose is just warm. I put the shop vac on the rad cap. Still wont go. Water pump is new. I just shut it down. Gauge gets three quarters up is that ok for now. I think for now Im going to take it out for small rides and play with it a little, It might just catch and go away.