Maybe this is normal but I just happened to notice it this weekend doing some maintenance. My upper radiator hose was collapsed...I mean flat as it could be no longer round at the middle section. I could squeeze the hose somewhat back into shape and hear coolant being sucked into the pipe. Is this normal? While I'm thinking about odd things...I hear a "sigh" when I turn the engine off. I notice it more when I get home from work because I have the radio off and I'm in the garage with no other noises.