after driving,i shut car off and coolant back flushes into expansion tank.start-

i changed the radiator cap 1st thing but no effect

every time i drive before i start the car i must top off coolant in radiator.if i don't car will run hot for a minute then temp gauge goes back to norm range, however because of radiator coolant loss (when car is turned off) it back flushes into exp. tank ,but doesn't take coolant BACK to the radiator when engine is started again. when the car is shut off, it dumps into exp.tank overflowing the exp. tank. then if i go somewhere, i have to top off the radiator or engine will run hot because radiator is only partly full.if i drive with car like this i will also lose cabin heat.