This is really puzzling me. My heater core went and puked all coolant in my floorboard so I replaced it ( it never got hot when it went) I also replaced my thermostat. I can drive 20 miles or so and then all of the sudden it will start to move up on the temp guage then go back down if I turn the heater on, but the other day the heater didnt help. It went right up into the red and stayed there so I pulled over let it cool down added more coolant, checked my oil for coolant and drove it home without a single problem after that until I was pulling in my driveway 30 miles later the coolant light flickers[sm=dontgetit.gif] When this happens to me sometimes the resovior is full and trying to blow out steam from what seems like to much pressure and at the same time the radiator hose will have nothing in it, and vise versa. Can air in the system cause this and what is the best way to get rid of it if so. Any help is appreciated.

 

One of the most likely causes is air in the system, usually trapped by filling the system too quickly.

Sometimes it is possible to release the air by gently squeezing the hoses. If that fails it will be necessary to partially drain the system and refill slowly.

 

The new thermostat might be bad.