My car had been running fine for a long time. I've noticed that its been spewing some coolant around the radiator lately. I can let the car idle and itll be fine. When I drive it like 1 mile the add coolant buzzer sounds. The temperature gauge goes up and what not. When i pull back into the yard you can hear the car bubbling.I let it idle while putting coolant in it before i went on the drive. What do you think is wrong with my car.

 

I just had this problem with my 86 rx7. I flushed the radiator, changed thermostat out, changed the rad cap out, and added new upper and lower hoses. I also cleaned the resivoir out. When I put the antifreeze back in I poured it in very slow so air doesnt get trapped in the system. After I filled the rad. up I burped the rad(squeeze the upper and lower hoses causing air to bubble out.) After Be sure to check the rad. once the car cools off and continue to burp the rad.

 

Well for us 86 guys. It is really hard to get all the air out of the system. Especially in at the top of the radiator where the coolant level sensor is located. Mazda fixed it by adding another cap at the top of the radiator to get the air out.

I take the sensor off the top of the radiator and fill it till all the air is out. Then I put the sensor back on and fill it up the rest of the way. Be careful not to over tighten the sensor, its plastic and will break easily. This is from expereince. For the slow leak, if it is in the radiator I would just dump some of that leak stop stuff in. I had a slow leak that I could not find and my fluid keeped getting low. So I dumped some in and has not lost any fluid since. But get some quality leak stop if you take that path.