2004 honda civic overheats
You might have a sticking thermostat. If it's sticking shut, it won't open when needed and the engine will overheat. Even though the water in the radiator is not hot then, the water in the block of the engine is boiling.
After that overflow, the cooling system was underfilled, so when the thermostat finally did open, it had plenty of room to refill, which is what you saw when the water got "suddenly sucked in".
My recommendation is to replace the thermostat (and gasket), because as a point of diagnosis, it is a relatively cheap part but can have terribly inconvenient consequences when malfunctioning. If you're handy, get a Haynes or Chilton manual from the auto parts store and do it yourself.
Also, the radiator cap is not good to mess with when the engine is hot. Doing as you did by opening it while overheated upsets the balance between the coolant in the block and radiator. There's a small rubber hose from the top corner of the radiator to a plastic (probably translucent) overflow tank on one side of your engine compartment. Under normal circumstances, you should check the coolant level there, as it exists to keep the system in balance. Note that I said "normal" - which means anytime it hasn't overheated to the point of leaking out of the radiator cap or leaking elsewhere.
Jun 10, 2009 |
2004 Honda Civic