QuestionI had a rapid boil over in a 2001 Elantra. The coolant violently boiled out of the overflow tank. I dont thik it is the thermnostat, because I was getting heat in the car, and while trying to check the problem, the top radiator hose is hot, and the bottom is cool, as it should be.. Is the engine air bound? if so, is there a way to bleed the system?
AnswerIf one hose is hot and the other is cold, you don't have any coolant flow. As the fan runs, you should feel hot air coming off the radiator, but this shouldn't be enough to make the coolant warm or cool to the touch. Remember that normal operating temperature is about 185 degrees F.
You should start with replacing the thermostat. You should also remove the radiator cap and check the filler neck and top of radiator. I've seen these cars overheat badly enough to melt the radiator, damaging the filler neck and blocking the cooling tubes. After you add the new coolant, start the engine and allow it to reach operating temperature. You should see the coolant flow, and the fan should blow hot air when it comes on. Let the fan cycle twice. This should bleed the system of air. Top off as necessary (should be just a little more coolant).
Most importantly, don't operate the vehicle until this is repaired. If you overheat the car too badly, it will damage the cylinder head.
