Hear boiling water on the radiator - 2007 Nissan Sentra 2.0 SL Sedan

Flush cooling system maybe you need to Replace the Thermostat or radiator cap.

Of the water is boiling them it has run hot. There is no way around this fact. Get a compression test done first. This should reveal if any damage has been done. Then address the boiling off problem. This can be a air pocket in the line, incorrect anti freeze mixture, sticking thermostat, water pump, cap, etc.

Pam are you sure it's boiling? If the Antifreeze is boiling I'd think you'd see steam coming out of your reservoir as the water expands into the reservoir, but you didn't say you see anything like that.
Of course engines get hot, that's why we have the cooling systems but it doesn't sound like it's "boiling" to me with no signs of visible steam unless your antifreeze level is really low?

If it's really boiling, and you antifreeze level is good, then your reservoir should be getting filled up with expanded hot water that goes into it to catch it when it expands.

If the water isn't going into the reservoir, then maybe your antifreeze level in the radiator is too low and you need to add antifreeze?
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Best to fill the radiator with the engine cooled down. If you ever have to open the radiator when it's hot, NEVER open it with your bare hand as you could get scolded with boiling water. Instead use a big thick towel to remove the radiator cap off a hot engine. Again, if you can, just wait until the engine cools then open the radiator cap.

With the engine cool, you can fill the radiator with a 50/50 antifreeze mix. The 50/50 mix come premixed 50 percent water, and 50 percent antifreeze. So you can throw that stuff straight into the radiator.

Non mixed antifreeze needs to be mixed 50/50. Some people use 50 percent distilled water when they mix it because distilled water doesn't have the minerals in it that may get stuck in your radiator. That's being a bit picky about it though. Tap water works fine in a pinch. The other 50 percent is antifreeze. You can mix it right in the radiator too, put in a measured amount of the antifreeze, followed by the same measured amount of water. The water pump will mix it all together when you run the engine.

Put the cap back on and run the engine and if/when the water "boils" it should go into your reservoir. If it does boil in go in the reservoir then yes...your engine is getting hot and the antifreeze is boiling.

When the antifreeze boils, it's probably because your thermostat is stuck closed. That means the thermostat isn't letting water circulate through the radiator to get cooled. Thermostats are cheap...no more than $30 I'd say for most cars. Changing them is pretty easy too as they are usually right at the top of the engine. A mechanic may charge $100 to change it....but it's an easy job on most vehicles requiring just a couple sockets/socket wrench.

sounds like blown head gasket only fix is to replace it.

Check the over flow tank located in front of the passenger side glove box for water or fluid. When driving the car, listen by the glove box to see if you car hear a boiling sound. If you can hear water boiling or moving, check your heater core to make sure it is not plugged or bad. When the car starts to over heat, does the gauge register that it is getting hot? If it doesn't then check the thermostat to make sure it is not stuck open or closed. If its over heating and the gauge is not showing that the car is running hot before boiling over, then the thermostat is defective or not working. Try replacing it again.

Hi, If you see white smoke coming from tail pipe then you will know it is leaking through engine.
I would suggest after you replace head gasket, that you put new radiator fluid (50/50) mix and a new thermostat in. The fluid will keep it from boiling over. Good luck.

Check your radiator, any coolant left?

Do you have a coolant reservoir? Does the coolant level rise as the engine warms up and lowers as the engine cools off? If so, the engine cooling system is sealed. If the system isn't sealed, when it is cooling, it can't draw coolant from the reservoir. Does the radiator have a radiator cap, with cold engine, remove the cap, can you see coolant level in radiator?
How hot does engine get in degrees F? There is your thermostat and radiator cap. Water boils at 212 degrees f atmospheric pressure. With a 16 lb radiator cap, it should raise the boiling point about 32 degrees. The boiling point should be around 250 degrees F. w/o any pressure, I would suspect it would boil over in a hurry.

Sounds like a plugged radiator or bad water pump, assuming the thermostat was put in correctly. If you hear a loud whining noise from the water pump when running, that's probably the problem, and it's more common than bad radiators.

sounds like the thermostat may be sticking closed. i would check to see if the thermostat is opening or not